r AD—AOÔ9 087 DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CE——ETC F/G 20/1

~~ NOISE RADIATION FROM SUBSONIC AIRFLOW THROUGH SINGLE AND MULTIH——ETC (IJ)
I

FEB 79 F C DEMETZ. M F MAT IS , R S LANGLEY

UNCLASSIFIED DTNSRDC/SAD 237E 19k2 NL

_ U
U.
_

~~~~~~~~ END
_

I-i _ _ _ _

F ILMED
-—
-

~~

I:. _ _ _ _ _
ITT DAVID W. TAYLOR NAVAL SHIP
~ RESEARCH AND DEVELOPMENT
.Md. 20084
CENTER
Bethesda
~~~~~~‘

p
NOISE RADIATION FROM SUBSONIC AIRFLOW THROUGH
uO
~~ SINGLE AND MULTIHOLED ORIFICE PLATES

by DDC
r n1fl
F.C. DeMetz,M.F. Matis
R.S. Langley, J.L. Wilson
~~~
It ~~ ~
tm( 29 1
~
‘
~~

H
C
APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED
.1
~~

H
I SHIP ACOUSTICS DEPART MENT
EVALUATION REPORT
U.
z
On
—w

79 05 25 040
February 1979 SAD-237E-1942
I t .

~ T - ~~~~~~~~
~~~ ~
—~~
 - -

I,

MAJOR DTNSRDC ORGANIZATIONAL COMPONENTS

DTNSRDC
COMMANDER
00
TECHNICAL DIRECTOR
_ _ 01

OFFICE A-IN-CHARGE I OFFICER-IN-CHARGE

CARDEROCI( -
I ANNAPOLIS
05 1 04

SYSTEMS
DEVELOPMENT
DEPARTMENT
~

PERFORMANCE
[SHIP SURFAC E E ECTS
~~
_ _ _ _ _ _ _ _ _ _

COMPUTATION

17 LOGISTICS DEPARTMENT

PROPULSION AND
SHIP ACOUSTICS
AUXILIARY SYSTEMS
DEPARTMENT
19 DEPARTMENT 27

SHIP MATERIALS CENTRAL

ENGINEERING INSTRUMENTATION
DEPAR TMENT DEPARTMENT
29

. iiTi1i~~
: ~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~
—- — -
~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~
 -
-- - - - - — —
F_,*•_ ~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~ ~~~~ ~~~~~~~~~~~~~~~~ -

~
~1

UNCLASSIFIED
SECURITY CLASSIF ICAT ION OF T HIS PAGE (IThen D.ia tnI•ts4~ __________________________________

RE A D INSTRUCTIONS
REPORT DOCUMENTATION PAGc BEFORE COMPLETING FORM
I. REPORT NUNSER 2. GOVT ACCESSION NO ~~.#.WE C1ç IENT’S CATALOG NUMEER

SAD—237E—1942 .1 j
~
/
~~~~~~
4- T ITL E (ond SubtUl•~ ~~~~~~~~~~~~ ...o w r O cOv ERED

NOrSE~~ ADIAT]oN FROMJUESONIC#AIRFLOW THROU~~ J Interim

• JINGLE ANDJIULTIROLED ORIfiCE PLATES
~ . s r ~ nr ~ r - ~~ ~~~ T NuMSER

jG
[ uTHOR(.)
~~
eM
~~ ~~~~
M.F.1Matis
—i S. CONTRAC T OR GRANT HUMEER(I)

R.S.jLangley J.L.J~~ 1so~~j

—

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

I. PERFORMING O RGANIZATION NAM E AND ADDRESS 10. PROG~ AM ELEMENT. PROJECT . TASK
David W. Taylor Naval Ship Research / Program Element 61152N
and Development Center Task Ar ea ZR 011080 1
Bethesda, Maryland 20084 Work Unit 1942—089
~~ 7
II_ CONTR0LLING OPFICE NAME ANO ADDRESS ~~~~~~~~~~~~~~

~~ -
‘ nun~~c~~ Jr

_____________________________________________________ 38
14. MONITORING AGENCY NAME S AO DRESS(t f dSU•r,n S ho., Confrottin Oti’ic.) IS. SECURITY CLASS (of hi. r potf)
/
~~~~~~ ‘
__
_____
_____

(Jt/ 179sRJ 4/SA.D -

IS..

