COMBUSTION APPARATUS FOR AN UNDERWATER THERMAL … · 2018-12-06 · The combustion system consists...

..Jil ' ....

0 GROUP 4

Downgraded ot 3-year intervals ; _ · declassiHed after 12 years.

NAVWEPS R EPORT 8998 U N O TS 3969

n--------~-t:~ COP Y

lllllllllllllllll llll llllll llll llll llllllllllllllllllllllll lllll

E 0

t.t 6

: I I I I

'

· ( 3 1788 00074 2570

COMBUSTION APPARATUS FOR AN UNDERWATER

THERMAL PROPULSION SYSTEM (U)

by

C. A. Reisman J. M . Caraher D . N. Jackley

3 Underwater Ordnance Department

ABSTRACT. A combustion apparatus that p ro vides a variable flow rate of 2500° F gas to the boiler of a closed - cycle steam power plant was designed and developed for use in an underwater thermal propulsion system. The propellants are h i gh - pressure gaseous oxygen and liquid hyd r o carbon fuel i n stoichiometric ratiq with recir culated diluent water to control the gas tem perature . The combustion system consists of an i gniter chamber , a main combustion chamber , and a flow-control device which maintains fue l, oxidizer , and diluent - water ratios over the op erati ng range from full power to l / 25 full p ower. A variable - area nozzle maintai ns any desi r ed combustion-chamber pressure between l 00 and 3 , 000 psi over the entire flow - rate range . The apparatus is capable of multiple restarts and should yield operating periods of at least 100 hours without maintenance . (UNCLASSI

'1 U.s ·. NAVAL ORDNANCE

China Lake, California

0

U.S. NAVAL ORDNANCE TEST STATION

AN ACTIVITY OF THE BUREAU OF NAVAL WEAPONS

J. I. HARDY, CAPT., USN WM. B. MclEAN, PH.D. Commander Technical Director

FOREWORD

A variable-flow combustion apparatus for use in the closed-cycle thermal power plant of the Moray research vehicle was developed at the U. S. Naval Ordnance Test Station, Pasadena Annex , under Bureau of Naval Weapons Task Assignment No. R TU- 2D- 000/216-1 /S447. Hardware development started in early 19 61 and continued until early 19 64.

This report is similar to that given at the American Institute of A e ronautics and Astronautics second annual meeting in San Francisco, 26- 29 July 1965 (AIAA Paper No. 65-481), but contains additional specifications.

Only a brief d e scription of the comple te power plant and Moray vehicle is given here. Further information may be obtained from the Moray Data Book, 1 March 19 61.

This report represents the considered opinions of the Propulsion Division.

R eleased by J. W. HOYT, Head, Propulsion Div ision 14 January 1966

Under authority of D. J. WILCOX, Head, Underwater Ordnance

Department

NOTS T echnical Publication 3969 NAVWEPS R eport 8998

THIS DOCUMENT CONTAINS INFORMATION AFFECTING THE NATIONAL DEFENSE OF THE UNITED STATES WITHIN THE MEANING OF THE ESPIONAGE LAWS, TITLE 18. U.S.C. , SECTIONS

.793 AND 794. THE TRANSMISSION OR THE REVELATION OF ITS CONTENTS IN ANY 'MANNER TO AN UNAUTHORIZED PERSON IS PROHIBITED BY LAW.

REPRODUCTION OF THIS DOCUMENT IN ANY FORM BY OTHER THAN NAVAL ACTIVITIES IS NOT AUTHORIZED EXCEPT BY SPECIAL APPROVAL OF THIS STATION.

ED

•

·•

Standard Display

Title: ( U) COMBUSTION APPARATUS FOR AN UNDERWATER THERMAL PROPULSION SYSTEM.

Accession Number: AD0369228

Personal Author(s): Reisman ,C A ; Caraher ,J M ; Jackley,D N

Corporate Author: NAVAL ORDNANCE TEST STATION CHINA LAKE CALIF

Corporate Source Code: 251100

Report Date: Feb 1966

Abstract: ( U ) A combustion apparatus that

Distribution/Classification

Distribution Code: 02- U.S. GOVT. AND THEIR CONTRACTORS

Distribution Statement: Distribution: No Foreign without approval of Chief, Bureau of Naval Weapons, Washington, D. C. 20360/or Naval Ordnance Test Station, China Lake, Calif. 93555.

Citation Classification: Unclassified Report Classification: Unclassified Collection: Technical Reports

Page 1 of 1

provides a variable flow rate of 2500 F gas to the boiler of a closed-cycle steam power plant was designed and developed for use in an underwater thermal propulsion system. The propellants are high-pressure gaseous oxygen and liquid hydrocarbon fuel in stoichiometric ratio with recirculated diluent water to control the gas temperature . The combustion system consists of an igniter chamber, a main combustion chamber, and a flow-control device which maintains fuel , oxidizer, and diluent-water ratios over the operating range from full power to 1/25 full power. A variable-area nozzle maintains any desired combustion-chamber pressure between 100 and 3,000 psi over the entire flow-rate range. The apparatus is capable of multiple restarts and should yield operating periods of at least 100 hrs. without maintenance. (Author)

Descriptive Note: Technical publication,

Annotation: Combustion apparatus for underwater thermal propulsion system.

Pages: 72 Page(s)

Document Location: OTIC

Report Number: NOTS-TP-3969 ( NOTSTP3969) , · NAVWEPS - 8998 ( NA VWEPS)

Task Number: RTU-20-000/216 1/S447 ( RTU200002161S447)

Monitor Acronym: NAVWEPS

Monitor Series: 8998

Descriptors: ( U ) *FUEL SYSTEMS , *COMBUSTION CHAMBERS , UNDERWATER PROPULSION , FUELS , OXIDIZERS , PROPELLANTS , COMBUSTION , LIQUIDS , GASES , INJECTORS , CONFIGURATIONS , REGENERATIVE COOLING , VARIABLE AREA NOZZLES , EXHAUST NOZZLES , FUEL INJECTORS , HEAT EXCHANGERS, SYSTEMS ENGINEERING , PERFORMANCE(ENGINEERING) , SPARK IGNITION , JET ENGINE FUELS , OXYGEN , HYDROCARBONS , WATER

Identifiers: ( U) JP-4 FUEL, RESTARTABLE ROCKET ENGINES

Fields and Groups: 131001 -Submarine Engineering

Change Authority: C TO U GP-4

Citation Status: Active

NA VWEPS REPORT 8998

CONTEN TS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l

C ombustion-Chamber Ini t i a l Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Igniter Development .. ... .. . . ............. . .. ....... .......... l 0

Elec tri c Ignition .... ........ . ...... _. . . . . . . . . . . . . . . . . . . . . . . . . . . l 6

Main C hamber With Conical Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . l 7

T es ting of Mai n Chamber With Conical Inj ection .. . .. ..... ....... 25 T es t Objectives ... ... ..... .... ....... ... .. ... .. .. ....... . .. 28 I gniter Improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Main Combustion Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

M e t er ing ........... ...... .. ... ... ..... . .... ..... .. .......... 30

H eat Exchanger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Variabl e -Area Nozzle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Facility and Instrumentation .......... .. . ... ................ ... 42 R ecorded and Displayed Information . . .. ....... .............. 46 Calibrations .............................................. 46

C onc lusions and R ec omme ndations ..................... ....... . . 47

App e ndixe s: A. H eat Transfer Analys i s of Moray Combus tion- T e st H e at .

Exchanger . . .. . .. .. . ....... .... ........ ......... ... • . ... 49 B. Gas Temperatur e Analysis for Single- Tube H eat E x change r

for Moray Combustion T ests . . . .... . .. .. . .......... . . _. ... 65 C . Adiabatic Flame T e1npe ratur es for JP-4 - Gas eous Oxyg~n -

Diluent Water at 68 Atmospheres ..... .. .............. : .... 69

111

... .

NAVWEPS REPORT 8998

iv

NEGATIVE NUMBERS OF ILLUSTRATIONS

Fig. 1, LHL-P 24079; Fig. 2, LHL-P 23291; Fig. 3, LHL-p 27044-3; Fig. 4, LHL-P 27186-2; Fig. 5, LHL-P 30600; Fig. 6, LHL-P 30725, 30724; Fig. 7, LHL-P 30729; Fig. 8 , LHL-P 30607; Fig. 9 , LHL-P 30608; Fig. 10, LHL-P 30609, 30 711; Fig. 11, LHL-P 23841; Fig. 1 2, LHL- P 30694, 3069 5; Fig. 13, LHL-P 30609, 30717; Fig. 14, LHL-P 24074; Fig. 15, LHL-P 30807-2, 30810 -1; Fig. 16, LHL-P 30807-1; Fig. 17, LHL-P 30918-4, 30918 -1; Fig.18, LHL-P 30809 -3, 30809-2, 30809-1; Fig. 19, LHL-P 30810-2; Fig. 20, none; Fig. 21, LHLp 30821-3, 30821-4; Fig. 22, LHL-P 30867-1, 30867-2; Fig. 23, LHL-P 27186-3; Fig . 24, LHL-P 30918-5, 30918-2; Fig. 25, LHL-P 27244; Fig . 26, LHL-P 27186; Fig. 27, LHL-P 27042-1, 27042- 2; Fig. 28, LHL-P 30548; Fig. 29, LHL-P 30841-3, 30841 - 2; Fig. 30, LHL- P 2 7042-3, 2 7042-4; Fig. 31 , LHL-p 27044-1; Fi g . 32, LHL -P 30822-1, 30822-2, 30841-1, 24582; Fig. 33, LHL-P 30816-2, 30816-1; Fig. 34 , LHL-P 27044-2; Fig. 35, LHL-P 27186-1; Fig. 36 - 43, none.

All illustrations unclassifi ed.

u

•

•

UtN6bASSIFIE·D NA VWEPS REPORT 8998

u

INTRODUCTION

A combustion system that provides a variable flow of hot gas to a closed-cycle steam power plant for a small, manned underwater vehicle was designed and developed at the U. S. Naval Ordnance Test Station (NOTS), Pasadena Annex.

As shown in Fig . 1, the 1400- shaft horsepower propulsion unit features a combustion chamber that will burn either diesel oil or JP-4 fuel and gaseous oxygen w ith added diluent water (for a maximum of 6300 horsepower of chemical reaction energy) over a wide range of

FIG. 1. Proposed Powerplant Section of Experimental Moray Vehicle.

propellant and diluent flow rates. The chamber is cooled regeneratively by recirculated diluent water . A multiple restart feature is provided by a separate chamber in which a small bleed flow of fuel and oxidizer is ignited b y a spark plug to provide a pilot li ght. Vehicle buoyancy requir ements made the use of high-pressure gaseou s oxygen as the oxidizer a lo gical choic e . V e hicle trim requirements are met by ballasting the oxygen stor age tanks w ith sea wa t er , which also increas e s o xygen utilization by acting as a displacement agent. The arrangement or propulsion elements is shown schematically in Fig. 2.

The objectives of this development program we re as follows:

1. To establish des i gn parameters for a combustion chamber capable of high combustion efficiency over a wide range of flow rates.

1

N

(::,;

400°F/

EXHAUST CONDENSATE SEPARATOR

REGULATOR~ GASEOUS OXYGEN

TANK

...._....__.....__,: COMBUSTION j CHAMBER ;

i ~O~~oF-~~

., .

PUMPS

FEED WATER

DILUENT WATER

ELECTRIC MOTOR

PROPELLER

AUXILcY'IO-----w~::;(------------- r~} -POWER BATTERIES COOLING SURFACE CONDENSER

150°F 12 PSIA

FIG . 2. Powerp lant Layout Schematic.

•

z ~ < ~ M 1:J Ul

?;j

M 1:J 0 ?;j

r-3 00 -..() -..()

00

c::

•

•

•

UNGlrA&SIFIED NA VWEPS REPORT 8998

2. To develop a propellant flow- contro l method a nd combustionchamber des i gn that w ill allow a 25: l var i ation in power output w ithout wasting exce ss heat.

3 . To determine the effects on combustion of direct combustion chamber discharge into the boiler, thereby necessitating a l a r ge characteristic chamber l ength.

4. To i nves ti gate methods of contro lling gaseous oxygen flow rates und e r var iable pressur e and dens i ty conditions .

5. To create and perfect a method of controlling combustion- system pressure and adapt the resulting device for automa tic control.

6. To deve l op handling techniques for high-pressure ( 6, 000 to 8, 000 psi) oxygen.

7 . To develop a reliable and simple method of i gnition a nd r es tart . 8. To demonstrate durabi lity and reliability of the combustion

apparat us for sustained operation.

S eve ral propellant- i njector designs we r e cons id e red. One was a fixed- geometry inj ector i n whi ch flow rates are controll ed by ext e rna l v alves, one each fo r oxi dizer, fuel, and dilue nt water . Its success depends on the injection pressures, a nd consequently the inj ec tion velocities , being high enough to g i ve effici e nt m ix ing at the lowe st fl ow rate. A var i ation of this des i gn uses spring-loaded pintle s in the inj ector to decrease the size of the i njector areas at reduced flow rates and thus make the i njection pressures more n early linear .

A second configurati on was similar to an inje ctor developed at the Naval Air Ro cket T e st Station (NAR TS), Do ve r, N. J . , for a va riable thrust rocke t motor (R ef. l ). It f eatur es an annular piston moving back and forth to cover and unco ver rows of ( l) fuel-injection holes 1n a central tub e and (2) oxi dizer-injecti on holes in the c h amb er w all. The nec ess ity of contro lling three flows instead of two, the proper placement of the p ilot li ght, and the sealing of sli ding surfaces at .high temperatur es and across inj ecto r holes pr esented additio nal design compli cations .

A third design approach was to use var i able-injection areas to enab l e the i njector to accomplish me t er i ng w ithout ext ernal valves. Such a design is similar i n principle to the N OTS va riable-thrust rocket (R e f. 2). Many of the same compli cations were encounte r e d . A disadvantage ar i s es because sensitive control i s r e quired at rates of only l / 30th maximum flow, while proper ratios still must be maintained.

