The Noise and Vibration Characteristics of a Reciprocating Compre.pdf

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Purdue University

Purdue e-Pubs

International Compressor Engineering Conference School of Mechanical Engineering

2000

Te Noise and Vibration Characteristics of aReciprocating Compressor: Eects of Size and

Prole of Discharge PortH. ErolIstanbul Technical University

A. GurdoganARMAS A.S

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Erol, H. and Gurdogan, A., "Te Noise and Vibration Characteristics of a Reciprocating Compressor: Eects of Size and Prole ofDischarge Port" (2000).International Compressor Engineering Conference. Paper 1450.hp://docs.lib.purdue.edu/icec/1450
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THE NOISE AND VIBRATION

CHARACTERISTICS

OF A

RECIPROCATING

COMPRESSOR: EFFECTS OF SIZE

AND

PROFILE

OF

DISCHARGE PORT

Abstract.

HalukEROL

Istanbul Technical University, Faculty ofMechanical Engineering,

Gumussuyu, 80191, Istanbul, Turkey.

Ahmet GU RDOGAN

ARMAS AS. R&D Department,

Umraniye,

81260,

Istanbul, Turkey.

Reciprocating compressors commonly used in break systems of trucks and buses are one of the

major sources of noise and vibration. At design stage it is very important to find the optimum

cross sectional area and the profile for discharge hole on the intermediate plate. In this study, the

noise and the vibration characteristics of a single cylinder, reciprocating piston compressor used

in break systems of heavy-vehicles are investigated and the results are compared for four

different constructions of a compressor discharge port. A number of noise and vibration

measurements are made at several operating conditions using four different intermediate plates

for the same compressor. The results presented in this paper have demonstrated the effects of the

cross sectional area and the profile of discharge hole in terms

of

the noise and the vibration

levels

of

compressor.

INTRODUCTION

A reciprocating compressor operates on a repeated step cycle process. The piston moves down

on its suction stroke causing a flow ofgas to enter the cylinder until the piston reaches the end

of

that stroke and then proceeds on its compression stroke. At this point the flow into that cylinder

is stopped and remains so until the next suction stroke commences. On the discharge side, as

soon as the internal pressure reaches the level in the discharge port plus the pressure required to

open the valve, the valve opens and gas starts to flow immediately from the discarge port. As

soon as the piston has reached the end

of

the compression stroke the valve closes and the gas

flow stops. This on-off flow process causes noise and vibration in discharge port and its

connections.

Air compressors are the source of energy for break systems using compressed

air

The

compressed air is not only used by the break system but also by some other vehicle components

such as pneumatic suspension, door control etc. The crankshaft of the compressor is directly

connected to the vehicle engine through a v-belt or a toothed gear

in

traditional break systems.

Fifteenth International Compressor Engineering Conference at

Purdue University, West Lafayette, IN,

USA-

July 25-28, 2000

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Schematic diagram of the reciprocating compressor used in this study is shown in Fig.1. The

speed

of

compressors used by the break system

is

dictated by the speed of the vehicle engine.

The compressor speeds vary 1000 rpm to 3000 rpm

in

normal operating conditions. The diameter

ofthe

piston is about 92 mm and the stroke is 37.6 mm The sweep volume of the compressor is

252.5 cm

3

.

At design stage it is very important to find the optimum cross sectional area and the

profile for discharge hole on the intermediate plate. Schematic diagrams of the conventional

intermediate plate and the new design intermediate plates used in this study is shown

in

Fig.2.

Fig l Schematic diagram

ofthe

reciprocating compressor.

In this study, effects of the form and the size of discharge port on the noise and the

vibration characteristics

of

the compressor were investigated by performing several

measurements. The measurements were carried out on four different intermadiate plates on the

same compressor. In order to compare the effects of four different intermadiate plates, the sound

power and the vibration levels of the compressor at several operating conditions were measured.

EXPERIMENT L SET UP

Measurements are made on the compressor itself in an anechoic room which is designed to

provide the same operating conditions

as

break systems of trucks and buses. The anechoic room

is divided into two sections. In the first section there are all the required components for the

compressor. These are an AC motor for driving the compressor, a frequency controller in order

to control the speed of the compressor, an oil pump, an air reservoir and a coolant water pump

and a water reservoir. The compressor is located in another part of the room and it is connected

to the

AC

motor in a way similar to the connections to the trucks and buses.

Acoustic intensity methods offered a number of

advantages over traditional measurement

methods, and therefore acoustic intensity method is opted in order to determine sound power

levels

ofthe

compressor. The sound power analysis is based on sound intensity measurements

in

conjuction with Briiel Kj::er Noise Source Location software type 7681 [1]. The measurement

surface on which the measuring points are located

is

a cubic grid enveloping the compressor in

order to measure sound power according to ISO 9614-1 standard [2]. There are 84 points on the

surface for measuring sound intensity.