~— 1
..—
~~~~~ SCHEOULE
-.
—

/ ~ 7,LJ
IS. DISTRISUTIOI4 STAT EMENT (of (hI. Rsport)

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED r’)

I?. . 1*. b h C f o.firsd Sn lionS 20, ii ~~ f5pAont
DISTRISUT ION STATEMENT (
1 hon. R~~ont)

IS. SUPPLEMENTA RY NOTES

• 10. KEY WORDS (Ccn*Mu. on o

t ,,
... iSdo Si nic•• y
~~ on~ idw,fS~ ’ Ip U.ck n. hoe)

-j -s-- Noise reduction, subsonic airflow, orifice plates, velocity field ,

radiated pressure , broadband components, tonal components, radiated

79 5
noise field C
20. *0 TRACT (Co.dnu. on , v io
~~ .5* ~
11n.coon.p ond Sd.nf* Sv bl..k .n b.o)

The mechanisms and scaling laws for noise radiated from subsonic air—

t
flow through single and multiholed orifice plates have been studied ex—
perimentally. Simultaneous measurements were conducted of the velocity
field and radiated pressure associated with jets formed downstream of
sharp—edged , multiholed orifice plates. The orifice plates, containing
(Continued on reverse side)

DD ~I
1473 £OIT’ON IN IS 0010L ITI
UNCLASSIFIED
P
3’~~ 7 ~:
SECURITY CL.A$$IPICATION OP THIS PROC (US... Don . ~~~~~~~~~
~ ~f
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ -

: i - ~~- i
~~~~~j •
:. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 UNCLASSIFIED
DSCUII?Y CLASSIFICATION OF THIS PAGE (US... Don• 4on.I
~~ -

(B ock 20 continued)
‘
•
from 1 to 31 holes , were placed at the termination of a quiet 76—
millimeter inside diameter airflow facility . The characteristics
of the broadband and tonal components of the rad iated noise f ield
are evaluated in terms of: ( 1) the orifice plate hole geometries
and flow interac tions and (2) the downstream jet features.

br
~~~~
‘ NflS
~
1DL ~C

•_i~•~
81 i’ I-
~ v - ~~ ~ ~

\ 9~~9~~ ”•~
-
~~~~

. •

UNCLASSIFIED
SECURITY CLASSIFICATION OP THIS PAGt (WS..n bona g
I
(
.
, d
)

— --- ----- ---——---

--- -
- -
------ --, -•-
~~~~~ ~~~~
---- -- - - - - •- - - - - - -- --
~~~~~
 S
TABLE OP CONTENTS

Page

LIST OF FIGURES . . . . . . . . . . . • • • • • • • • • •

NOTATION . ....... v

ABSTRACT . . . . . . . . .

ADMINISTRATIVE INFORMATION 1

INTRODUCTION .. 1

REVIEW OP NOISE GENERATION MECHANISMS. . .... 2

FLOW—OSCILLATOR FEEDBACK MECHANISMS 5

EXPERIMENTAL APPARATUS 7
TURBULENT AIR PIPE FLOW FACILITY 7
INSTRUMENTATION 7
ORIFICE PLATES 10

EXPERIMENTAL RESULTS 10
SPECTRAL FEATURES OF RADIATED NOISE 10
TONE FREQUENCY VARIATION WITh FLOW VELOCITY 10
NOISE AMPLITUDE 15
Broadband Levels 15
Tone Levels 20
ORIFICE—JET VELOCITY FIELD 20
Mean Velocity Profile 20
Fluctuating Velocity 20

DISCUSSION 20

CONCLUSIONS 25
•

RECOMMENDATIONS 26

ACKNOWT..EDG~(ENTS • 26
S
REFERENCES 27

I
iii

-
— —- -- S
-
~~

S
5
-- 5 .5 — —~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3
- — -

~~~~~~~~
~~~~~~~~~~~~~ ~~~~~~~
 5•55
~~ .5 ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~-.--—