D evelopment work was d i vided into six maJor area s:

l. Main combustion chamber 2. I gniter 3. M e t er ing or throttling 4 . Boiler simulation or heat exchanger 5. Variable-area exhaust nozzle 6. Instrumentation

If 3

NA VWEPS REPORT 8998 UNCLASS15~D~L COMBUSTION -CHAMBER I N ITIAL DESIGN

Figure 3 shows how the NAR TS variable - thrust rocket motor design was adapted to the requirements of this pro g ram. Considerable experience had been gained at NAR TS using this type of injector with propellants that were essentially nonhyper go lic because 9 O% of the hydrogen p eroxide was inj ected as a liquid, w hile only l O% was decom p ose d to i gnite the atomized mixture of fuel and peroxide . One of the desirable f eatures of this des i gn is the di gital nature of the control action, w hich maintains the mixture ratio to close tolerances as the sliding piston cove rs and uncovers separate sets of orifices . Figur e 4 shows the variation in injection pr essur e to be expected as the piston uncovers new ports.

Five sets of inj ec tor holes are used. With a different s i ze and numbe r of holes in each set, the chamber is designed to vary the combustion e n e r gy level over a range of 25 : l in five d i scr e te steps. D e p e nding upon the exact reduced-load efficienci es , this low e rs the shaft speed from full to approximate l y l / 15th full speed. Since the prototype positive -displacement fuel pump will pro v ide a continuously variable flow rate , only the inj ector pressur e drop will experi ence a ste p varia tion as each injector hole set is brought into o p e ration. The chamber is designed so that this pressure drop remains w ithin the limits es timated as n ecessary for adequate inj ec tion ve lociti es. The p'ressure drop discontinuiti e s at five diff e r ent flow rates (five different p i ston positions) co rr espond to abrupt changes in flow area as the inj ec tor hole sets are suddenly covered and uncovered.

A similar s ituation occurs at the gas eo us oxygen inj ec tor hole s, except that this flow w ill b e controlled by pressure regulators rathe r than by a pump. As the discrete injector hole sets are uncovered, the re gulator w ill abruptly change the supply pr e ssure to maintain a smoothly variab l e flow rate. Thus a curve similar to the one shown in Fig. 4 would exist for the gaseous oxygen inj ector , except that flo w rate would now be the dependent variable.

The flow rate of diluent water w ill be cont rolled by a pos i tivedisplacement pump similar to the fue l pump. However, since the wa t e r - inj ec tion orifices w ill not be covered and uncovered by the pis ton movement, the wate r-inj ecto r 6P w ill vary in a single continuous curve with flow rate. Spring - loaded pintles are plac ed in each wat e rinj ector orifice so that flow area w ill va r y w ith flow r ate in order t o m inim i ze the 6P change between extr eme flow conditions.

The conditions described a b ove for ope r a tion w ith pumps and r egu lators we r e s i mulat ed in the t est pit of the N OTS Propulsion Laboratory at Mo rris D am b y using metering va l ves in the flow lines .

One modification to the basic NAR TS des i gn r e quired for this application was the provision f or d iluent - water inj ec tion. As shown in Fig. 3 , this is accomplished in such a way as to provide not only cooling for the annular control piston, but a lso to separate and

4 U CLASSI~

•

•

u-:

-$-1 '

Section A -A

Diluent - wa ter pa ssa ge (3)

AI

Fuel-oil

inlet

Section B- B

Cox

injectors

Diluent- water

injectors (4)

•

Fue l-oil metering rod

Oil inlet

FIG . 3. Original Combustion Chamber With Like - on- Like Fuel-Oil Injection in Central Tube.

Heat -

z ~ < ~ M "d Cll

!;0 M "d 0 !;0 f-3 00 '-.()

'-.()

00

0"

c:

,_, 0 ..., u ~

'2 -f I

g; "' 8 u

<C

·~

"' 0.

0. <1

•

280 ~----~-------,------~------~----~r-------r-----~~-------r------~------ll----~r-~

Piston position

No. 1--+h ~--- No . 3 ---~---- No. 4 ,...,. No. _c::

240 Maximum design

200

160

120

80

40

0 ~------L-----~-------L------~------L-------L------L------~------~-------L----~L-~ 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0 .1 8 0.20 0.22

JP-4 Fuel Flow Rate From Pump, lb/sec

FIG. 4. Pressure Drop A cross JP-4 !P..jector Versus JP-4 Fuel Flow Rate •

•

z ~ < ~ M 1:1 Cfl

~ M 1:1 0 ~ f-j

00 --o --o 00

c:

..

•

•

•


dilute any leakage of fuel and oxidizer past the after end of the piston.

The components of this combustion - chamb er design are shown i n Fig . 5. Oxygen injectors are at the r i ght and the Mone l i nner line r of the combustion chamber w ith its spi ra l water - cooling pas sage is at the l eft. The air - cooled i gniter at the l ower l eft is not that whi ch was finally used, and the central fuel -injector rod is not shown. This rod w as difficult to machi ne , since i t involved the drilling of pairs of small holes at such an angle that like - on - like i m pingement w ould occur . Hole alignment was c riti cal, and two attempts were needed to obtain sa tisfactory results . Machi ning of the holes was f i nally done w ith a sonic drill. This compli cated combustion-chamber structure r e quired clos e toleranc es to maintain satisfactory sealing in the var i ous flow passages .

FIG. 5. Initial- Design Combustion- Cha mber Components.

The apparatus, as assembled for testing, is shown i n F i g. 6. The spheri cal tanks conta ining JP -4 fue l are a t the left; the i g niter , h eat exchanger , and var i able no z zle in th e center . The first run e nded in thermal fa ilure of the inner line r and annular piston (Fi g . 7) some 13 seconds after i gni ter lightoff. Thi s design approach was d ropp ed i n favor of a s i mpler , less complicated des i gn that resulted fro m the i gniter development program .

7

NA VWEPS REPOR T 8998

(a ) Chamber Assembly

(b) Chamber Assembly and He at Excha nger

FIG. 6 . T wo Vie ws of Initial-Design Combustion Chamber

Installed Prior to Test.

..

•

N A VWEPS REPORT 8998

..; "' "' [-<

.: 0

tl ;j

..0 s 0 u ~ .~ J.L. k

"' ..., .... < "' ..., .: • "' .: 0 0. s 0 u .. "0

"' bO ro s ro

Cl

r-: () .... J.L.

"

9

NAVWEPS REPOR T 8998 UNCLASSl.~L

IGNITER DEVELOPMENT

Emphasis was placed on the developme nt of an igniter for two r ea sons . First, it had to be dependable before any full- scale combustion development work could be carr i ed on. S econd, using the i gniter w ith fixed flow areas permitted muc h deve l o pment work on prope llant inj ec tion to be done inexpensivel y by using interchangeabl e no zzle s and or ifices .

The f ir st design was a cylindrical chamber , 1 I 4 inch in diameter, w ith singl e j e ts of JP-4 fuel and ga seous oxygen impinging on each other near the e l ectrodes of an aircraft spark plug e n e r gi ze d w ith 20 kv. The nominal propellant flow s we re 1 I 64th the full rates , and the oxygento-fuel ratio was 1 . 5: 1 to mainta in a fu e l- rich m i x ture and a l ow gas temperatur e in the uncooled chambe r. I gnition w ith this apparatus was sporadic and unsuccessful. When the combustion-chambe r d i ameter was enl arged t o 1 . 0 inch, and the oxygen fuel (0 I F) r a tio rais ed to 2. 5, i gnition wa s accomplishe d and sustained combustion achieved w ithout the continuous sparking of the plug . The small inj e ction orifices, however , we r e subj ec t to clog ging, and even partial clogging would deflect the propellant stream so that i mpingement woul d not occur and the m i x tur e would not i gnite .

Two mo r e des i gns we r e tried. One incorporated a splash plate, on w hich the fuel impinge d whil e the oxygen i ntersected the r esulting fan shaped spray. As shown in Fig. 8 , this des i g n uses an uncooled c hambe r of about 1 . 0-inch i nside diameter i n conjunction w ith an aircraft s park p lug. The s econd d es i gn employed a coni cal oxygen inj ection and central fuel - inj ec tion arrangement s i m ilar t o that of a p a i nt - spray nozzle . The components of this inj ecti on h ead are shown at the right of Fig . 9 , a l ong w i th an air - coo led combustion chamber and an automotive spark plug.

The f i nal i gnite r chamb e r made use of thi s conical inj ecto r concept. I n Fig. 10 , the inj ector is shown producing the spray pattern obtained w ith air and wate r. Ne i ther of the f ir st two inj e ction desi gns proved workable, but the coni cal i njec to r gave immedi ate a n d r e liable i gnition under a var i ety of OIF ratios and provided smooth, sustained combustion. An a ttempt at keeping the design s i m pl e , by avoiding the use of water cooling for the c o m bustion chamber , wa s unsuccessful. Stainl ess steel, brass , and copper we re tri e d w ith a va riety of a ir-coo ling f i n patte rns a nd 01 F ratios. Fifteen t ests we r e made , the longest for a duration of 84 seconds b efor e burnout . S eve ral 6 -to- 8 -s econd tests d emonst r ated r estart capability, but sustaine d operation wa s not possible b ecause of thermal f a ilure. A copper chambe r, howeve r, w as operated for 30 m inute s w i thout failure when a small amount of wat e r was sprayed on the fins . The wa t er - cool ed confi gur ation show n in Fig. 11 and 12 was then built. Fi gure 13 shows the thermal damage that occurr ed on the stainless - stee l ver sion of this configuration, in contrast to the complete l y succ e ssful op e r ation w h en it was m a de of c opp er . The assembl y shown in Fig . 12a was used as

10 UNCLA.

•

..

•

NAVWEPS RE PORT 8998

FIG . 8. Splashplate Igniter, Uncooled .

\.1 1.\

FIG . 9. Conica l - Injector Igniter, A ir- Cooled .

ll

NA VWEPS REPORT 8998 UNCLASSI~

(a ) Injector

(b ) Pattern

FIG . 10. Conica l Inj ect or a nd Spray Pattern Using Wat er a n d Ai r.

~ .... -

>--'

vv

•

Cooling-water

inlet (10)

Nozzle

Water out let

Body cooling

wa ter inlet

FIG. 11. Water-Cooled Igniter Assembly .

,\;\;\:\\:\ \:\\~ - inlet

Oil inlet

Injector head

c::

z ~ < ~ M 1:j Ul

!;d M 1:j 0 !;d f--3 Cf)

....0

....0 Cf)


14

(a ) Assembled

(b ) Disa ssembled to Show Cooling Pa ssages

FIG . 12. Wat er-Cooled Igniter A ssembly as Used on Origina l Combustion

Chamber and Modeling Tests.

u SJFI~


(a ) Da mage to Injector

(b) Dam age to Other Components

FIG. 13. T wo Vie ws of Damage to Water-Cooled Stainless-Steel Igniter Components After Test.

the igniter in initial full- scale combustion testing. All parts expos e d to the combustion proces s were made of copp er and were cooled b y water flowing at 0. 3 lb/ sec . Fuel flow fo r this igniter configuration is 0 .0 0731 lb/s ec, inj ecto r d i ameter is 0.047 inch, and injection velocity is 12.7 ft/sec. The oxygen flow rate is 0.0149 lb/s ec , the injection ve locity is 150 ft/ s ec , and the annular injection ar ea 1s 0. 003 in2 . The chamber diame ter is 1. 0 inch, and gas ve locity is about 10 ft/ sec . The exhaust no zzle diameter is 0. 0 63 inch.

15

NAVWEPS REPORT 8 9 98 UNGLASSI FtfOEN~ ELECTRIC IGNITION

During the e arly part of the t e st program, e lectric ene rgy for the spark plug w as provide d by a transistorize d exciter which provide d 20 k v , 10 jou l e s, at 14 pulses p e r s e cond, and was s e nsitive to de viation from the nomin al 24- v olt input. B e caus e of the slow sparking rate, the unit was unsatisfa c tory. Late r tests w e r e made with a high-voltag e transformer from an oil- burner igniter that provided 10 kv and oper-a ted on 110 volts. The s e condary coil of the transformer had a t e nde nc y to burn o ut afte r more than 30 s e conds of operation. A sparking coil used for starting di e s e l engine s prove d the most satisfactory sourc e of hi gh- v oltag e e l ec tric powe r. The unit, about the si ze of a standard automotive coil, is comple tely s e lf-contained and provides continuous sparking at 15 kv w h e n e n e r gi ze d w ith 12 volts d. c. It was us e d throughout the pro g ram.

Standard spark plug s a ll prove d unsatisfa c tory. Aircraft plug s provide d no adv antage o ve r standard autom otive spark plugs, and we re consid e rably more exp e nsive. Multiple starts could be obtaine d in short runs (about l 0 s e conds), but e l e ctrode s burne d a w ay in runs of mor e than l m inu t e . S e v e ral me tho ds we r e considered for obtaining e i th e r ( 1) a n e l ec trical spark w ithout the us e o f a spark plug or ( 2) ignition by means of a hyp e r golic fluid inj e c t e d into the i gniter combustion chamber. The handling of a third storage prop e llant was not attractive, and the introduction of an insulate d, high- v oltag e el e ctrode into the hi gh-pr e ssur e combustion chambe r w ould b e an added sourc e of unreliability. A c o ld, s u rface - gap spark plug w as f o und to give r e liable r e sta rt p e r fo r m anc e aft e r 2 minute s of o p e ration, but s e ldom would last b e yond 5 m inute s. Howeve r, this inexp e nsive spark plug, the Cham pion UJ -1 7V, m ad e for us e w ith outboard e n gine s, was us e d for all subseque nt t e sts a ft e r the gap had b een w ide n e d to l /1 6th inc h b y t urning the outside e l ec trode on a lathe .

The usual m od e of failur e for t h is spark plug w as partial m e lting of the e lctrode s until th e y fus e d to ge ther, shorting the circuit. Va rious pr eventive scheme s we r e a ttempte d:

1. Cooling wa t er wa s allow ed to flow a r o und the plug thr e ads and into the com bustion c h amb e r at a ve ry low rate . (This method w as e ff e ctive but n ot c omple t e ly r e liable b e caus e of irregular wate r flow. )

2. The spark plug w as ins e rte d in a spring -loaded piston that w ould r e tract out of the c o m b u stion z one w h e n c hamb e r pr e ssur e w as e stablishe d.

3 . The spa rk-plug e l e ctrode f ac e w as contoured to fit flush in the combustion c ham b e r so that hot gas circulation w ould not take plac e in the plug cavi ty.