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uly 25-28, 2000

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Schematic diagram ofthe experimental set-up and the anechoic room used

in

this study is

shown in Fig.3. Both the vibration and the noise measurements are made while the compressor is

operated at different pressures

of

air reservoir and different rotational speeds

of

crank shaft.

Briiel Kjrer dual channel real time frequency analyzer type 2144

is

used for these

measurements.

(a) Design A

(b) Design B

(c) Design C (d) Design D

Fig.2. Schematic diagrams

of

the conventional and the new design intermediate plates.

The measurement

of

sound intensity and vibration levels are carried out under the steady

state operating conditions. Sound power measurements are performed with Briiel Kjrer sound

intensity probe type 3548 with a 2

mm spacer. The microphones are calibrated by a

Briiel Kjrer sound intensity calibrator type 3541. Vibration measurements are performed with

Briiel Kjrer accelerometer type 4371. A computer is also used for the permanent digital data

storage. The accelerometer

is

located on the cylinder head

in

the direction along with the piston

movement.

RESULTS AND DISCUSSION

Fig.4. presents comparisons

of

the vibration levels using four different intermediate plates for the

same compressor at different frequencies. The effects

of

the pressure

of

the air reservoir on the

vibration levels of the compressor, as one

of

the changing parameter, are shown in this figure.

The pressures of air reservoir are selected as 0 bar, 3 bar, 6 bar and 9 bar respectively. And also

the effects

of

the crank shaft rotational speed on the vibration levels

ofthe

compressor are shown

in this figure separately. The crank shaft rotational speeds are selected as 1000 rpm, 1500 rpm

and 2500 rpm respectively.

Measurements presented

in

Fig.4. are used to establish the main components

of

the

vibration spectrum at two frequecies. These are the fundamental frequency

of

the vibration

related to the unbalance

of

the slider-crank mechanism at the rotational speed and the second

harmonic

ofthe

fundamental frequency.



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July 25-28, 2000

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O

verall v

ib ration

levels

are co m

pare d

fo r fou

r differ

en t inte

rm edia

te plate

s for th

e same

co mpre

ssor at

differen

t press

uresof

the air r

eservoi

r

a

s sho

wn in

Tab le 1

This

giv es a

n idea on

th e perf

orman c

e

o

f fo

ur diffe

rent in

termed i

ate pla

tes acco

rd ing t

o the d

ifferent

pressu

res of

t

he

air res

ervoir a

nd the

differen

t crank

sha ft ro

ta tiona

l speed

s.

Freque

ncy

Anal

yzer

Fi

g.3 . Sc

hem atic

d iagra

m of

the expe r

im ental

set-up

andthe

a necho

ic room

.

Results

of th e

vibrat

ion me

asurem

ents ma

de at s

everal

operatin

g cond

itions

using fo

ur

diffe

rent int

er media

te plate

s have

de mon

strated

the sup

erior p

erform a

nce of

de sign

-D in te

rm s

of o

verall v

ibration

levels.

Fi

g. 5

pr

esents c

om pari

sons of

th e so

un d po

wer lev

els usin

g four

differe

nt inter

med iate

plates fo r the sam e co mpres sor at different frequencies. The ef fects

of

the pressure

of

air

r

eservoi

r on th

e sound

pow e

r levels

of

the

co mpr

essor as

one o

f the

varying

pa ram

eter ar

e

show n

in this

fig ure

. The p

ressure

s

of

th e

ai r res

ervoir a

re sele

cted as

0 bar

3 bar

6 bar and

9

bar res

pectivel

y. An

d also

the effe

cts of

th e cra

nk shaf

t ro tatio

nal spe

ed on

the sou

nd po w

er

leve

ls

of

h

e comp

ressor a

re show

n in thi

s figure

separa

tely. Th

e crank

shaft r

ota tion

al speed

s are

selec

tedas

1000 rp

m 150

0 rpm a

nd 2500

rp m r

espectiv

ely.

O

verall s

ou nd p

ower le

vels ar

e comp

ar ed fo

r fo ur

differen

t in term

ed iate

plates

for the

s

am e co

mpress

or at d

ifferent

pressu

res of t

he air r

eservoi

r as sh

own in

Table 1

This

gives

an

idea on

theper

fo rman

ce of fo

ur diff

erent in

termed

iatepla

tes acco

rd ing t

o th e d

ifferent

pressur

es

ofthe

ai

r reserv

oi rand

th ed if

ferent c

rank sh

aft rota

tional s

peeds.