LIST OF FIGURES

Page

1 — Mechanisms of Noise Radiation from Interacting

A ir Je ts 3

2 — Flow/Osc illa tor Mechanisms 6

3 — Turb ulent Air Pipe Flow Facil ity 8

4 — View of 7—Hole Orifice Plate at Termination of

76—Millimeter Inside Diameter Air Pipe 9

5 — Types of Orifice Plates Tested. . ... 11

6 — Radiated Noise Spectra Velocity Dependence

for a Single Je t 12

7 — Frequency vers us Flow Veloc ity for Acous tic Tones

Genera ted by Flow through Mul tiholed Or ifice
Plate (d/ t l, N~ 7) 13

8 — Frequency vers us Flow Veloc ity for Aco us tic Tones

Genera ted by Flow through Multiholed
-

Orifice Plate (d/t=4, N=7) . 14

9 — Strouhal Number versus d/t for Acoustic Tones

Genera ted by Flow through S ingle and
Multiholed Orifice Plate~ 16

10 — S tro uhal Number vers us Reynolds Num ber for Acous tic ‘

To nes Genera ted by Flow through S ingle and

Mul tiholed Or if ice Pla tes 17

11 — Velocity Dependence of Radiated Broadband Noise

Generated by Flow through Single and
Multiholed Orif ice Plates 18
I
-

12 — Normalized Maximum Radiated Broadband Noise

Levels versus d/t at U / C = 0.32 19

13 — Maximum Radiated Tone Levels Generated by

Multiholed Orifice Plate versus d/t (N—7) ... 21

14 — Comparison of Mean Veloc ity Prof ile of

Adjacent Je ts with that of Single Je t 22

15 — Peak Fluc tuating Velocity a t F

Her tz vers us x/d
— 8120
.. 23

iv

c
- —
~~~~~
-5--- — —‘ —~~ -— — ~-~~~~~ -S--- ~~~~~~~~~ — - _____
 ‘
_ _ _ _

~~T

NOTATION

c Speed of sound in undisturbed fluid

d Diameter of orifice

F Frequency
S M Mach number (— U/c) -

N Number of holes in orifice plate

2 Time—averaged mean square acoustic pressure in the free field

p

Pjj Stress tensor (Reference 24)

S
q(P) Amplification factor

R Radius of or if ice

r Distance from sound source to observation point

S,S Surface increment

1

T Tensor (Reference 24)

ij

t S treamw ise length of or if ice

U Convection velocity of fluctuating velocity component in

C
orif ice je t

U Maximum orifice jet exit velocity

e -

u,i Mean flow veloci ty in or ifice

Peak value of time averaged fluctuating velocity

V Volume increment

Velocity component at point in fluid

W Radiated broadband sound power

x Streamwise distance from downstream edge of orifice plate

Spa tial coordinate

__________________________

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ - - - 5,

_ --.
f l~ ~ 5 _ _ _ _ _ _ _ _
_ _ _ _ _ _ _

4.
x Vector spatial coordinate

I +
y Vector spatial coordinate

y Transverse distance from center of orifice

Pressure drop across orifice plate

Kronecker delta

Feedback effectiveness

A Wavelength of disturbance

p Density of undis turbed fluid

v Kinematic viscosity of fluid

vi

- -_ _ _ _ _ _ _ -- 5- -S
- —
~~~~-- -. --5

5 ,5~
. .S, ~ - - ,
-- . -
_________________________________
— 5— — ~~~~~ ~~~~~~~~~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ABSTRACT
The mechanisms and scaling laws for noise
radiated from subsonic airflow through single and
multiholed orifice plates have been studied exper—
S

imentally. Simultaneous measurements were con— i —

ducted of the velocity field and radiated pressure

associated with jets formed downstream of sharp—
edged , multiholed orifice plates. The orifice
plates, containing from 1 to 31 holes, were placed
at the termination of a quiet 76—millimeter inside
diameter airflow facility. The characteristics of
the broadband and tonalcomp onents of the radiated
noise f ield are evaluated in terms of: (1) the
or ifice plate hole geome tries and flow interac tions
and (2) the downstream jet features.

ADMINISTRATIVE INFORMATI
ON
This study was supported by the In—House Research Program of the
David W. Taylor Naval Ship Research and Development Center under Task Area
ZR 0110801 , Element Number 6ll52N , Work Unit 1942—089.

INTRODUCTION
The generation of noise when air moves through multiholed orifice
plates is associated with vortex creation . The complex structure of the
velocity and pressure fields associated with these vortices requires the
utilization of experimental methods in conjunction with similarity theory
and dimens ional analys is to prov ide insight into sound generation and
prevention mechanisms . This report presents measurements of noise produced
by turbulent pipe flow through orifice plates containing single and multi-
ple cylindrical holes. An understanding of both the broadband and tonal
noise generation processes of the orifice related flow is desired.
Extensive experimental work on tones produced by flow through single
l_7*
orifice elements was conducted by Anderson over two decades ago. He
determined relationships between jet—tone Strouhal number , the orifice
Reynolds number , and the orifice thickness to diameter ratio .

*A complete listing of references is given on page 27.