4. Oxygen - fuel r a tios w er e changed to obtain c oole r gas t e mp e ratur e s. W a t e r coo ling ar ound the plug thr e ads showed the most promise of suc c e ss, b u t the a dd e d c omplexity of this de si gn w as discoura g ing.

l 6 u


It was believed that the spark plug could be eliminated by heating the propellants to the autoignition point, thereby making them hypergolic. Since the flow rates are low, approximately 2, 000 watts of electric power (or 1. 9 Btu/ sec) are required to provide continuous heating. Ignition occurs on the initial slug of propellants; therefore, the electric power need be applied for only the first few seconds, for a total energy supply of approximately 9 Btu.

A literature survey failed to reveal previous work on the ignition of hydrocarbon fuel and oxygen by a heated surface. Nevertheless, this method was crudely attempted by winding an electric heating rod around the igniter injector. A thermocouple was ins erted in the injecto r head to measure the metal temperature. The propellants were heated as they pas sed through the inj ector -head flow pas sages. Ignition was suecessfully accomplished by this means at 830, 780, 700, 600, and 400° F. The true temperature of the propellants was not measured, but it can be assumed that they were between 400 and 800° F m order to have ignited hypergolically.

Ignition by heating the propellants externally prior to injection was attempted. The propellants were passed through a copper block e lectrically heated to 870° F. The propellant temperature ente ring the igniter inj ector was 480° F for oxygen and 420° F for the fuel, but ignition did not occur. It was assumed that heat transfer to the metal parts of the igniter cooled the propellants sufficiently to prevent autoignition. For verification, nitrogen was passed through the oxygen line, and the nitrogen temperature in the injector head was found to be 180° F. The head itself was 160° F. A platinum catalyst screen placed at th e injector face did not solve the problem.

Heating the propellants to their autoignition point is the most promising method because it eliminates the spark plug and could eliminate the need for a separate igniter. Hardware for a self-contained heating element in the injector head has been fabricated but not tested. This design should permit temperature monitoring of prope llants directly and should also provide design parameters for other ignition methods to be used in the main combustion chamber .

MAIN CHAMBER WITH CONICAL INJECTION

The success achieved with conical injection during the development of a suitable igniter, and the failure of the initial main combustionchamber design, led to a series of tests using the igniter configuration of Fig. 11. The objectives were to determine (1) the possibility of utilizing this injector configuration as a main-chamber injector, and ( 2) the variation of propellant flow that could be put through a fixed area inje ctor w ithout exceeding a 250-psi propellant-injection pressure differential and still maintain a satisfactory combus tion process.

17


A series of mete ring or i f ic es and exhaust nozzles were fabricated to permit the prop e llant flow to be var i ed from some nominal value as established by the inj ec tor flow area, taking the full 6P of 250 p s i down to 1 I 25th - 1 I 30th the nominal value. A small amount of coo ling wat e r wa s allowed to e nter the chamb er as a diluent to cool the exhaust nozz l e. Run time s were k e pt at a nominal 2 m inutes , sinc e this p e riod was felt to b e sufficient for achievi ng stabili ze d conditions . The results a r e given in Table l.

TABLE 1. Mode ling Test Results

Fuel Oxygen Water C ooling water

Run Chamber flow flo w flow

Oxygen- flow rate, T est

lb/ sec Remarks time , pressure , fue l date

psi rate, rate, rate,

ratio min lb/ sec lb/ sec lb/ sec

Chamber Nozzle

5/21/65 2.0 950 0.010 0,03 95 0.025 3.95 0.3 93 0. 133 ••• • 0

5/25 25.0 880 0.013 0.046 0.075 3.53 0.240 0.220 Durability

test

5/29 2.0 960 0.015 0.057 0.052 3.8 0.378 0.1 91 ..... 5/31 2.0 920 0 .026 0.084 0.160 3.2 . . . .. . •••• 0

6/11 2.0 960 0.0024 0.0066 0.015 2.78 0.465 0.232 Lowest flow-

rate run

6/ 13-A 2.0 840 0.046 0.123 0.310 2. 7 0.550 0.260 ..... 6/ 13-B 2.0 680 0.071 0.149 0.62 2.2 0.550 0.260 Highest flow -

rate run wi th

incomplete

combustion

6/ 20 12 .0 . . . .. . . . . . .. . .. . .. ... T we lve 1-

m inute runs;

resta rting

without dis-

assembly

6/21 2.0 900 0.050 0.138 0.25 2. 8 . . . ... Highest flow-

ra te run wi th good com-

busti on

In each of the ten tests made w ith the all - copper i gnit e r combustion chambe r, immediate i gnition and smoo th combus tion were obtained with no hardwar e damage .

The flow rate was va ried over a range in exce ss of 20: l through a fixed-area inj ec tor. The low e st flow rate for which it was prac tical t o make meter ing orifices gave inj ec tion ve lociti e s of 3.0 ftls ec for fuel and 15 ftl sec for oxygen ve rsus 80 and 400 ftl sec, r es p ec tive ly, for the hi ghest flow rate. The success of this configuration demonstrated that an extr eme l y w i de var i ation i n power level can be achieved w ith cons tant

1 8 UNCLASSI·

•


supply and chamber pressure by using throttling va l ve s upstream of the inj ector . Any reasonable temperature can be maintained by controlling the ratio of diluent water to propellant fl ow.

A full-scale main chamber , shown in Fig. 14, was designe d w ith parameters evolved from the series of modeling tests made w ith the igniter . The ap p aratus is divided into five component groups: combustion chamber , i gnite r, inj ector, meter ing section, and control section. All components exposed to the combustion process are made of copper. All othe r portions of the apparatus are made of stainless steel. The design seeks to minimize structural loads on the inherently weak copper components.

Water enters the r egenerati vely coo l ed combustion chamber b e tw een the copper inner liner and the stainless-stee l water jacket shown in Fig. 15. Cooling water for the igniter is supplied from the main chamber cooling pas sages. Approximately 0 .14 lb/ sec is drawn from the upper portion of the chamber to cool the i gniter combustion chamber, while 0.11 lb/ sec is drawn from the lower p ortion of the main chamber to cool the i gniter nozzle. Orific es are used to control the flow rates . Routing igniter cooling water in this manner provides cooling for the m ain chamber when the igniter is operating and the chamber is not. The remaining cooling water is used as diluent and is ducte d t o the metering section. Oxygen and fuel are ducted both to the metering s ection and to the i gniter . When the main propellant valve s are opened, i gni ter cooling water flows while the fuel and oxygen are inj e cte d into the igni ter combustion chamber and i gnite d b y the spark plug . The propellants are pr evente d from flowing into the main chamber by the closed throttling valves in the metering secti on. The i gnite r r emains burning under cons tant flow conditions ind e p endent of main chamber operation. I gniter components are shown i n Fig. l 6 and the assembly in Fig .l7.

Flow-rate control of prop e llants and d ilue nt is furnishe d by the metering pintles. Each pintle has a tap e red groove with a rectangular c ross section, the area of which is calcul ated to prov ide the correct flow and inj ection pressur e for maintaining a sto ich iometric 0/F ratio and a pr e d e ter m ined diluent-fuel ratio. The quantity of diluent flow depends upon the desired gas temperature . The pintles slide in a metering block who se position relative to them can b e adjusted and s e t for f ine calibration. Pintle position is maintained by a piston w hos e axial movement is controlled by high-pressure w ater through a f ourw ay valve . When a pintl e position is established, the contro l piston is hydraulically locked in place by this valve . T otal stroke of the cont r ol piston-pintle assembly is 1.0-inch, and it r equir e s 20 - 30 seconds to go from closed position to full open. Pintle p os ition is indi c ate d e l ectrically on the control b oard by ( l) percentage of stroke ( l. 0-inch being full stroke) , and ( 2) a reading of l 00%, or full open. Approx imate l y 8. O% open indicat e s minimum flow ( l / 30th maximum). The compone nts of t he metering s ec tion are shown in F i g . 18.

19

N 0

ifw.Jr:e.•."JJ ~ .... ~ ~? ~.

~ r-~

Surface-ga p spa rk plug

Cooling-water inlet

Cooling - water dis

tribution m a nifold

Combustion Chamber Section

Igniter

coola nt

jection orifice (5)

Injector Section

Igniter combustion-cha mber coolant drain

Igniter-nozzle coola nt drain

Oxygen-injection pressure tap

Fuel-injection pressure tap

Oxygen injection (annular)

(1)

Diluent-water distribution m a nifold Cooling- water collection m a nifolds

Dilue!lt-water injection-pressure t ap

Metering Section Control Section

FIG. 14 . Mai n Chamber A ssembly.

, ..

z ~ < ~ M 1:J CJl

~ M 1:J 0 ~ 1--3 (]:) --!)

--!) (]:)

N .......

(a ) Disassembled (b) Assembled

FIG . 15. Stainless-Steel Water Ja cket and Copper Combustion Chamber With Longitudinal

Water-Cooling Pa ssages.

z ~ < ~ M 1:J {/)

!::0 M 1:J 0 !::0 t-3 00 -.o -.o 00

FIG. 16. Water-Cooled Ignite r Used in Conical-Injector Main Cha mber.

FIG, 17. T wo Vie ws of Wat e r-Cooled Igniter , Final Configura tion (Nondivergent AM ZIRC

Copper Nozzle an d Combustion Chamber).

z ~ < ~ M 1:J Cfl

~ M 1:J 0 ~ 1-3 ():) -.!)

-.!) ():)

(a ) With Metering Blocks a nd Metering

Pintles Removed, Looking Towa rd

Combustion Cha mber

. . . ·------ -·-·--- ·---

.. -----·-·----·- --

NA VWE PS REPORT 8998

(b ) Seen From the Combustion Chamber

and Injector

(c) Disassembled

FIG. 18 . Three Views of Metering Section.

23

NA VWEPS REPORT 8998 f

The metered propellants are fed to the injector section-fuel through the center, and oxygen through the annulus. Injection areas are designed to provide the same propellant velocities as those used in the igniter modeling tests:

Maximum Ma ximum

flow rate, velocity,

Propella nt lb/sec ft/sec

Gaseous oxygen 0.752 400

JP-4 fuel 0.223 80

A spacer is placed between the two injectors to maintain a concentric annular opening for the oxygen, as shown in Fig. 19. Diluent water is introduced through five injector holes in the copper combustion chamber downstream of the igniter gas inlet. Maximum diluent flow rate is 1.29 lb/sec.

The 0-ring seals were made of either Viton or metal, for high temperature compatability, or of silicone rubber for oxygen compatibility.

FIG. 19. Fuel and Oxygen Injectors.

24 UN CLASS I flilmENTI=


TESTING OF MAIN CHAMBER WITH CONICAL INJECTION

The igniter for this combustion chamber is an integral part of the combustion apparatus, as shown in Fig. 14. About 50 tests we r e made with the i gniter installed to determine hardware durability, coolingwater flow rates (Fig. 20), and reliability in this configuration.

100 200 300

Wa te r Exha ust Tempera ture, °F

FIG . 20. Cooling - Wat er Flow Rate Ve rsus Exha ust Te mpera

ture for Igniter Body and Nozzle.

Following these tests, the first main chamber firing was made w ithout a v ariable-area nozzle at e ss e ntially atmosphe ric combustion pressure to yi e ld visual obs e rvation of main chamb e r lightoff characteristic s. No problems we r e encounte r e d in i gniting the main chamber with the meter ing pintles open only S.O o/o (l e ss than l/30th max imum flow). A series of tests w as the n mad e w ith the v ariabl e -ar e a noz z le connected dir ectly to the main chamber, as show n in Fig . 21. N one of the nine tests made with this s e tup w as considere d succ e ssful, primarily b e cause the variableare a nozzle w as not desi gn e d f o r the hi gh t emp e ratur e (3000 °F) e ncount e red. Run time s we re 4 to 5 m inute s, and some time s as long as 7 minutes but, despite w ate r c ooling , c onstant a nd r e liable cha mber pressure w a s pr evented b y varia bl e - a r ea n o zz l e comp onent failur e such as nozzle burnout, pintle burn out, and pintl e binding .

T e st of the c ombustion cha m b e r, in c onj unc tion w ith the 12-foot sing l e -tub e h e at exc h anger , s how n in Fi g . 22, w ere very satisfactory. The v ariabl e -ar e a no z zle func tione d prope rly w ith the cooler ( 600 to 1 000 °F) exhaust ga s. A total of 2 6 runs we r e mad e with full chamber pr e ssur e , s even we r e made a t a t mo sphe ri c pr e ssure , and 23 were made with the igniter only .

25

(a ) Seen From Variable - Nozzle End

(b) Seen From Metering-Section End

FIG. 21. T wo Vie ws of Close-Coupled Test Setup.

26 UNCLASSIFifDFIDENTt=

NA VW EPS REPORT 8 9 98

(a ) Heat Exchanger and Variable Nozzle

(b) Combustion Chamber

FIG. 22. Two Additional Views Test Setup.

I FlED 27

Typical pressure data are shown in Fig. 23, whe r e the reference pressure (desired chamber pres sure supplied to variable- area nozzle) and chamber pressure show good correlation at various pintl e (flow -rate) settings. Zero time is taken as the instant the igniter is turned on . A nominal chamber pressure of 1,000 psi was arbitrarily selected, since facility limitations prevented testing at the required operational pressure of 3, 000 psi.

TEST OBJECTIVES

The purpose of this series of tests was to develop satisfactory hardware and to obtain sufficient and reliable data for determining thermal performance. Hardware difficulties encountered were ( l) igniter nozzle durability, (2) spark plug reliability, (3) main copper combustion chamber structural integrity, ( 4) maintenance of reproducible metering characteristics, (5) fabrication of a satisfactory heat exchanger , and ( 6 ) acquisition of satisfactory variable-area nozzle p erformance.

IGNITER IMPROVEME NT

The improvement of i gniter hardware and spark plug performance is discussed in the section dealing w ith i gniter development. The igniter nozzle design was changed from the divergent type shown in Fig. 1 6 to the straight-through nozzle shown in Fig. 17 when hot-gas recirculation in the main chamber caused burnout. Contouring the nozzle exit face to the main chamber wall , ducting nozzle cooling water around the Vi ton 0- ring seal, and using the high- strength alloy zirconium copper provided completely satisfactory results. Since diluent water is not used to cool the i gniter gases, the durability obtained with this apparatus is good testimony to the usefulness of copper , w ith its high thermal conductivity, for underwater devices of this type.