Resu

lts of t

he soun

d pow

er mea

suremen

ts mad

e at se

ve ral o

per atin

g con d

itions u

sing

four different in ter med iate plates have dem onstrated small differences in terms

of

overall sound

pow

er level

s. How

er ver d

esign-D

show s

better

per form

an ce th

anthe

oth ers

in term

s of ov

erall

sound

powe

r levels.

Fifte

en th Inte

rn ationa

l Compre

ss or Eng

ineering

Conferen

ce at

Purdue

Universit

y West L

afayette

IN

USA July

25-28 20

00

68


6/9

~ . : . ; + 1 ~ ~ : ~ rr

T

Design A

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w i - . - - - - - - ~ - - - - ~ - - - - ~ - ~ - -

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~ - - ~ , ; - - , - t

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Design D

Fig.4. The vibration levels using four different intermediate plates for the same compressor.


Purdue University, West Lafayette, IN, USA- July 25-28, 2000

681


7/9

CONCLUSIONS

In this study, effects of the form and the size of discharge port on the noise and the vibration

characteristics of the compressor were investigated by performing several measurements. The

measurements were carried out on four different intermadiate plates on the same compressor. In

order

to

compare the effects of four different intermadiate plates, the sound power and the

vibration levels of the compressor at several operating conditions were measured and the results

presented in this paper have demonstrated the superior performance

of

the new desings in terms

of

the noise and the vibration levels.

Results obtained in this study will

be

usefull data for the design

of

the noise and the

vibration reduced compressor for the break systems.

T l 1 0e

b

t rattan anera d d

I fi

fi d ffi

d

oun power eve s

or our

1 erent mterme tate p ates.

Overall vibration Levels [dB]

Overall noise Levels [dB]

ref.1.0E-06 m/s2

ref.1.0pW

The pressure of

Crank shaft rotational

speed

Crank

shaft

rotational

speed

[rpm]

air reservoir

1000rpm 1500rpm 2500rpm

1000rpm 1500rpm

2500rpm

Intermediate Plate Design A

o bar

111

114 119

66

72 82

3 bar 112

116 117

79

81 81

6 bar

112 115 115

82

85 84

9 bar 112 115

116

84

87 86

Intermediate Plate Design B

0 bar

96

98

103

66

70

83

3 bar 97

101

103

77

80

81

6 bar

101

104

104

82

85 82

9 bar

102

104 104

83

86

84

Intermediate Plate Design C

0 bar

98 102

106

70

73

83

3 bar

102 103 105

79 82

81

6 bar

103 104 106 83 86 86

9 bar 103

106 106

85 88

88

Intermediate Plate Design

0 bar 95

99

102

65 69

81

3 bar

100

101

103

77

79 79

6 bar

101

103

103

81 83 81

9

bar

103 103

103

82 84

84

REFERENCES

[1] Bri.iel Kjrer Noise Source Location software type 7681.

[2]

ISO

9614-1: 1993

Acoustics - Determination of sound power levels of noise sources

using sound

intensity

Part 1: Measurement at discrete points.


Purdue University, West Lafayette, IN, USA July 25-28, 2000

682


8/9

Desig

n A

Design C

< M ~ - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - = ~

- = - - ~ ~ ~ : j

~ + - - - - - - - ~ = -

- - - : o ~ , . - - ~ - - - -

Q

~ - - -

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- - - = ~ = : _

;_.=""=j

L ~ ~

~ ~ ~ c

1-- .

_-c,_._.-_

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---"- '- :_-___:'-,-.

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,

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,-

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=

freq

uency [}b

~ , 1 - -

- - - - - - - - - - - -

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f

1

pN , , _ o - : - ' - - c

' : - - _ .

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l i

Iii

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. :

.-

1 - = - - - - - r - - - - - - - - -

. - - - = - - - - - ~ ~ - - - - - -

- - 1

/

: ~ r - -

- - - - - - - - - - - - - - - -

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- - ~ - - ~ ~ ~ - - - r l -

-

nqUVJCV(th)

(c)

(d)

D es ignB

h ~ ~ } - : , 6:

Design D

Fig.S

. The noise lev

els using four

different interm

ediate plates

for the same co

mpressor.

Fifteenth Interna

tional Compresso

r Engineering Con

ference at

PurdueU

niversity, Wes tL

afayette, IN, USA-

July 25-28, 20

00

68


9/9

Fifteenth Inte

rn ational Compres

so r Engineering C

on ference at

Purdue University

W est L afayette

IN

US

July 25

-2 8 2000

68

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