5
1

— -5
- 1r 1ur 1 p.
f
. -1
~~~~~~~

—5-5-— — 5- .— . 4
’,-~~ .-SS,--..-—-- - -
SsS ~~~~~~~~~~~ 5~~~~~~~~~~~~~~~~~ 5- -•~
-‘•—-- I~Z — ~~~~~~
~~~~~~~~ 5- ~~~~
___________________________________
~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~ ~ ~
 Other relevant studies address acoustic and hydrodynamic feedback
8-11 12,13
processes in flow—oscillators and flow— sound interaction processes .
14
Iudin developed a methodology for an experimental investigation of
primarily broadband noise created by flow through air—duct elements.
Many other informative articles on the features of broadband noise associ-
15 2°
ated with subsonic air jets are available. Noise from flow through air
gratings is discussed in Beranek’s book on noise control.2’ O ther ar ticles
relevant to noise by flow through vibrating multiholed plates are given
22
in a paper by Chen on vibrations of tube arrays excited by crossf low.
Of course, s tudies of aeolian tones generated by vortex shedding from iso—
lated cylinders goes back into the 19th century , as discussed in papers by
23 24
Stowell and fleming and Phillips. There are also numero us purely
hydrodynamic studies on periodic and random eddy structure in jets which
25 34
are relevant to the present study.
The objective of the present study is to experimentally determine the
basic features of flow-structure and flow—acoustic field interactions of
mu ltiholed or ifice plates. The experiments were designed to determine the
scaling laws for the tonal and broadband noise radiated both from the flow
through single and multiple orifice openings and from the subsonic air jets.
S imultaneous measurements were made of the veloc ity field and rad ia ted
pressure associated with jets formed downstream of sharp—edged orifice
plates. The orifice plates, conta ining from 1 to 31 holes w ith diame ter to
thickness ratios d/t from 0.25<d/t<8, were placed at the termination of a
• quiet 76—ms inside diameter (I.D.) pipe airflow facility. The properties
S
of the single and multiple orifice and jet—flow—generated noise were mea—
sured for a range of Reynolds numbers, based on orifice streamwise thick-
ness and orifice flow veloc ity U from lO 00O<U t/V<76O O0O •
e~ ~ e ~

REVIEW OF NOISE GENERATION MECHANISMS

Figure 1 illustrates the basic radiated noise—producing mechanisms of
flow through rigid , mul
tiholed , orifice plates producing turbulent down-
stream jets. The possible noise—generation mechanisms are those associated
S
with monopole sources in the orifice—plate openings, dipole so urce s due to
fluctuating drag forces on the plate structures or interacting vortices,
and quadrupole sources in the turbulent jets downstream of the plate.

—--— - - 5-
-~~~
- -

- - - - ~
.
- ..—..—— ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5 - -.
-” - - ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 T T
- 5 5 5-5 5
-
-—-—--
-- - - - - -
‘: ’--1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
~~~ ~~~~~~~~~~~~
~~~~ ~~~~~ ~~~

w
4
C

)t
~~~ ~

4 t~~Y~~
~
G
5 ,-,
S

r~
. 5 5 .
h
‘
)~ I.
O 4
Z~~.rI
I ~
o~~o

~~

I
H.
• _

- ,M .

- S .
__ ~~~~~~~~~~~~.5-
- - -

k. ~~~~~~~~~~
— - -
~ ~
-
~~~~~
—5- .- —~~---.----- S 5S-
-- --- ~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~
-~~-—- -. i~~~~ ~~~~~~~~~~~~~~~~
~~~~~~
~~~~~~~~~~~~~~~
 — .---- -.----
- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The radiated sound power W dependence on flow velocity is shown for each
14
type of source. ’2’ If s tr uc tural v ibra tions occ ur in the or if ice
plate , additional monopole sources would be associated with boundary motion .
The noise produced from these structural and flow fluctuations acting
independently can be expressed by an equation similar to that given by
24 for aeolian tones. Phillips utilized Curle ’ 35 adaptation of
Ph
lilips s
Lighthill’s theory for density fluctuations (proportional to sound pres—
S
sure) due to flow over solid boundaries to arrive at the following
expression

= -
T ~ ()dVG)
2 ~~~
1
4lTc ~x x J
-

S Volume Distribution
of Quadrup oles

+
- —f (Pv~v~+1~~~)dS ( ) (1)