MAIN COMBUSTION CHAMBER

The inherent weakness of copper resulted in distortion of the main chamber when high-pres sure ( 1, 500 psi) cooling water was applied between the chamber and the stainless- steel water jacket at the start of each run. This deficiency became obvious during the installed igniter tests, since high-pressure cooling wate r is supplied to the i gniter whil e the main combustion-chamber pr essure is atmospheric. The distortion caused failure of the water seal at the end of the main chamber and loss of adequate water sealing between the i gniter chamber and its nozzle (Fi g . 14) . Ultimately, the latter failure resulted in the destruc tio n of all test equipment when, at the start of one run, the i gniter filled with high-pressure water so that it indicated full i gniter pressure when there was no hot p~lot light.

S e veral copper chambers with different water- passage designs for increased stiffening were constructed, but none maintained adequate dimensional stability. The design was changed so that cooling water

28 u N CLASS I Fl E&FIDENTIAL

-.., -rn C2

N -..o

1,200

1,000

.~ 800

"' 0.

oi 600 ~ "' "' <l)

"' p., 400

200

0

s::- 100 .~ ~ .~ .8 "' ..., 0 •M 80 p., 0 ~p., !::! s:: 8 ~ 60 ..c: 0

f-< I ...-<

C! ;; ~I.<.. 40 ...-< '+< <l) 0 0.~ 8 0

p., 20

0

0

0 Main chamber pressure

A Reference pressure

0 Igniter chamber pressure

0 Propella nt throttle position

100 200 300

5 min

Time, sec

400 500

FIG. 23. Variable-Flow Hot - Gas Generator; Typical Test Data : Pressures.

600

10 min

z ~ < ~ M 1::! (/)

!:0 M 1::! 0 !:0 t-3 00 -..o -..o 00

NAVWEPS REPORT 8998 u N CLASSI flffiwo:HTIAJ/

was ducted internally through the main chamber to preclude the existence of external pressures. When hardened z irconium copper alloy was used, there was no distortion at all around the water seal in more than 50 sudden applications of 3,000-psi water. In time, however, the forward end of the chamber (around the ignite r) distorted sufficiently to cause widened clearances in this tolerance-critical area, as well as loss of water sealing in the igniter chamber. Figure 24 shows another chamber constructed of this alloy and design, with the addition of a steel stiffening ring in the forward end of the copper chamber. The longitudinal water holes were gun-dr illed and sealed at the end w ith L ee plugs. Although it was not used in actual combustion tests, this type of construction provided a sound structure for hydrostatic tests.

The choice of copper or copper alloy for combustion chambers is limited to those alloys containing 98o/o or more copper if the high heatconductivity advantage of this metal is to be maintained. Copp er generally exhibits poor creep characteristics and even when it is work hardened to reasonably high strength (equivalent to common 300- series stainless steels), it will distort under continuous high stress. Moreover, the annealing of elect rolytic tough pitch (ETP) copper occurs at comparatively low temperatures (400° F), and plastic creep is aggravated with temperature increase. Work-hardened zirconium copper or chromium copper alloy improves both annealing-temperature (700°F) and creep- strength properties, whil e it also provides thermal conductivity comparable to .STP copper. The alloy also demonstrated excellent compatibility with hot, gaseous oxygen. There were no burn spots or surface erosion of the combustion chamber .

METERI NG

Difficulty in (1) reproducing run-flow rates similar to those obtained in pre- run calibration and ( 2) supplying adequate oxygen flow at high throttle settings (greater than 60% of stroke) were major problems en countered in the metering section. Desired flow ratios are shown in Fig . 25, along with the theoretical flow-rate ratios that can be obtained with straight- slotted pintles. Actual flow rates and ratios that deviated from the theoretical are shown in Fig. 26. As the test program proceeded, techniques for flow control improved, so that w idely varying mixture ratios (0/F = 1 - 15) were held closer to the desired stoichiometric ratio. Flow-rate data obtained at low throttle settings lack accuracy, and ratios calculated from these data are unreliable ( see the section entitled 11 Facility and Instrumentation 11 below).

The typical metering orifice is formed on three sides by the pintle slot and on one side by the inside diameter wall of the meter ing block, as shown in Fig. 14. An early design used an 0-ring in the meter ing

NAVWE PS REPORT 8 998

(a ) Show ing Gun- Dri lled Cooling Passages

(b ) Showing Steel Reinforcing Ring

FIG . 24. Hard AMZIRC Copper Combustion Chamb e r.

31

-, ______ _ Desired ratio - - --

Desired ratio Oxygen/ fuel

__ j __

10 20 30 40 so 60 70 80 90 100 Percent of Stroke

0 0 . 1 0 .2 0. 3

Pintle Movement, in.

FIG. 25 . Ca lcula ted a nd Actua l Oil/ Fuel and Diluent/Fuel Rados

Versus Pintle Movement for Va riable-Flow Combustion Cha mber.

block for pos i tive s e aling action in the full closed position. T h e 0 -ring prove d unreliable i n formi ng one e dg e of the m eter ing orifice and was r e place d w ith a l a pp e d m e t e ring blo ck - pintle combination w ith a max i mum diametric cle aranc e of 0 . 00001 inch. The close to l eranc e provi d e d satisfactory s e aling i n the closed-throttle position, and dele tion of the 0 - ring improved the mete ring r e p r oducibi li ty. Additional hardwar e change s included v arious pintle configurations othe r than the slotte d d e sign, enlar ge d flow passages in the m e t e ring secti on, and a more r e liable m e tho d of a d justing the m e t e ring b l ocks during calibra tion. Flow - rate c ontrol, m i x ture r atio, and ade quacy of ox ygen supp ly ( 0 . 5 lb / s e c achieve d v e rsus 0.75 lb / s e c d e sired) we re impro v e d as t e sting proc ee d e d, but sti ll w e r e far from satisfactory. A cavitati ng v e nturi e ff e ct m a y exist i n the liquid prop e llant flow passage s dur i n g calibrations and may b e the cause of incons i stent fl ows at any given throttle s e tting . Calibrations w er e made w ith a prope llant supply pr e ssur e of 250 psi and w ith the liqui d exhausting at atmospheric

32 C l~GLASSIFI~L

v.> v.>

( ·

"' .s ... <11 ..... r:t:

C1J ..... ::l C1J

"'" ::l 0 ~ <-: 0 ... ... C1J

il .~ :-9 C1J

::l >< :;:: 0 Q '1:l

1:1 <11

ci' .s 1:1 ... .8 ';;;! .~ 0 C!l p,.

C1J p,. ..... 1:1 ~ C1J

0.. l1 0 f-. I :::: ... ;:j

~ "'" :::: ..... C1J 0

~ '* ... p,.

10

8

6

4

2

0

100

80

60

40

20

0

0 Diluent-to-fuel ratio

0 Oxidizer-to-fuel ratio

0 Desired stoichiometric

oxidizer-to-fuel ratio

0

1 I l

0 00 0

0 Propella nt throttle position

100 200

Desired diluent-to-fuel ra tio

~- I

~ I

' I

oG ; 0 ¢0 ¢ ¢ ¢ ¢ ¢ ¢

o A,o o 0 0 0 0 00

0 0

300 400 500

5 min

Time, sec

FIG. 26. Variable-Flow Hot-Gas Ge nera tor; Typica l Test Da t a : Mixture Ratios.

600

10 m in

z ~ < ~ M 1:J (/).

!:!:1 M 1:J 0 !:!:1 1-:3 CXl ._!)

._!)

CXl

NA VWEPS REPORT 89 9u N cLASs 1 F 1 E o NFIDEt!-l:.I .. J-r.

pressure-that is, at pressure conditions different from those which existed during burning tests. At that time, calibration methods were being modified to lead to an improved throttling system and better propellant flow control. An improved and developed metering section might prove to be superior to variable flow pumps. Further development work on this part of the apparatus is required.

One of the critical flow-control variables is the propellant pressure supplied to the metering section. All propellants were controlled by flow regulators that maintained constant pres sure to the metering section independent of flow rate. Inaccurate regulator settings caused small differences (±30 psi) in the supply pressure (nominally 1,250 psi). This, coupled with a chamber over or underpres sure (1, 000 ± 50 psi), caused flow variations from pre-run calibrated values. Differential pressures varied as much as 80 psi from the nominal desired value of 250 psi during the course of a run. Techniques and hardware to eliminate this source of flow- control error also require further attention.

HEAT EXCHANGER

The heat exchanger , or combustion-chamber extension, is intended to simulate the steam boiler, provide cool (400 ° F) exhaust gas for variable-nozzle development, and determine the effect the steam boiler may have on the combustion proc ess . The first approach to providing a heat exchanger was the 12-foot-long assembly of 79 quarter-inchdiameter stainless-steel tubes shown in Fig. 27. The front assembly consisted of two sheets with high-pressure diluent water flowing between them. The tubing was rolled and furnace- brazed into each sheet. By keeping the diluent inside any thermal failure between a tube and the fire side of the front sheet would spill diluent water into the combustion chamber, thereby protecting the rest of the exchanger from hightemperature combustion gases and loss of exchanger cooling water. The downstream end of the tube assembly was brazed into a piston that is allowed to slide in a cylinder, compensating for thermal expansion. Cooling water supplied by a pump at 140 - 1 60 gal/ min enters through a multiple-holed water -distributor ring, which impinges on the back of the front tube-sheet assembl y .

The first heat-exchanger assembly, shown in Fig. 28, was partially destroyed during tests of the first combustion c hambe r. The remaining tubes were reassembled in a 6 -foot l ength (exhaust temperature about 600° F), and put into service with the conical inj ector chamber.

A theoretical analysis of temperature distr ibution on the face of the front tube sheet of the multiple-tube heat exchanger showed that the metal temperatures would be close to the melting point. Gas temperatures and water temperatures were also calculated for the 12-foot multiple-tube heat exchanger in this analysis and are shown in

34 u N CLASS I Fl ElfF~TIAL

..

..


Diluent-water outlet {to combustion chamber)

Cooling-water inlet

Ga s

flow \

cha mber

Diluent- 1\·:n er inlet

Front tube sheet

Back tube sheet

Ba ck tube

sheet

Thermocouple well

C oo li ng- w:.t ter distributor

(a ) Combustion - Cha mber End

Stain le ss-

Copper- brazed jo int 733/ 4in.~

Copper-braLed joint

_ \: i~~~:-.,_,·~~tee l 3

•

16

P~iston 79 Sta in less - Stee l 304 tubes; separat ors a t approx i-

0.2 52 OD, 0.035 wa ll ma tely 19-in. interva ls

(b) Tube Bundle

FIG. 27 . Mult ip le-T ube Hea l Exchanger.

FIG. 28 . M ultiple St ainless-Steel-Tube Heat Excha nge r (12-ft ).

35


Appendix A. Since the structural re liability , as bas ed on this analysis, was margi nal , the first test was made at parti al throttle and atmos phe ric pr essur e. The result was tube distorti on from d ifferential ex pansion of individual tub e s and l oss of s e a ling integrity at the braze d joi nt on the front tub e sheet , as shown i n Fig. 29 .

A s ingl e copper - tub e h e at exchange r ( exhaust temperature about ll 00 ° F ) was constructe d (Fi g . 30). E x p e rience w ith copper combus tion chamber components inspir ed greater confidence in the structural reliability of this design . This confidence proved well ground ed, since t he h e a t e x change r wa s us e d for the r emaind e r of the test program w i thout structur a l failur e.

(a ) Tube Bundle 1\fter Run a t 1 Atmosphere, Showing The rma l D a mage

(b) Tube Sh eet A ft e r Run a t 1 Atmosphe re , A lso Showing Da m age

FIG.2 9. M ulti ple - T ube H eat Exchang er (6- ft ).

3 6 u N CLASSJ fliDIDE~Ii\t

-..,

cv ~

Cooling - wa ter

d istributor

Ga s flow

..

! Cooling- water inlet

/

Thermocouple well

r.- l! 1: !1 . ~

" ~~

. ·. \ ·.· ·~ .. \...\ \U\ .-n. , . ~ \llillillillSiiiiiTI\iiii\i:t~/ i ! S I

j

L, Copper tube

FIG. 30. Single-Tube Heat Exchanger.

Piston

Cooling-water out let

z > < ~ M 1:J (fl

!Jj

M 1:J 0 !Jj

t--3 00 ...0 ...0 00

NAVWEPS REPORT stJ N CLASS I fl EOoNFIDEN'fh'<L VARIABLE-AREA NOZZLE

Obtaining a satisfactorily performing variabl e -ar ea nozzle was an essential part of the development program, since a suitable nozzle is required for proper testing of the combustion apparatus. D e sign parameters e stablished for the test nozzle can be used in any practical powe r plant application. The nozzle must maintain the de sired com bustion- chamber pres sure constantly and automatically while the total flow rate is v ari e d over a w i de rang e , and it must operate at temp e ratures up to l 000 ° F.

The first variable-area nozzl e ,uncoole d and d e signed for operation at 300 to 400 ° F (shown as a drawing in Fig . 31 and in the actual assembly in Fi g. 6) , was abandoned as inadequate . The second noz z le (also show n in Fig. 31), desi gned for 1000° F operation, w as w aterc ool e d and p e rformed satisfactorily in all tests except those that were directly connected (the test setup is shown in Fig. 21 ) .

Typical no zz l e damage incurr e d during dir e ct-connected t es ting is show n in Fig . 32. The carbon no zz l e and pintle we re quickly attacked by hot steam and unreacted oxygen. Components made from Inconel alloy fared no b e tter . Binding of the pintle due to the rmal expansion wa s a problem in each of these runs. S eve ral remedial ste ps we re taken to obtain a satisfactory clos e - coupled test: ( l) use w as made of a nose pie ce for the pintle made of tantalum and surface -tr eated by a Chromalloy process for protec tion fro m the oxidiz ing combustion gases ; ( 2 ) cooling was effec t e d with wat e r flow ing through the center of th e pintle and i n to the combustion ga s es (the water flow , suppli e d from the diluent source at a c onstant 0. 0 64 lb/ sec, do e s not interfere with p intle movement); a nd ( 3 ) extra-wide clea ranc e b e tween the pintle and the b ear ing surface of the c ontrol section wa s a llowe d. These modifications to the variable - area nozzle we r e not tri e d in a directconnec t ed t est. The modifi ed nozzl e ass embly shown in Fig. 33 was used satisfactorily in all the tests invo l v ing the heat exchanger .

