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Technical College of BasrahRefrigeration and Air Conditioning Dept.

Q1// the velocity of steam at inlet to simple impulse turbine is 1000 m/s and thenozzle single is 20 o. The blade speed is 400 m/s and the blades are symmetrical.Determine the blade angle, tangential force, diagrame po er, a!ial thrust, and thediagram efficiency for frictionless blades."f the relative velocity at e!it is reduced by friction to #0$ of that at inlet, thenrecalculates the diagram po er, a!ial thrust, and the diagram efficiency. Ta%emass flo rate 1 %g/s . Answer (32.5 o 1!"5.2# $ %2".2# &' ! $ 5.25 )3 3."%3 &' "#. * $ #".#)+

Q2// a stage of a turbine ith &arson's blades of (0$ reaction degree delivers thesteam from the fi!ed blade at )0 m/s. The moving blade e!it angle is 20 o and theinlet a!ial velocity f i of the steam is */4 of the blade velocity. "f the steam issupplied to the stage at a rate of )000 %g/hr, determine+

1. The diagram po er.2. The diagram efficiency.*. The total enthalpy drop of steam in the stage.

Answer, (131%3.5 ' - # .#) - 525# & /&g+

Q3// a single ro impulse turbine receive * %g/s of steam ith velocity 42( m/s .The blade speed ratio is 0.4 and the output po er is 1 1.(# %-. "f the frictionallosses in the moving blade amount to 14.)2 %-, determine the diagramefficiency and the blade velocity coefficient. The nozzles angle is 1 o .Answer, ("3.32)- !.*2#+

Q%//a simple impulse turbine De aval turbine is supplied ith steam at 1( bar,400 o 3superheat. The steam e!pands in the nozzles, hich have an efficiency of )0$, to pressure of 1bar. ssuming the nozzle angle is 20 o, blade velocitycoefficient is 0.#, and symmetrical blades5 determine for ideally ma!imum bladeefficiency condition+1.The blade speed. 2. The blade angle. *.The po er output for hr kg m /)000= .4.6et the summation of nozzle losses, useful output or%, blade frictional losses,and leaving %inetic energy5 hich must be e7ual to the isentropic enthalpy drop.answ(%*3.*!2 /s- 3".!5 o-1!*#.#5&'-no00le losses,"1.%" & /&g-energ

o tp t,%3*.1 & /&g -friction losses,"#.1 & /&g- resid al &inetic energ ,%".2%& /&g+

ct, 6ower 6lant Technologpter, tea T r4inest rer, .8 .9aisal//:. c B. c :ech .;ng

Class, % th Date, 5/%/2!!#

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Q5// The rotational3speed of an impulse turbine heel is *000 r.p.m. The nozzlesare inclined at 20 o and their efficiency is 0.#). The isentropic heat drop for thestage is 1() %8/%g. "f the blade speed ratio is 0.4, the blade speed coefficient is0.#2, and the blade efficiency is 0. . 9ind for steam flo rate of 1( %g/s+1. The mean blade ring diameter.2. The po er developed by the stage.Answer (1.355 1"13.2 &' +.

Q"// the nozzles of the impulse stage of turbine receive steam at 1( bar, *00 o

and discharge it at 10 bar. The nozzle efficiency is )( $ and the nozzle angle is20o. The blade speed is that re7uired for ma!imum po er and the inlet angle ofthe blades is that re7uired for entry of steam ithout shoc% .the blade e!it angleis ( o less than the inlet angle. The blade velocity coefficient is 0.). alculate forsteam flo rate 1*(0 %g/hr+1. The diagram po er. 2. The diagram efficiency.Answer (3!.3 &' ".3 ) +

Q#// the steam from the nozzle of single heel impulse turbine discharges ithvelocity of 00 m/s at angle of 20 o . The blade heel rotates at *000 rev/minand the mean blade radius is ()0mm. the a!ial velocity of steam at e!it from the

blade e f is 1 4 m/s and the blades are symmetrical, calculate+1. The blades angles.2. The diagram po er.*. The diagram efficiency .4. The blade velocity coefficient.Answer (2 o 12".3 &' #!) !.#**+

Q /in a reaction turbine stage, the fi!ed and moving frictionless blades are of thesame shape ith inlet and outlet angles of *( o and 20 o respectively. The mean

blade heel diameter is 0.2*)m and the rotational speed is *000 r.p.m . Thesteam is supplied to the stage at 4 %g/s. alculate+1. The output absolute velocity and its angle.2. The output po er and the diagram efficiency.*. The total enthalpy drop in the stage in %8/%g.4. The ma!imum diagram efficiency that can be obtained and the value of bladespeed ratio at hich it occurs.

Q* / ompare bet een impulse and impulse3reaction turbines.

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Q1!/ for &arson turbine of (0$ reaction degree ,derive an e!pression for bladeefficiency sho ing the optimum operation of blade speed ratio b/a i and thecorresponding ma!imum efficiency po er.

Answer,i

ii

i

i

ib

a

b

a

b

a

b

a

b

cos/2/1

cos2/2

2 +

= -here ia

b is the blade speed ratio

:y ma%ing0

/

/=

i

b

a

bd

d

e find ioptimumi

a

b cos= 5 ma!

i

ib

2

2

cos1

cos2

+= 5 po er; 2bm

The velocity diagram ill be+

Q11// for De aval turbine of symmetrical and frictionless blades degree ,derivean e!pression for blade efficiency sho ing the optimum operation of blade speedratio b/a i and the corresponding ma!imum efficiency po er.

Answer, /cos4i

i

i

ba

b

a

b= -here

ia

b is the blade speed ratio

by ma%ing0

/

/=

i

b

a

bd

d

e find 2cos

i

optimumiab

= 5 ma! ib 2cos= 5 po er; 22 bm

The velocity diagram ill be+

b

ae

mr i

a i < r e

b

ia

b

optimumia

b

ma!b

b

iab

optimumia

b

ma!b

b

mr i

r e

ai

ae