~
— -- - -
~~
1
~~ ~~

Distribution of Dipoles due to

S urface For ces on Fluid

a(pv )
— dS~ (y)
at
471c2J ~

S
Monopole Sources due to
Bound3ry Motion and Flow
Fluctuations in Hole

tz

..
_ _ _ _ _ _ _ _ _ _ _ _ _ _S
—S--
t
— - 5-- — -—5
— - —55-—-

t - _- --.—~~~~~ ~~~ . — .
.~ . ~~~~~
~~
~~~~~~
 55 55 S _~
—~S55-S5-S_~~5~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ U 5-l ‘~
pI Ip
, -5--S.—- - - — S
~~~

I where p and c are the density and sound velocity in the undisturbed fluid ,
v and Pj are the velocity and stress tensor in the fluid ,
r — I x—y l , and ~~ — PV V + P c p6 . The use of this equation to
—
1 J jj ~~
calculate the sound field requires the detailed knowledge of the flow and
36
structure properties and is , therefore, of limi ted usefulness in orifice
plate noise studies. The effects of feedback suggested between the three
types of sources given in Equation (
1), when orifice—plate flow tones
occur , add additional complications to an analytical determination of the
sound field.

FLOW-OSCILLATOR FEEDBACK MECHANISMS

1~igure 2 illustrates the possible flow—oscillator mechanisms when
structural or acoustic feedback is present . At resonance the nonlinear
discrete vortex driving field downstream of the hole interacts with a feed—
back mechanism provided by acoustic, aerodynamic, or structural distur-
bances. The feedback loop shown in the figure is similar to that proposed
by Chanaud and Powell ’0 in the study of hole or ring tones . Random dis-
turbances in the flow are assumed to disturb the jet in the orifice plate
openings with some efficiency . The ~natabil
ity frequency components of
~~~~~~

the jet disturbance will be amplified by an amount of q(F) as they convect

downstream . When these amplified fluctuations in the jet reach a down—
s tream “reflector” , a fluctuation is created with interference efficiency
This fluctuation can generate an aerodynamic or acoustic pressure
f ield and transmit disturbances ( i . e . , provide a direc t feedback path)
back to the jet disturbance on the plate opening with efficiency T1 (l). If
D
these downstream disturbances , which are transmitted upstream to the
origin of the jet instabilities , arrive with the proper temporal and
spatial relationships they can amplify the instability fluctuations and
close the feedback loop to provide a large amplitude resonance in the
flow—oscillator system.
The other possible direct feedback mechanisms for the jet instabili-
ties are shown as the vibrations transmitted through the structures ,
and the interjet interactions , Tl (3) .
fl

- -w -
— ---.- r —‘ -
~~
55
- ~~~~

- -S
5,.
I. — _-- .—.— ~~~~~~~~~~~~~ - --5 - --. -
 —5- --_____________________
= ____________________________
- - — -~~~~~

(3)

_
$ 7 ~i

••
)• ?? (1)
u r ~~~ ~~ ~~ o
nI (1)
/ flj~~~~ J ns -* vi~(2I
~ ~~~~~~~
_
/
~~~~ ~~~~~
~~~~
_,11

\\\\\\
~ ~~~\ \ \ \ \ \~~~~\~~ \ \\ ~~

TRAN SMISSION
DIRECT FEEDBA CK
ACOUSTIC
‘ 12 STRUCTURAL
~D ~
AERODYNAMIC

DISTURBANCE
OF JET
f AMPLIFICATION (q)
BY
UNSTABLE JETS
... ~~
INTERACTION
AT DISCONTINUITY
S

\~ TRANSMISSION
INDIRECT FEEDBACK
UPSTREAM
DOWNSTREAM
RADIAL

~ FEEDBACK EFFECTIVENESS
q = AMPLIFICATION FACTOR

Figure 2 — Flow/Oscillator Mechanisms

(Structural and/or Acoustic Feedback)