One measur e of the nozzle's ability to p e rform is the r e spans e of chamber pressure to changing flow rates. Another is the correlatio n b e tween reference pr e ssur e and chamber pressure. Typical p e rformanc e of th e nozz l e is shown in Fig. 23. The refer e nce and c hambe r pressur e s are in c los e agreement (w ith a c onstant 30-psi diffe r ence ) ind ependent of throttl e position. The no z zle maintained full chamber pressure dow n to a throttle position of S.Oo/o , which provides a flo w rate less tha n the minimum required. R e sponse to c hanging mass fl ow is sufficiently rapid that no detectable lag ap p ea r ed in chamber pressure.

38 UNCLASSIFI~

-n -rn

lN -.0

Gas flow

Pintle

Regulated

Origina l Design

C o pper

wa sher

Chamber

Lee plug

FIG. 31. Va riab le -Area Exh a ust Nozzles .

Pintle

Exha ust port

(4 places)

Control section

F ina l Design

Reference

pressure

z ~ < ~ M 1:J Ul

~ M 1:J 0 ~ r--3 co -.0 -.0 co

NAVWEPS REPORT 8998u N cLASS I EIE=D·Fll'll!:!<ITIA~

(a ) Carbon Nozzle a nd Pintle Before a nd After Test

(b)Actuating Piston, lncone l Nozzle , a nd Bronze Bushing

(c ) lncone l Nozzle, Bronze Bushing , a nd lnconeJ Pintle

FIG. 320 Va riable-Area Nozz le Damage After Close-C oup led Testing .

40 u N CLASSI F-J&&M l'IAL

UNGL.rASSIFIED NA VWEPS REPORT 8998

(a ) Showing Pint le and Nozzle

(b) Showing Exhaust Ports

FIG . 33. Variable-Area Hot - Gas Nozzle Assembly .

. I· 41

NA VWEPS REPORT 8998 UNCLASSI~rTIAI

FACILITY AND INSTRUMENTATION

The facility and instrumentation used in testing are show n schematically in Fig . 34. Oxygen was supplied from a manifold bank of 33 Ksize gas cyli nders , remotely located, in w hich 50. 8 cu ft (wate r volume ) of gas w as stored at 2,200 psi. Minimum usable oxygen pr essure was l ,400 psi. Nitrogen was used to pressuri ze the JP-4 fuel supply, whi le comp r essed a ir wa s used for pr essuri z ing the diluent-water supply tank and for operating all controls (val ves , regulators, etc . ). About 18 7 gallons of fresh wate r was avail able to provide the diluent, to cool the variable-nozzle pintle and igniter, and to actuate the meter ing control section. A centrifugal pump suppli ed lake water fo r h e at-exchanger cooling. Because of the limited oxygen-supply pressure, main-chamber tests we r e kept at a nomi nal 1,000 psi. Run times were restricted to less than l 0 minutes to assure an adequate supply of diluent water.

The fl ow and p ressure r egulators used we re manufactured by the Grove Co m pany . Manually operated pr essur e re gul ators in the control room we r e manufactur ed by the Airvalco Corp., S an Gabri e l, Calif., and the Grove Valve and R egulator Company, Oakland, Calif. All flow v alves , both hand- and a i r - operated, we r e of the ball var i e ty manufactured by the Jame sbury Corp., Worceste r, Mass . F low lines were of 1 / 2-inchdiameter stainle ss- steel tubing , except for the o xygen line , which was 1 . 0 inch i n diameter, and the lines to the ignite r, w hich were of 1/ 4 -inch diameter. All line s, valves, and r egulators in contact w ith oxygen were made of stainless s tee l, Teflon, or s ili cone rubber and kept scrupulously clean. S eve r a l oxygen -line blow outs were attr ibut a ble to fore i gn matter , probabl y fuel or o il, in the line. The source of ignition in th e se blowouts was not established. In one instance , the T eflon seat of the oxygen val ve had to b e rep l ace d b e cause of wear. All other components o p erat ed sati sfactorily throughout the test period. The data gathered were intended to pro vid e sufficient and accurate measurements of va riabl es to enabl e a heat balance to b e calculated, to determine effi ciency, and to provide design data. S eve ral attempts to calculate combus tion effici e nc y b ased on a h eat balance were unsuc cessful b ecaus e of insuffici e ntly accurate data, c hie fly in measured flow rates. Four kinds of informa tion were gathered: pressure, flowrate, temperature , and position.

42

The following pressure measurements we re made:

1.

2.

3.

R eference pressure supplied to the var iable nozzle and controlle d from within the t es t ce ll Mai n - chamber pres sure, whi ch responds to t he reference pr es sure I gnite r- chamber pr es sure, whi ch is influenc ed by the i gniternozzle flow a r ea and flow r ate and also prov ides the " go - a h ead 11

s i gna l for the test operator to proceed w ith actuating the metering section of the main chamber

UNCLASSIFIHtiDEN~

..

"

U~'bASSIFIED

lEGEND

5'{Pv1 . ITEM RA NG E.

roxBORO RECORDER Ao\1 0 CO"--TRO LLER

Cl 0 B ~ 0

G A G E ~-~~ PSI LOG SCALE

~ ~ rd i

C HECK VALV E

HAND VALVE

OR IFICE.

D/P CELL PNEUMATIC.

C.ONTROL VALVE

SOLENO ID

VALVE

AIR O PERATED VALVf

c::c::::::::J SWITCH

ca

~

HAND LOADER

REGUL.ATOQ

(---- -)

0 GAGE

~ TRANSDUC ER

(!) 1000- 5 CXJO P SI

@ 0- 1000 PSI

(j}O-~ PS I

@ 0 - 50 P51

@

<D 1000- 5000 Ps 1

@ 0 - 1000 PSI

@ Q -!oO PSI

@ 0-I SO PSI

EL ECTRIC DATA OUTPuT

Q) O - 5000 PSI

®0- 1000 PS I

@ 0 -600 P S I

\1) 0 - 10 0 PSI

@ ELE<.TRIC.

Q) 0 - 20 P.S I

CD o-sooo PSt

G)

@

§!) DIFFERENTIAL TRANSDU CER

(ID TURBINE FlOW ME T ER

c:::J THERMOCO U PLE Q) 5() - KX>•F

{!) 70 · 250•F

® 500 - 1500 .. F

® 50- 2.S O •F

NOTE :

--I.- A L L INSTRUMENTATION AND CONTROL LINES -*'SSTUBE -o•

2 . ALL F L OW LINES - 2 S S. TUBE .

3. ALL O XYGEN EQU IPMENT CLEANED BEFORE INSTALLATION.

4 . ALL HAND VALVES ARE .JAMES B U R Y B A LL VALVE">: SS AND TEFLON.

I FlED


~ TEST PIT Ai<E A

CD OX YG EN STO QAGE

Ql--(t>t:OOPs l )

l_--~~~:_--~~----~~~~~~}-__________ _J--~~--~~- YE~T DI LUENT WATER

~ - -t ::::-::-:::: ::.;: :.:-_-_-J:

: HT. EX .WATER, : r --- - -------

i : : : FUr~~~~~P-~-

, ' ' : I

i ' ' I

OX.. FLOW r ---- - - ~-

~ I

1 l ' ' !

(_ _________ _ ------ ------ -. --

TURBINE FLOW METEQ

ER.TERS

~ I OXYC>EN OP

~ DIUJENT W"TEJ< DP

'-- FUEL FOXBORO DP

r-------1- OX. H O W PRESSURE - HT.E.IC WATER TEMP. IN - HT. EX.WA"TEQ T EMP. OVT

r-'-'-'-.-1-- t-iT. EX .WATEQ FLO W RATE. E.'(HAUST CIA'S TEMP.

FVEL INJ . PRESSURE - WAT E.Q llW . PRE SSU RE

OX. INJ . PRESSURE FUE L F LOW RATE D4LUE.NT f"L OW RArE: or now F?A.TE.

'------f- C~HBE~ P R E S":.UR E.

OX . FLOW

RECOQOIN G PA#JEL

IGNIT ION

SIREN -------t-

OX. FOX80RO OVTPUT+-1---- -

0/LVENT WATER I FOX 80RO OUTPUT

FUEL FO><.BORO OUT PUT ---®

VISV A.l Q._ ... ...,,....,"""

[5)

,seffi

t=VE.l O IL TAN K 4 F"Ts

N ITR06EN STORAGE 0 ~

TO CONVERTER: - - :

T O FOXBOR O C.ONTROLl.EQ

t,C.AGf

OXYCE.._. IN.Jii:CT IOW P R.ESSURI!.

r SOO PSI

~VENT

VENT

500 P SI

r-- FUEL INJECTION PRI!~S.UQE

I

SOOPSI- ~ J t

;·~::::,:;:_ I

H Oil-.....,1Xf--VENT 500 PSI ~ j W ATER INJE:C.TION PRE'S5UR.E

WATER

OUTPUT TO FO XBOR:O ( Qt.JTROLLEQ f. PANEL GAGE

CONVERTER I

:;:;.,

20PS I

' D I L UE N T WAT ER (AL.L F"L O W =tEl t----,;-U I INSTR U MENTATION IN THIS LINE)

DILUENT W ATER METERING S ECTION

TANK

F" ILl. _ rb__ ,!-,.

VO>I"'"

tENT

~

( OPEN WHEN PRES~ R f"ZIN6)

1.74 · 9 .30 G P"""

FRO M FUEL VALVE

INJE CTOR S ECTION

v;-7 L__DILUENT e c OOLING

W ATER:

' 1-l lb H TENS ION L E.A.O 0 2 0()0 VO LT S MIN.)

FIG. 34. Instrumentation and Fl ow Schematic for T est Pi t.

43

NAVWEPS REPORT 8998

4 . Fuel -injection pr e ssure, or pr e ssur e just dow n s tr e a m of the metering section, prior to enter i ng the main chambe r

5. Gaseous oxygen injection pressure 6. Diluent-water injection pres sure 7. Pressure at the oxygen flowmeter, for calculating d e nsity and

flow rate

The fo llowing flow-rate measurements were made:

1. JP-4 fuel 2. Gaseous oxygen 3 . Diluent wat er 4. Heat- exchanger wat e r

The following temperature measurements were made:

1. Temperature of the oxygen gas at the flowmeter for d ensity and flow- rate calculations

2. Temperature rise of heat-exchanger cooling water for heatbalance calculation

3. Diluent-water temperature 4. Igniter combustion-chamber cooling-water temperatur e and

nozzle coo ling-water temperature 5. Hot-exhaust temperature at nozzle end of heat e x change r 6. Combustion- gas temperature

Pintle position was measured as a percentage of the total stroke. Various additional data we r e taken during some tests to meet spec ific test objectives.

Pressure measurements were made with electric strain gage -type transducers , and calibrations were made before each run. Flow-rate measurements were made with turbine-type flowmeters to get the w id e st possible range of flow measurements without r e sorting to double instrumentation. Flow- rate data below 1/ 1 5th maximum, however, are c onsidered unreliable. Additional flow- rate information was obtained f rom differential-pressure orifice meters to corroborate data taken w ith the turbine meters.

T e mperatures were measured w ith copper-constantan, ironc onstantan, or Chromel-Alumel thermocouples, depending on the r ange of temperatures measured. The thermocouples usually were enclo se d in stainless- steel sheaths w ith magnesia insulation. Figure 35 s how s some of the gas temperatures measured during a run. The adiabatic flame temperatures were calculated as shown in Appendix C. A the r m ocouple (Aero R e search) made of iridium/ 60% rhodium-iridium in a Chromalloy -coated molybdenum sheath was used for measuring the main c o m bustion-chamber gas temperature. The the rmocouple burned o ut, h owever , when the gas temperature exceeded 3000°F due to ins uffi c i e nt diluent-water flow.

4 4

p ~~ u CLA-SS I~

·-.

en --n -rn =

.p.. Ul

4,000

3,000 [..L, 0

GJ~

3 2,ooo

~ I 0.. s GJ

E--<

1,000

0

100

>1~

.2 >1

.';::: .2 80 "' 0 .<;:::

0.. "' 0 GJ 0.. ...... jj >1 60 0 GJ ... 0.. ~ 0 E--< 1 ...... 40 'i:! ......

;::l

~ [..L,

...... .... GJ 0 0.. 20 0 * ...

0..

0 0

\\

A Combustion t e mperature (estima t e d

a dia ba tic fla me tem perature )

'\l Combustion temperature (thermocouple

uncorre ct ed for rad ia tion losses)

<:) Exha ust gas tempera ture (thermocouple)

0 Propellant throttle position

100 200 300

5 min

Time, sec

400 500

FIG. 35. Variable-Flow Hot-Gas Generator; T ypica l Test Data: Temperatures .

600

10 min

z ~ < ~ M '-o (/)

!::0 M '-o 0 !::0 t-j

CXl --o --o CXl

NAVWEPS REPORT 8998 lJ N cLAss lff!!'l'lltL The propellant valve-pintle position was measured by a linear po

tentiometer attached to the metering- section control piston.

RECORDED AND DISPLAYED INFORMATION

Signals from pressure transducers, thermocouples, turbine flowmeters (through converters), and the metering- section pintle position we r e recorded on an 18-channel oscillograph (Consolidated Electrodynamics Corp. ). P e n recorders (Fox boro Corp. ) we re used to record signals from differential-pres sure flowm e ter s.

Visual displays we r e made of some pressures (chambe r, variablenoz z l e referenc e , propellant supply, gas pr e ssure to propellant tanks), t emp e ratur es (exh aus t gas, heat- exchanger water exhaust, ignitercooling water ), and the pintle position. An 11 overflow 11 indicator light was used to warn of an exce ssive flow rate (indicating some sort of anomaly) for each of the thre e propellants. The visual information wa s used to indicat e the progress of the test and adjustments that should b e made during the test.

CALIBRATION S

Pressure-transducer calibrations we r e made with a dead-weight pr essu r e tester prior to each run. Thermocouples we r e calibrated by r eplacing the measur ing junction w ith a millivolt source of the same imp edanc e and i ntroducin g signals corresponding to the desired calibration t emperatures. C a librations were corroborated by separately immersing the measuring junction in i ce wate r, boiling water, and hot oil. Liquid flowmeters we r e calibrated by weighing timed flows of the appropriate liquid.

The turbine meter and venturi for measur ing the flow of gaseous oxygen were calibrated w ith pro ving nozzles in series with the meters through whi ch a calibration gas (gaseous nitrogen) was discharged. During calibration, pr essure at the meter was maintained in the range encount e r ed in use ( l, 200 to l, 300 psi g ). Flow through the proving nozzles during calibrations was choked, and mass flow rates were calculated using a nozzle coeffici e nt of 0. 99. The no zz l e coefficient used was verifi ed by d is c har ging ga s eous nitrogen from tanks of known vo lume through the nozzle and comparing the calculated amount of gas dis cha r ged from the nozzle w ith that removed from the tank . Some scatter ing was encountered in the discharge-coefficient measurements because of difficulty in obtaining isothe rmal conditions in the nitro ge nstorage tanks . The r esults of these calibrations we r e ( l) g raphs of ga l vanometer deflection ver sus volumetric oxygen flow for the turbine meter and ( 2) venturi coefficients for the ventur i meter.

4 6 UNClASSIFfEtrNTt~

I FlED NAVWEPS REPORT 8998

CONCLUSIONS AND RECOMMENDATIONS

During the combustion- chamber investigation at NO TS, an apparatus wa s designed and developed that is capable of generating hot gas under variable-flow conditions. The system appears to have considerable potential value for the chemically fueled power plants of future antisubmarine manned submersibles.

Of particular interest was the durability achieved in construction. In the course of 26 combustion tests, no deterioration occurred either in the high-temperature region of the main combustion chamber upstream of the water injectors or in the igniter chamber , which was operated without diluent water. A h eat exchanger fabricated from a single copper tube p e rforme d throughout the tests without structural failure.

Critical operation of the combustion chamber occurs at the low propellant-flow rates, where heat transfer through the chamber wall is essentially the same as at higher flow rates, and where regenerative cooling-water flow is at a minimum. Continuous operation under these conditions did not adversely affect the equipment. Moreover , combustion temperatur e often exceeded the design maximum of 3000° F, indicating that the gas generator can be safely operated at higher temperatures.

The combustion process was smooth throughout the entire range of flows tested with a conical injector configuration-even at flows below the minimum required.

No r e liable estimate of combustion efficiency based on system heat balance could be made. This is attributed to small errors in propellant flow-rate measurements which in turn provided erroneous adiabatic flame temperatures and heat-release rates. These errors became more significant at smaller flow rates.

The effic i ency of the var iable-ar ea exhaust nozzle design was confirmed during the combustion tests when the nominal chamber pressure (1,000 psi) deviated less than 10 psi throughout the entire range of propellant flows tested.

The nozzle used in this test program provided dependable performance, both in material durability and response, when used with the heat exchanger. Adaptation to specific uses may require some redesign to r educe weight.

Reignition after several minutes of sustained operation was marginal, sometimes occurring, but more often not.

I 47

NA VWEPS REPORT 8998 u N CLASSI rl~D~ITIA-L

The most promising method of ignition and reignition involved heating the propellants to the autoignition temperature, which might make it possible to eliminate the need for a separate igniter, and thus war rants further investigation. If reignition is not a design consideration, satisfactory and reliable i gnition can now be obtained from a spark plug. Reignition w ith the spark plug would requir e further development effort. Other ignition methods are also possible for a single-shot design (i.e., pyrotechnics). Whatever method is used, a continuous pilot flame is necessary to insure that an explosive mixture of fuel and oxygen does not accumulate in the voluminous boiler.

The propellant meter ing or throttling system used in these tests requires more development work to secure flow rates during burning tests that match those obtained in pr e-run calibrations.

'

..


Appendix A

HEAT TRANSFER ANALYSIS OF M O RAY COMBUSTION- TEST HEAT EXCHANGER

The Moray test heat exchanger was designed and built to de t e r m ine the effect on combustion in the Moray powerplant when the b o ile r i s added to a gas generator , producing a large characteristi c c h ambe r length. The exchanger consists of a bank of 79 l / 4 -inch-OD stainle s s steel f i re tubes, 13 feet i n length and enclosed in a 3-3 / 8 -inch-ID s tee l water jacket. Seven equally spaced tube separators doubl e a s coo lingwater flow baffles. Figure 36 is a schemati c diagram showi ng a f i re tube , the combustion gas and cooling-water flow rates , and calcu l ated extreme temperatures.

The object of the heat-exchanger thermodynamic analys i s w a s two fold i n nature. First, due to the high combustion- gas temp e r a t u r e (3 000° F) and the melting temperature of the heat-exchanger m ate ria l s ( s lightly above 2500° F ), the l ocati on and magni tude of t h e hi gh e st s u r face temperature had to be determined. S econd, the axial temp e r a t ure d i str ibutions of the gas and cooling water were required, so that t he proper range of thermocouples for the test m i ght be cho s en .

Because of the h i gh gas temperature , the front tube sheet i s watercooled on both sides . This is accomplished by placing a t h i n , fal s e tube sheet in front of the main tube sheet and pas sing d iluent wat e r b etween them. It was felt that the highest sur face tempe rat ur e woul d b e found on one of the sheets and , that, practi cally s p eaking , a ll the ex change of heat would take place on the after side of the main tub e sheet . For these reasons , the tube-sheet section and the fi re -tube sec tion were analyzed independently.

The axial temperature distribution in the main body of the heat ex changer was calculated, using the parallel flow heat-tran sfer meth od outlined later in this appendix. The tube- sheet section was analyzed by using the heat - transfer - in- ext ended-surface approach. The r eason for employing this approach is also discussed later in thi s appendi x.

Because of the indeterminate flow path of the co o l i ng water , t he fo l lowi ng assumptions were made.

1. All tubes transmit heat equally. 2. H e at is transferred uniformly to the cooling water.

49

Ul 0

c:: z n ... > ~ ~ ~ -,=-, -

Diluent water

to c ombustion

cha mber, ::::

'F~

Inlet-cooling water,

18 lb/ sec, 700F

~ Inlet gas , 2.364lb/sec m

3000° F , 3,000 psi

Lll Fa lse tube sheet

Diluent wat er, 1.29 lb/ sec ,

700 F , 3,250 psi

p

:

Exha ust cooling

water, 303°F

~I

I j

1 of 79 fire tubes

FIG. 36. Schematic Diagram of Mora y Test Heat Exchanger.

4

Exhaust gas,

:::: 308°F

z ~ < ~ M "d Ul

~ M .. "d 0 ~ r-3 00 ,_!)

,_!)

00

NAVWEPS REPORT 8998

3. The cooling water is under sufficient pressure to prevent boiling.

4 . The h eat lost through radiation and convection from the outside surface of th e exchanger is negligible.

The r e sults of this investigation are shown in Fig . 37 and 38. The highes t t emp eratur e computed w as on the inside surface of the fire tubes midway between the front and rear surfaces of the main tube sheet. This t emp e ratur e wa s between 2400 and 2500° F. The water side surface of the tube she e t was computed at less than 900 ° F. Stainl e ss steel begins to m~lt at slightly over 2500 ° F, and looses much of its structural integ rity above l500 ° F. As the tubes are supported by the main tube sheet at the point of maximum t emperature , failure is unlikely.

The t emp e ratur e of the cooling water as it exhausts from the heat exchange r is well above the atmospheric boiling point. If it is desirable to lower this temperature to less than boiling, the water flow rat e must be incr e ased to at l east 33 lb / sec.

As the ga s pr essur e is decreased , the thermodynamic properties w ill b e changed to de c rease the rate of heat transfer. This w ill result in spreading the axial t emperatur e distribution farther down the tubes. The exhaust t emp e ratur e s w ill not be altered appreciably. Therefore, sim ilar r esults can be expe c t ed w h e n operating this apparatus at 1,000 psi gas pressure.

Sub s equent to the heat-transfer calculations, it was found that the heat lost to th e atmosphere through radiation and convection w as less than 0.1 o/~ of the total h eat transferred. This validates Assumption No.4 above.

CALCULATION S

A x ial Temperature Distribution in the Combustion Gas, Fire Tubes, and C oo ling Water. The heat-temperature c hang e relationship for the fluids is g i ven by the e qua tion

( l )

where Q is the h eat transferred per hour, C is the specific heat (at constant pressure for gas ) in Btu/lb, oF. w is the flow rate in lb/hr and T 2 and T 1 a r e the fina l and initia l fluid t emperatures. The heat transferred across a tub e wall b y flowing fluids is expressed as

L'.Tm

Q = l

:6 -u

( 2)

5 1

Ul N

300

280 l 260

1-'-< 0

~ 240 Q) .... ;:! ..., ~ 220 Q)

I P.. 1-'-<

s

~ 200~ Q) .... ;:! ..., g Q)

~ 180 P..

r s Q)

1--<

P' 0 160 0 u

-~- 140

120 _.. ,,. 100

80

v

3600

3200 ~ I Cas temperat ure

Water tempe ra ture

G as phase change

0 u

1 2 3 4 5 6 7 8 9

Dista nce Aft of Sta tion 0, ft

FIG . 37. Axia l Temperature Distribution, Moray Test He at Exchanger.

10 11 12 13

,..

z ~ < ~ M 1:J r:J)

~ M 1:J 0 ~ ~

00 --D --D 00

-., -n-1

=

Ul w

, ..

1-L. 0

0 0 '<!' N

,

1-L. 1-L. lV II // ///// I I I I ///// 1 I

0 0 0 0\

I

0 l.f) \0

'------.~--JI

I I I 90oor I I I

2400- 2500°f

I I

FIG. 38. Temperature Distribution in Tube Sheet Section, Moray Test Heat Excha nger.

lr

1-L.

z ;t> < ~ M 1J U'l

~ M 1J 0 ~ f-j

00 --D --D 00

NAVWEPS REPORT 8998 UNCLASSIPt!tm= t,Tm is the log mean temperature difference between the initial and final t emperature difference. ~ ( l /U) is the thermal resistance in o F hr /Btu and is equal to

1 1 1 = --- + ----- + ----

u 2nki ( 3)

w h e r e Di a nd D 0 are the inside and outside diamete rs of the tube, p_ is the tub e length, hi and h 0 are the inside and outside film coefficients, and k is the the rmal conductivity.

Since the specific h eat-film coefficient and the rmal conductivity v ary w ith temperature, the tube wa s split into small s egments across w hich these variables we re assumed to be constant and e qual to th e mean valu e. An ite rative process was r e quired to d e t e rmine the temp e rature distribution that satisfied all conditions specified b y Eq. l and 2. A shortene d ca l c ulation follows for the temperature c hange b etween Stations 0 and l. S tation 0 is the ba ck face of the main tube sheet, w hile Station 1 is 3.0 inches dow nstr eam from Station 0. The initial segment length was 3.0 inches . As the temperature drop along these s egments decreased, the l ength was increased to 6. 0 inches and finally 1. 0 foot.

The film coeffi c i ent h, as pres e nted by Brown and Marco, (R e f. 3) reads

k (DVp)o. s (Cpf-1. )0.4 h = 0.023- -- - -

D fl. k

Fo r noncircular sections, Dis the equi val ent diameter and is e qua l to four times the cross sectional a r ea divided by the p e rimete r through w hich h eat is transfer r ed . The values of h for the combustion gas and cooling water are plotted in Fig. 39 and 40 against film t empe rature. These values are based on fl.; k, a nd Cp cal c ulated for the Moray heat exchanger. The film te m p erature is the mean b etween the bulk, or fluid, t emperatur e and tha t of the b ounding surfac e .

STATION 0

The first step in th e ite r a tive process is to es timat e a va lue for all va riables 1n Eq. 3. F or the 79 tub es , these var iables read

1 l l l a

= = = a 0 . 000945--

uga s nD iP.hi A.h. I l

79 X 0.25 X 0.047 X 1140 Btu

.... .., .. ~ m CJ,,

Vl Vl

'"' ...c: N

.:::: r..... 0 ..... ::l '-' o:l

£ '-' = .~ u ~ ...... Q)

0 u _§ I-'.

2000

1800

1600

1400

1200

1000

800

600

400 400 600 800 1000 1200 1" .. 00 1600 1800 2000 2200 2400

Tempe ra ture, ° F

FIG. 39. Film C oe ffici ent h; Diese l Oil-GOX Combusti on Pwducts a t ::::::3,000 psia .

2600 2800 3000

z ~ < ~ M 1:J (/)

!::0 M 1:J 0 !::0 J--3 00 ...0 ...0 00

NAVWE PS REPORT 8998 u N ClASS I ftftrTIAh l l l l

U water 79 X 0 . 25 X 0 . 0654 X 4490

l l n(D 0 / Di) 0.33 hr °F = ~ ---------- a 0 . 000243 --

Utube 79 X 6. 28 X 0. 25 X ll Btu

and l hr°F

L a 0 . 00136--u Btu

where ~ means "is estimated to be equal to." The t emperature drops across the gas film, tube wall, and water f ilm are

l

Ugas 0. 000945 ~ ( 29 50 - 70) ~ 2000°F t::,Tgas = t::,Ttotal

l 0 . 00 136

u

t::,Ttube ~ 5 14oF and

The average temperature across the gas or liquid fi l m is used in evaluati ng the film properties. The gas film t emperature 1s

the wate r film temperature is

and the average tube temperature 1s

Using these temperatures and Fig . 39 - 41, the values of the v ariables in Eq. 3 are as follow s: gas f ilm coefficient, hg = 780 Btu / °F ft 2 hr; water f ilm coefficient, h w = 4420 Btu/ oF ft 2 hr; and the average ther mal conductivity of the tube, 1 1 . 0 Btu ft / ft2 hr °F. Nea r the tube inl et, Brown a nd Ma r co give a correcti on factor of l . 5 1 for the gas f i lm coef fic i ent at thi s station. Therefo r e, hg = 780 X l. 51 ~ 1 200 Btu / °F ft2 hr . If these va lues were far from the original estimate , they would be used to re - eval uate Eq. 3.