iIi~~~i
~
-

~~~ ~
_::_ ~~~~~~~~~~~ ---
~~
—
~~
LJ .J~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
~~
- -
~~~ ~~~
 -5 --S.—- -
5 555
~~~~ ~~~~~~~~~~~~~~~~~~~~

Other disturbances which may be of sufficient magnitude to interact

with the jet instabilities are denoted in the figure as possible indirect
feedback mechanisms. These are disturbances arriving from upstream 1) (1),
1
downstream fl (2), or perpendicular to the jets which are produced
~ ~~~~~
by fluctuations or reflections from obstructions or boundaries somewhat
remote to the orifice plate.
It is important to note that all the direct and indirect disturbances
considered in this functional diagram originate ultimately from the
unstable jet fluctuations. It is conceivable, however , that externally
excited acoustic , aerodynamic , or structural disturbances could also create
the conditions necessary for strong acoustic tone generation by the orifice
flow—oscillator.

EXPERIMENTAL APPARATUS
TURBULENT AIR PIPE FLOW FACILITY
The turbulent air pipe flow facility in which the experiments were
conducted is shown schematically in Figure 3. The air from the high—
pressure storage tanks is passed through a f i l t e r and regulator system
which provides constant flow velocity at the test section (orifice plate).
The low—pressure settling tank and fiberglass—lined , baffled muffler
reduces control system noise and provides a fully turbulent, low—noise flow
into the orifice plates . The pipe flow velocity and orifice velocity are
determined from strip chart recordings of the pressure drop along a length
of the test pipe and across the orifice plate, respectively.

INSTRUMENTATION
Figure 4 shows a photograph of a 7—hole orifice plate at the termina-
tion of the 76—ms test pipe and the location of the free field pressure
transducer. Small hot film and hot wire sensors were mounted on the
positioning device and used to survey the mean and fluctuating
features of the jet flow field downstream of the orifice plate. For some
measurements a pinhole microphone was mounted flush with the pipe wall S

0.6 m upstream of the orifice plate to measure orifice noise inside the

=-
- -
- -5— .--S~’.-- SS ~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~ -S _ .....S I
~~~~~~~~~~~~~~~~
~~
_ _
~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ ___ _•~ J••j5~~~~~ ~~~~~~~~~~~ .
.
A ~~~ ~.
~~~~
 .5,. .r’
~r- - -
S~~~ ~55-S • S S
-SS-55S5--5-SS-5-5-S ~~~~~~~ -5 S55-~~~~~ .sS- s . s. S 55-5-S-55-5-5 S5 -
S
~
---5- 5,!
~~~~S~~~~5,~~ ~~~ ~~~~~~ ~ ~
--- ’- ~-
-5,-- - S~_— ~~~~~~~ ~~~ ~~~ ~~
-5--- — — _ _ _ _ _ _ _ _ _ _ 5 5 --

JjTH-4
,

ii
>. .0
1.4
I-

, .
S~~~~~~ . S

5— —5- -5— — 5— . . ,~~- —----,- - —5- — ---5 ~~I~~ S

___________ — — - - - .— ~~~~~~~~~ — 5__~~5 -S 5~ ••~~~~ ~~~ ~~~~ S~I ~~~~~~~~~~~~~~ - ~~~~~~~~~~~
_l
 I

w
I-
5.
w U-4
U 5

0
-

1
—
—
I
—
5.
~
., .u
— U.
S
— U.

- 0—I
0 0. -
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
‘— — ~
.
~~

S
ILl
0 sr— . S

z
o z
I
L
0

.•~.~~i:f
I

- - S 5- 5 S5 .
~~~~ ~~ ~~~

k . _. -- ______________________________ _________________ - ~~~~~~~

. - —
~~~~~~~~~~~~
— .
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -
--

test pipe. No acoustic absorption material was utilized on the steel,

5
wood , and concrete structures located in the test area.
-

ORIFICE PLATES
Figure 5 shows a photograph of the types of orifice plates tested to
study the noise radiated from single and multtholed orifice plates and air
jets. The results reported in this paper include measurements for sharp—
edged steel and aluminum plates with 1, 3, 7, and 31 holes, with diameter
to thickness ratios from O.5<d/t<4. Some plates were also tested with
approximately 0.8 mm bevels on the hole edges.
S

EXPERIMENTAL RESULTS
SPECTRAL FEATURES OF RADIATED NOISE
Radiated noise spectra from a single jet (orifice 25.4 mm d by
7.6 mm t , d/t = 3) for a range of jet exit velocities U is shown in
e
Figure 6.
The typical peak in the broadband features of the noise is seen for
17
U = 61 rn/sec. At U 91 m/sec, a tone is seen to rise out of the
5

e
broadband radiated noise at a frequency F = 5400 Hz. The tone reaches
a maximum amplitude at U = 107 m/sec , with higher frequency components
e
also prescia. As jet velocity is increased still further , however, to
U = 122 in/sec , the tone components drop out. Notice also tha t the
presence of the tone at U = 107 rn/ sec increased the broadband radiated
e
noise by approximately 10 decibels (dB) over the levels at the higher
S

velocity U = 122 rn/sec.

e
These spectral variations with flow velocity are generally representa-
tive of those for both the single and multiholed orifice plates tested .

TONE FREQUENCY VARIATION WITH FLOW VELOCITY

Figures 7 and 8 compare the two observed types of orifice—tone fre-
quency variations with orifice exit—flow velocity U • It is seen in Figure
e
7 that the tone frequency increases uniformly with orifice flow velocity
for a 7—holed plate, with d/t — 1. For the thinner 7—holed plate , with

-_ _ _ _ _ _ _
~~~~~~~~~~~~~~--
- S— S- - S .5 5

--5- - _S 55_5-_ S 5 5 .
~ 5 - - -5 -5 5 .5 ,~ • S 5 S-
5—_I- —— ---55- - ----
~~~~~~~~~~~~~~~~~~~~
—5-- 5 s~~~~~ - ~~5,~ - - - -~~~ 5-5__ S~~_ ~ _ - - ~~~~~~~~ _5-
~~~~~~~~~~~~~~~ ~~~~~ S-~~-~ — ~~~ ~
555
 S - - — 5 -—- —

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
S -. S
~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~
I
- C

.
I
“

•• •
.5 -

-z ~~~

‘a’
S

,a.

a.

0 2 4 68 1 0 12 14
CENTIMETERS

Fi gure 5 — Types of O r i f i c e
Plates Tested

11

- -

_ _
~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_ _
 55 - 55 5 5 5 5
~~~~~~~~~ -—

lx I I I I I I~ I I I I I I I I I
~
I I I 1 1 1 1 1

ORIFICE PLATE d/t 3,N 1 5

-
120

t 110 — —

OR I FICE VELOCITY
/ J
~~~

~ 00~~ 9i— .
~~~~~ -

70 - ~~~~~~~ -

I II 111111 I I I l t i ~~~~~
I I t i l l _ I

100 1,
000 10,
000 100.000
FREOUENCYIHZ S

Figure 6 — Radiated Noise Spectra Velocity

Dependence for a Single Jet

12

S 5 ,-S —.S———
— • _5 _ S
—55 - - - -5 —.5— 5
— - ~ ~~ ~
S-
— ~ ~
‘

_ _ _ _ _ _ _ _ ~~~~~~ s~~~ E~~ &_ ~~~~~~~~~

_ 5-55-
 ____ -
1IU 1

10
I I I I
d /t— l
N-7SHARP HOLES
5
9— —
S

VE LOCITY INCREASING

LDE ~~~~~SIN:
I ~~~~~~~~

61 73.2 85.3 97.5 109.7 121.9 134.1

S

U,
/M/SEC

Figure 7 — Frequei~ y versus Flow Velocity for Acoustic Tones Generated

by Flow through Multiholed Orifice Plate (d/t l, Na7)

13

-w

•
- -v-
1~ - -
- - . ~~~
:j 4v ~~~~~~~~~~~~
—5 — — — . - — - — . — — .- — - — ~~~~ ,

-
—5 -—- -— 5 - — —. .
. . ._ .
.. ______
~~~~~~
--=- -- ~—
. . ~~~~~~ ~~
—
~~~~ ~ ~~ ~~~~~~ ~~~~~~~~
 —5 s s.s s -
_______ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

14
I I
d/t — 4
N - 7 SHARP-EDGED HOLES
TONES DETECTED DOWNSTREA M
12 — IN ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

••
S
1 0— _ —

• ~~~~~

a
‘U

—
TONES DETECTED UPSTREAM —

• S S S I*.I1S SSIIS
~~
2— —

I .
.
I I I I
30.5 42.7 54.9 67.0 79.2 91.4 103.6
U /M/SEC
•

Figure 8 Frequency versus Flow Velocity for Acoustic Tones Generated

—

by Flow through Multiholed Orifice Plate (d/t 4, N 7)

14

- — -_ _ _
-

5,
~~~~~~~~~~~~~~ — -~~~ --
 ~~~~~~~~~~~~~~~~ -5-S
S —
~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~

-— .---- S-S - _ —— . 5—S -

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~

d/t — 4 , the tone frequencies remained constan t for increased flow

S
velocities as shown in Figure 8. Some “hysteresis” effects are shown in
Figure 7 between the increasing and decreasing velocity data. No acceler-
ometers were used to monitor plate vibration amplitudes during the noise
measurements .
Figure 9 shows the observed Strouhal numbers Ft/U versus d/t for the
acoustic tones detected for the single and multiholed orifice flows. The
range of Strouhal numbers decreases significantly with increasing d /t over
the range of test parameters shown. The widest range of tone frequencies
is seen to occur for d It — 1.
Figur e 10 displays the Strouhal number versus Reynolds number for a
range of d/ t ratios and number of holes.