The next step is to estimate the temperature of the gas, water , gas film, water film, and tube at Station l. Using these guesses, the

56 u N cLASs lf~r&TIA£


38

N 37 I 0

X

..2 N 36 ~

io... ? :,· '-' >0

-,.,;:; 35 ~ .S u

;.:; "" <lJ 0 34 u

_§ U-

33

32 210 220 230 240 250 260 270 280 290

F ilm Temper.; ture, OF

FIG. 40. F ilm Coefficient of Cooling Water for Test Heat Excha nger.

17 U-

.... 16

N 15 ~

4::! 14

:::1

"' co

.Y 13

:.-. '-'

.::; 12

<1 11 -iJ c 0 10 u

200 400 600 800 1000 1200 1400 1600 1800 2000

Tempera ture, Of

FIG. 41. Therma l Conductivit y k; 302 Sta inl ess St eel Versus Tempera ture .

57

NA VWEPS REPORT 8998 UN GLASS I RfiOwl'~ variables in Eq. 1, 2, and 3 are determined and these equations evaluated. The results of this step will give new values of the temperatures at Station l. Using these new temperatures, the process is repeated until no further increase in accuracy is justified.

Assume at Station 1 that T gas ~ 2543°F, and THzO ~ 9 6°F. The shortness factor is now 1 . 14. Therefore,

1

and

hg ~ 725 X 1.14 ~ 825 3U/hr £t2

oF

a 0 . 00130, 1

a ---- 0.000219,

1 L a 0. 001773

u

1

Utube

a 0.000254,

whe re the units have been omitted for convenience . Using these values , the temperatur es across the films and the tubes are

0.00130 6Tgas = 2447 X = 1 780 °F

0 . 001773

and

The film and tube temperatures are

and

Using the se temperatures and Fig. 39 - 41, the film coefficients are hg = 725 X 1.1 4 ~ 8 25 and h w ~ 3565, and the tube thermal conductivity is k = 10.5. Again, if these values were different from the original estimate, the iterative process would b e used to re-evaluate the va riables m Eq. 3.

The average value of L: ( 1 /U) between Stations 0 and 1 is

1 0.00177 + 0 . 00 1 36 I--= =o.ool56

U a vg 2 ('

c~ . s-· H=fY¢~

NA VWE PS R EPORT 8998

and the log mean temperature difference is

6T0 - 6T 1 2880° - 244 r

---- = = 266 0 ° 2880°

ln ---

Using Eq. 2, the heat transferred across the tube between S tatio n s 0 and 1 is

6Tm 26 60 Btu Q= ~ ~ 1' 7 00 , 000

1 0.00 1 563 h r I

Uavg

and the changes in temperature of the gas and w ater are

Q l' 700 , 000 = -- ~ ---------- ~ 407°F 6Tgas

wcp 2 . 26 X 3600 X 0 . 5 14

1 ' 700,0 0 0 6TH2o = = 26°F

18 X 3600X l

The new t emp e ratures at Station 1 are

T gas~ 2950 ° - 407 ° = 2543 °F

TH20 = 70 ° + 26° = 96oF

TUBE SH EE T TEMPERATURE

Because of the c l ose spacing of the tubes and thei r symmetr y , the tube sheet whic h contains them can be broken up into many small seg ments. These segments are bounded eithe r by a portion of a t u b e or a plane ac ro ss w hich no heat flows, dT / dX = 0. These small segments can b e ana l yze d as extended surfaces protruding from the d iluent water . For steady - state conditi ons to exist, all heat transferred to the ex tend e d surface must pass i nto the di luent water. T h e wate r r ecei ves heat e i the r at the t ube sheet surface, o r through the tubes, w hic h ac t as an extended surface protruding from the tube sheet .

The h eat transfer and temperature dist r ibution equations for ex tend e d surfaces read

59

NA VWEPS REPOR T 8998 ~lASSJaEO~rAL

h cosh m ( L - X) + - sinh m ( L - X)

T - Ta mk --- = ( 4 ) T 5 - Ta h

coshmL + -- sinhmL mk

h sinhmL + -- coshmL

mk q = '\/PhAk (T 5 - Ta) ----------

h coshmL + -- sinhmL

mk

(5)

and for finit e extended surfaces

whe r e

T- Ta coshm (L- X) --- = ( 6) T 5 -Ta coshmL

q = '\/ PhAk ( T 5

- Ta) tanh mL fo r in s ulate d e nds

P = extended - surface heating perimeter

h = film coefficient at side - heating surface

h = film coeffic i ent on end of extended surface

k = thermal conductivity of e x tended- surface material

A= cross - sectional a r ea of extended surface

T 5 = temperatures at base of extended surface

T a = temperature of fluid a round extended surface

m2 = hP/kA

( 7)

The gas-film coefficient, h , is the fi l m coefficient inside the tubes and is the same as in the section abo ve. The water -film coefficient is computed from r e l ations between h and the flow rate normal to banks of tubes. Thi s r e lationship reads

(v )o.6 m ax

h = 370 ( l + 0. 0076 t£) ----(Do) 0.4

(8)

•

lf4GWSIFIED NA VWEPS REPORT 8998

where

t f = film t emp e rature

V max = veloc ity based on c r oss -s ectional ar ea, ft/ sec

D = outside diamet e r of tub e s, in. 0

h = 21 6 0 + 1 4. 9 t f Btu / ft 2 oF h r

for this physica l configuration and diluent flow rate . The film coefficient fo r wate r against the surface of the tube sheets could only b e es timated . It was found, however, that a change of 150 percent in this coefficient resulte d in a temperature change of only a bout 1 00 °F at the 11hot spot . 11 Therefore, the t empe ratur e reporte d at the 11hot spot 11 is conside r ed to be a maxi mum. The film coefficient on the front or end of the extende d su r face also was es timated . Calculations again show that a l arge change in this coefficient has small effect on the highes t temperature of the surface.

For computatio n, P = the sum of the heat-transferring perimeters of the tubes . A= the total frontal surface area of tube sheet. The perimeter and cross - sectional area of the e x tended s urfac e w ill be

p

Pl= N

whe r e N = number of fins and

hP 1 m2 = rA 1

E quation 7 now reads

and

hP

N =

rA

N

=

A A=

N

hP

rA

____ q ____ = N0 P1Athk = N ~ = 0 PAhk ( T s - T a )tanh mL ~ --;:; --;:; h.K

(9)

which provides a satisfactory evaluation of heat tran sfer and tempera tu r e distribution .

FI·E 61

NAVWEPS REPORT 8998 UNCLASSIR~ HEAT FLOWING INTO DILUENT WATER THROUGH TUBES ACTING AS EXTENDED SURFACES

The variables in Eq. 9 are evaluated as

3. 14 1 A= 79(0 . 25 2

- 0.18 2) -- X -= 0.0129 ft 2

4 144

0.25X3 . 14X79 p = ------- = 5.16 ft

12

0.14 L = -- = 0. 0117 ft,

12 k = 13

h = 6200 Btu/ft2 °F hr (tf = 300°)

6200 X 5. 1 6 m 2 = ----- = 190,000, m = 435

13 X 0.0129

mL = 435 X 0.0117 = 5 . 1, tanh 5.1 = 1

and the results from Eq . 9 are

q 1

= ,_) 6200 X 13 X 5.1 6 X 0 . 01 29 { T5

- 70) X 1

q1

= 73T5

- 5100

HEAT TRANSFERRED TO DILUENT THROUGH FACE OF TUBE SHEET (q 2 )

The variable s in Eq. 2 are evaluated as

3. 14 79 A= 8 . 30 in. - 0.25 2 X-- X--= 0.0306 ft 2

4 144

and if h 5 = 2200, then q2

= 6 1 T5

- 4280; or if h5

= 5000, then q

2 = 153T - 10,700 where

1 1 I-=- and

u hA

62 UN CLASS~

•

..

IINOfAS-Sf FlED NAVWEPS REPORT 8998

HEAT TRANSFERRED FROM GAS TO EXTENDED SURFACE

and

The va riables in Eq. 9 are evaluated as

3 . 14 3 . 14 79 A= 3.25

2 X --- 0 .1 8

2 X -- X --= 0 . 0437 ft

2

4 4 144

0. 18 X 3. 14 X 79 p = ------- = 3 . 72ft

1 2

0 . 25 L = -- = 0 . 0208 ft,

1 2

h = 1200

h = 400 ( estimate)

l 200X3.72 rn2 = ----- = 68 10,

15 X 0.0437

hl 400

k = 15

m = 82. 5

= =0 . 323=1.72 mk 82.5 X 1 5

t anhm L = tanh (0.0208 X 82.5) = 0.94

q = 0 3 . 72 X 1200 X 0.0437 ( 3000 - T )0. 94 = 1 52,000 - 50.4T 3 s s

The heat transferred from the gas is equal to the heat gaine d by the water, i .e . , q 3 = q 1 + q 2 . L: for

therefore,

and

h = 2000 s

l 85T 5 = 1 66, 000 a nd

q = 152, 000 - 45 ,3 00 = l 0 6, 700 Btu /hr 3

l TL = 300 0 - (30 00 - 900 )

3 . 2

63

NA VWEPS REPORT 8998 u N Gl:ASSiftEFft~IAb

For h5

= 5000,

and

therefore,

q 3

= 124,000 Btu/hr

For the main tube sheet,

and

126,000 > q > 111,000

The heat flow through each fire tube between the tube sheets may be written as

liT Btu q = = 160,000

4 1 hr

I-u

and the total heat flow is as follows:

q = q3

+ q4

= 284,000 Btu/hr tota l

Thus, the change in temperature of diluent wate r is

Q 284,000 = --------= 61°F

wCp 1 . 29 X 3 600 X 1. 0

CLAS tFtBJriAL

'

..

•

NAVWE PS REPORT 8998

Appendix B

GAS TEMPERATURE ANALYSIS, SINGLE-TUBE HEAT EXCHAN GER FOR MOR AY CO MBUSTION TESTS

A two - inch, extra - strong copper pip e is to be used for the heattran sfe r tub e in th e modified heat exchanger . This s i ze gives the max imum s urface a r ea cons istent with st r ength a nd compatibility with the existing ca sings. The l e ngth of the tub e w ill b e appro x imately 1 2 feet.

The basic heat transfer equati on r eads

6T Q = UA6T =

.Z::R ( 1 0)

w h e r e the .Z:: R is the sum of a ll r es ista n ce t o h eat transfe r and Q i s th e he at transferred per unit time. Analysis shows that a ll r es istanc es to heat transfer other than the gas film are sma ll (less than 5 percent) compared to th e gas film resistance .

Therefore, the b as i c heat transfer equ a tion can b e a pprox ima t ed w ith satisfactory accuracy b y

( 11 )

w her e he is the film coeffic i ent, A the tube inside area, and 6 T the gas bulk temperature minus wall t emp e r a tur e (tb - t w ).

The equation for he at transferred per unit time p e r unit l e n g th r eads

where Dis the tub e insid e d i ameter.

( l 2)

The t empe rature drop in the gas caused by a given heat-transfer rate may be expressed as

where in is the mass flow rate, CP the gas specific heat at constant pre ssure, and 6tb the change in gas bulk temperature.

( 1 3)

65

NAVWE PS R EPORT 8998

Combining E q. 12 and 13, the equation for instantaneous change of temperatur e with length reads

dq = rnCP

d£

rnCP

dt

dq = fficpdt

dq Q=-

d£

= he nD6 T = he nD( tb d£

dtb = Q= nDhe(tb - tw )

d£

- t w )

Kreith (Ref. 4) gi ve s the gas -film coefficient equation as

w here G is the mass flow rate per unit cross - s ecti onal area, lbmass / hr ft 2 , and i s equal to

4 m

( 14)

(15)

( l 6)

(All physical properties are eval uated at the average gas bulk tempera ture . ) For a gas cooling , n = 0 . 15; and for constant wall temperature, C = 0. 020. Ins erting Eq. 15 and 1 6 into 14, this equation reads

4:ffi -o.2 = CP -- (0.020) R e

nD2

t0. 15 b -2/3 -- P r nD( tb

t w

or, after di viding through by rnC P,

dtb 4 - =- ( 0.020 )(R f 0

•2

e d£ D

t 0.15

_ b_ ( p ) - 2/3 ( t - t ) r b w

t w ( l 7a)

Assuming that the gas properties are the same as steam, and noting that the factors t~· 15 / t w and (Prr213 change ve ry little with a large change in average bulk temperature, Eq. l 7a can be written

dtb = k (tb - t ) w ( l 7b)

d£

66 u LA IAL

i

..

•

•

UHGhASSIEIED. N A VWEPS REPORT 8998

w her e an es timated average bulk gas t emperature is used to evaluate the gas properties. The kin this equation is a function of rn and must be r e - evalua t e d for each mass flow rate. I ntegrating Eq. 1 7a and arranging t e rms gives

tb = (t b - t )eke + t 0 w w

(1 8 )

Figure 42 is a plot of Eq. 18 w ith k evaluated for flow rates of 0.116 lb/ sec (minimum design) and 2. 26 lb / sec (maximum design), and for a mid - flow rate of 0. 38 lb / sec. A conse r va tive t w of 200°F was used . This temperature i s somewhat high, but the final gas temperat u re is fairly insensitive to change in t w.

Figure 42 is only valid down to the gas temp erature at which condensation starts. At 1, 000 ps i, this temperature i s a bout 550 °F .

Figure 42 can be used to arrive at an approximate solution of gas temperature at the combus tion chambe r outlet; i . e. , if the measured exhaust gas temperature at the nozzle is 1400°F and the m ass flow rate i s 2. 26 lb/ sec. The combustion-chamber gas temperature is approx imated b y entering the chart at 1400° (1 ), moving to ( 2) for the mass flow r ate of 2.2 6 lb/ sec, and reading the tub e l ength on the horizontal scal e ( 3), then going upstream 12 feet (heat- exchanger length) from this point (4 ) and r eading up to the 2. 26 lb/ sec line ( 5). The temperature corresponding to this point ( 6 ) is the combustion chamber gas temper a ture, in this case 2200 °F .

67

NAVWEPS REPORT 8998 UN C LAS&lfiJill

N I 0 ..... X 20

"'"' 0

OJ~

:l ..., ~ 18 OJ 0.. s OJ

E-<

"' "' 16 ()

14

12

10

0

1

2.26

I I I I -------I I

Total m ass flow in lb/ sec

0.116

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

Tube Length, ft

FIG. 42. Tempera ture Drop in Tube for Modified Moray Test Heat Exchanger,

Tube Length 12 ft .

•

..

UtH)I:A&s IF IE D NA VWE PS REPOR T 8998

Appendix C

ADIABATIC FLAME TEMPERATURES FOR JP-4 - GASEOUS OXYGEN - DILUENT WATER

AT 68 ATMOSPHERES

To facilitate design of parts and eval uation of test results , gas compositions, and adiabatic flame temperatures for va rious va lues of oxidizer-to-fuel (0 / F) and diluent - to-fuel (Dil / F) ratios of J P -4 -gaseous oxygen - diluent water at 68 atmospheres ( 1, 000 ps i) were computed.

A computational procedure, using equilibrium constants estimated by a method described in Ref. 5, was devised to yie l d these results and was programmed in SOS language for the IBM 7090 computer .

After the computation was about two - thirds completed , d i ff i culties arose with the convergence procedures used and the computations were completed using Program No. 2272 (Ref. 6 ) on the IBM 7090 computer.

Figure 43 gives the adiabatic flame temperatures ob tained as functions of 0/F and Dil / F ratios at 68 atmospheres pressu r e .

lfi'ED 69

NAVWEPS REPORT 8998 UN GbASStft£1

~ 0

0)~

.... ;:l +>

"' .... 0)

0. s 0)

!-<

6500.--------------r--------------.-------------~--------------.

4000

3500

3000

2500

500L-------------~-------------L------------~------------~

1.0 2.0 3.0 4.0

0/F Ratio

FIG. 43. Va riations of Ad iabatic Fla me Temperature With 0/F and Dil/F Ratios;

JP-4-GOX-H20 , P = 68 Atmospheres.

5.0

..

I •

•

•


REFERENCES

l. U. S. Naval Air Rocket Test Station. Investigation of Methods for Varying Thrust in Rocket Engines, by F . R. Hickerson. Lake Denmark, Dover, N. J., NAR TS, April 195 6 . (NAR TS 88, TEDAR TS-SI-5309.) CONFIDENTIAL.

2. Rutkowski, E. V . "Recent Advances in Variable Thrust Propulsion, 11

in Bulletin of the S econd Meeting of the Joint Army-Navy - Air Force Liquid Propellant Group, San Diego, Calif., November 19 60. Pp. 589 - 608 .

3. Brown, Aubrey I. , and Salvatore M. Marco. Introduction to H eat Transfer, 3rd ed. N ew York, McGraw -Hill, 1 958. Pp. 141-42.

4. Kreith, Frank. Principles of H e at Transfer. Scranton, International T extbook Co., 1958 . P. 347.

5. Smith, J. M. Introduction to Chemical Engineering Thermodynamics. N ew York, McGraw -Hill, 1949. Pp. 339 - 342.

6. U. S. Naval Ordnance T e st Station. The Theoretical Computation of Equilibrium Thermodynamic Properties and Performance Charac teristics of Propellant Systems, by H. N . Brown, N . M. Williams, and D. R. Cruise. China Lake, Calif., NOTS , 8 June 19 60. (NA VWEPS 7043, NOTS 2434. )

71

NAVWEPS REPORT 8998

INITIAL DISTRIBUTION

8 Chief, Bureau of Naval Weapons DLI- 31 ( 2) RR (1) RRRE (1) RU (1) RUTO ( 1) RUT0-3 (1) RUTO- 32 (1)

3 Special Projects Office Sp 20 (1) Sp 22 (1) Sp 27 (1)

2 Chief of Naval Material Manager, ASW Office (1)

1 Chief, Bureau of Ships ( 603) 1 Chief of Naval Operations 2 Chief of Naval Research

Cod e 104 (1) Code 466 (1)

1 Antisubmarine Warfare Forc e, Atlantic Fleet 1 Antisubmarine Warfare Forc e, Pacific 1 Atlantic Fleet ASW Tactical School, Norfolk (Technical Library) 1 David W. Taylor Model Basin l First Fleet 1 Fleet Anti-Submarine Warfare S chool, San Diego l Long Beach Naval Shipyard l Naval Advanced Undersea Weapons S chool, Key West l Naval Air Development C enter , Johnsville 1 Naval Aircraft Torpedo Unit, Naval Air Station, Quonset Point 1 Naval Civil Engineering Laboratory , Port Hueneme 1 Naval Missile Center, Point Mugu 1 Naval Ordnance Laboratory, Corona 2 Naval Ordnance Laboratory, White Oak

Technical Library, Dr. S. J. Raff ( 1) l Naval Postgraduate School, Monterey (Libr a r y, T echnical R e ports

Section) 2 Naval Research Laboratory

Code 5550 ( 1)

L

l Naval Scientific and Technical Intelligence Center, Naval Observatory 2 Naval Torpedo Station, Keyport

Quality Evaluation Laboratory, T echnical Library ( l) Director, Research and Engineering ( l)

•

•

UNCLASSIFIED

Security Classification

DOCUMENT CONTROL DATA· R&D (Security clttssilication of titl e , body of abstract and indexinjl annotation mu s t be entered when the overall report is c lassified)

t 1 . QqiGINA TIN G ACTI V IT Y (Co rporate author) UNGI 2 a9£~tJr~~~tlriTION u. s. Naval Ordnanc e Test Station Ml W!l'11 •• ••

China L ake , Calif. 93557 ~ ~ G'AoW' 'tllllllr • I I ... I~

t 4 3 . REPORT TITLE

COMBUSTION APPARATUS FOR AN UNDERWATER THERMAL PROPULSION SYSTEM (U)

4 - DESCRIPTI VE NOTES ( T ype of repo rt and inclusive dates)

Developmental r eport 5 - AUTHOR (SJ (Last name , first name , initial)

Reisman, C. A.; Caraher, J. M.; Jackley, D.N.

6 . REPORT DATE 7a . T-OTAL NO . OF PAGES ?b . NO . OF REFS

February 19 66 72 6

ea . CONTRACT OR GRANT NO . 98. ORIGINATOR •s REPORT NUMBER(SJ

Bureau of Naval Weapons Task NO TS TP 3969

b . PRoJEcT No.Assignment No . RUT0-2D-000 /21 6-l/S44 7

c . 9b. OTHER REPORT NO(S) (Any other numbers that may be assigned thi s report)

d . NAVWEPS REPORT 8998

1 o. AVAILABILITY / LIMITATION NOTICES

Qualified requesters may obtai n copi e s of this r eport from DDC.

11 . SUPPLEMENTARY NOTES 12 . SPONSORING MILITARY ACTIVITY

• D epartment of the Navy (Bureau of Naval W e apons )

13 . ABSTRACT A combustion apparatus that provides a var iab l e flow rate of 2500 ° F gas to the boiler of a closed - cycle steam power plant wa s des igned a nd developed for use i n an underwater thermal propulsion system. The prope llants are high-pr essure gaseous oxygen and liqui d hydrocarbon fue l in stoichiometric ratio w ith recirculated diluent water to contr ol the gas temperature. The combustion system consists of an i gniter chamb e r, a main combustion chamber, and a flow-control devi ce w hich maintains fu e l, oxidi zer , and d iluent-wat e r ratios over the operating range from full power to l/25 full power . A va riable-area nozzle main-~ains any desired combustion - chamber pressure b e twe en 100 and 3, 000 psi over the entir e flow- rate range . The apparatus is capable of multiple restarts and should yield operating periods of at l ea st 100 hours w ithout maintenanc e. (UNCLASSIFIED)

DO 1473 FORM 1 JAN 6 4 0101-807-6800 UNCLASSIFIED


14-

UNCLASSIFIED Security Classification

KE Y WORDS

Underwater propuls i on The r mal propulsion system Clo sed -cycle steam system Variable - flow nozzle Electric s p ark ignition Heated- surface ignition MO RA Y

LINK A

ROLE

LINK 8 LINK C

WT R OLE WT ROLE WT

INSTRUCTIONS

\, ORIG I NATING ACTIVITY: Enter the name and add ress of the contr actor, subcontractor, gr antee, Department o f Defense activity or other organization (co rporate autho r) issuing the report.

2a. REPORT SECUFdTY CLASSIFICATION: Ente r the overall security c las sification of the report. Indicate whether "Restricted Data" is included. Marking is to be in accordance with approp riate security regula t ion s .

2b. GROUP: Automati c downgrading i s specif ied in DoD Direc ti ve 5200. 10 and Armed F o rces Industri al Manual. Enter t he group numb e r. Als o, when a pplicable, show that op tio na l markings h ave been used for Group 3 and Group 4 as authorized.

3. REPORT TITLE: Enter the compl ete repo rt title in all capital lett e rs. Titles in all c ases should be unclassified. If a meaningful title cannot be se l ected wit ho ut classification, show title class ification in all capitals in parenthesis immediate ly following the title.

4. DESCRIPTIVE NOTES: If appr opri a t e, e nter the type of report, e. g., int erim, pro gress, s umm ary, annual, or final. Give the inc l usive dates when a specific reporting period i s covered.

5. AUTHOR(S): Enter the name(s) o f author{s) as shown on or in the report. Enter last name, fir st name, middle initial. If military, s how rank and branch of service. The name of the principal author is a n ahsolute minimum requi reme nt.

6. REPORT DATE.: Enter the date o f the report as day, month, yea r; or mo nth, yea r. If more than one date appears o n the repo rt, use date of publication.

7a. TOTAL NUMBER OF PAGES: The total page count s hould follow nonnal pag ination procedures, i.e. , enter the number of pages containing informat ion.

7b. NUMBER OF REFERENCES: Enter the total numb e r of references c it ed in the repo rt.

Sa. CONTRACT O R GRANT NUMBER: If appr opriate , enter the app l icable numb er of the contra c t or gra nt under which the report was written.

Sb, &:, & 8d. PROJECT NUMBER: Enter the appropriate military department identification, s u ch as project number, subproject numb er, system numbers, task numbe r, e tc.

9a. ORIGINATOR ' S REPORT NUMBER(S): Enter the offic i al report number by which the document will be identified and co ntrolled by th e originating activity. This numb er must be unique to this report.

CJb. OTHER REPORT NUMBER(S): If the report has been ass igned a ny o ther repo rt numbers (either by th e oriainator or by th e spo nsqr), a l so enter this number(s).

10. AVAILABILITY/ LIMITATION NOTICES: E nter any l imitati ons on further disseminatio n of the report , other than those

imposed by security classification, using standa rd statement s such as:

(1) " Qua lif ied requesters may obt ain copies of this repo rt fr om DDC,

(2) "Fo reign announceme nt a nd dissemination o f this report by DDC is not autho rized"

(3) "U. S. Government agencies may obtain copies of th is report directly from DDC. Other qualified DDC users shal l reque s t t hro ugh

( 4) "U. S. military agencies may o btain copies of this repo rt directly from DDC Other qualified u sers shall request through

(5) "All distribution of this r eport is co ntroll ed. Qualified DDC users shall request thoug h

If the repo rt has been furnish e d to the Office of Technical S e rvices, Department of Commerce, for sa le to the public, indicate thi s fact and enter th e p rice, if known.

11. SUPPLEMENTARY NOTES: U se for additional explan atory notes.

12. SPONSORING MILITARY ACTIVITY: Enter the name o f t h e departmental project office or laboratory sponso ring (paying for) the researc h and d evelopment. Include address.

13. ABSTRACT: E nter an abst ract giving a brief and fac tual summary of the document indicative o f the repo rt , even though it may also appea r elsewhere in the body of the technical report. If additional space i s required, a cont inuation sheet s hall be attached.

It is highly desirable that th e abstract of classi fi ed reports be un c lassi fied. Each paragraph o f the a bstract shall e nd with an ind ica ti on o f the mi l i tary security classi fi cat io n o f the in fo rmati on in the paragraph , repres e nted as (TS). (S), (C). or (U) .

Th e re is no limitation o n the length of the abstract. Howeve r, the suggested length is from 150 t 0 225 wo rds.

14 . KEY WORDS: Key words are technically meaningful terms or s hort ph rases that c haracte riz e a report and may be used as index entries for cata l oging the report. Key words must be se l ec ted so that no security c las sification is req uire d. Identi fiers, s uc h as equipment mode l designation, trade name, military proj ect code name, geographi c location, may be used as key w o rds but will be followed by an indication of technical context. The assignment of link s, roles, and weights is optiona l.

UNCLASSIFIED


•

l Naval Underwater Ordnance Station, N ewport l Naval Underwater W eapons Systems Engineering C enter, Newport l Naval War College, N ewport l Naval Weapons Laboratory, Dahlgren 2 Naval W e apons Services Office (Code DM) l Navy Electronics Laboratory, San Diego 2 Navy Marine Engineering Laboratory, Annapolis

Code 840 ( l) l Navy Mine D efense Laboratory, Panama City l Navy Underwater Sound Laboratory, Fort Trumbull l Norfolk Naval Shipy ard (Underwater Explosion R e search Division) l Puget Sound Naval Shipyard l Submarine Development Group 2 2 Frankford Arsenal

T e chnical Library ( l) 20 D efense Documentation C e nter ( TISIA-l)

l A e rojet-General Corporation, Azusa, Calif., via BWR l Applied Physics Laborator y , University of Washington, S e attle l Clevite Ordnance, Cleveland l Davidson Laboratory , Stevens Institute of T e chnology, Hoboken, N.J. l D efense R e search Laborator y , Univ ersity of T exas, Austin l Electric Boat Division, G eneral Dynamics Corporation, Groton, Conn.

(D. D. Walden) l G e orgia Institute of T e chnolo gy, Atlanta (Chief of the Physical

S c iences Division) 1 Lincoln Laborator y , MIT, L exing ton l Ordnance R e search Laboratory, Pennyslvania State Unive rsity,

State College 1 The Rand Corporation, Santa Monica, Calif. (Ae ro-Astronautics

D e partment) l W e stinghouse R e search Laboratories, Pittsburgh (Arthur N e lkin)

COMBUSTION APPARATUS FOR AN UNDERWATER THERMAL … · 2018-12-06 · The combustion system consists...

Documents

Transcript of COMBUSTION APPARATUS FOR AN UNDERWATER THERMAL … · 2018-12-06 · The combustion system consists...