NOISE AMPLITUDE
Broadband Levels
A summary of the radiated broadband noise level dependence on orifice— S

jet exit velocity U is shown in Figure 11. These noise levels were deter-
e
mined from the broadband root mean square (rms)levels of the microphone
spectra (with no tones present) using a Spectral Dynamics model 335
4 8
spectrum analyzer. It is observed tha t power laws from U to U occur
with no apparent systematic depend ence on d / t or the number of orifice
openings N. Comparison of the broadband noise generated by the flow
through the sharp and beveled edged orifices Indicated that the 0.8 nun
bevel reduced the levels by 2 to 4 dB.
Figure 12 shows the variation in the maximum normalized rad iated
broadband noise level detected for each d/t radio studied. The noise
2
level p is normalized in terms of the orifice—jet dynamic pressure, the
total cross—sectional open area of the orifice plate , and the distance
from the orifice plate to the free—field microphone. It is seen that the
maximum nondimensional broadband noise level occurs when d / t 1 for both
N— b r N 31.

I
I

15

.-.
-5.
.--
- -5-~ ~~ ---
- -
:i
_____
I—
p
___ __
~~ ~~~_ ~~~ 11 L~~~ T ~~~~‘~—
~~~~
---
-
_
_ __
_ _ __
_ .5

I
.

2_ k
S

5
Ft 1 N 31
~ ~

1~~~ DATA

NO DATA

0
0 1 2 3 4 5
d/t

Strouhal Number versus d/t for

Figure 9 —
S

Acoustic Tones Generated by Flow through

Single and Multiholed Orifice Plates
S

16

5 5 - - - - - - 5 5-- 5 5 - _ S - S _ _ _ _ _ _
S -

~~~~~~~~~~~~~~~~~~~S S
--
 S--- ~ S-~~~~~~~~
— - - U- - - -

I I I
S

U .’.)

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

17

______________________
-— - 5-S~~~~~ S S555~~ S - S5

S -~~~~~ --~~~ ~~~ -—-S S ---- ~~ —

_ _ _ _ _

- S
-
 5-

140 1
1 1

lx- d/t 1 1

d/t 31 - 1

120 - /‘ d/t 3 - 4
, ~~~~~~~~

2 .“ d/t 31 2
,~~~ d/t 3 - 3

Figure 11 — Velocity Dependence of Radiated Broadband Noise

Generated by Flow through Single and Multiholed
Orifice Plates

18

55 5- .- - 5- 5-55_~
_ _ _ _ _ _ 5- -— - - S - _ S __________
—
~ 5~ - ~~~ ~~~~~~ - S — -S
S
S

_ _ _ _ _ _ _ _ _

~
~S
S— ~~~~~- -- ~S ~~~~~
~~~~~55-
S
S
 —30 1

- NUMBER OF HOLES
-
~
IN ORIFICE PLATE

-80 I I I I
0 1 2 3 4 5

Figure 12- — Normal ized Maximum Radiated Broadband Noise

Levels versus d/ t at U /c — 0.32
C

19

— — S S
~~~ ~~S5~~~~~ 5 5 -S -
5

II
- — - — -S
~~~~~~~~~~~~~~~~~~~~~~~~~ —--—--- -- ---S-__-—S--—-5
~~~~~~
~~~~~~~~~~~~~~~~~~~~~ -.
~~~~
s-
——‘5. -555-- .- .—.. ‘-•~~~ 5S~.5S — SS~~ .S~ S
— —55-5 — ~~~~~~~~~ ~~~~~~~~~~~~~~~~ — —
 ______________________ S -

Tone Levels
The variation of the maximum radiated tone levels from a multiholed
orificc plate (N—7) with d/t is shown in Figure 13. As was the case for
the broadband noise level , the peak tone level also occurs when dlt 1.

ORIFICE-JET VELOCITY FIELD

Mean Velocity Profile
S

The mean velocity profile across a single subsonic jet is compared

with tnat of a jet from a 7—hole orifice plate in Figure 14. Data for an
orifice plate with a single hole compared well with the results of Davies,
27
Fisher , and Barra tt which is shown in the figure. A distinct asymmetry
is seen to occur in the profiles of adjacent jets, the higher mean velocity
occurring on that side of the jet which is adjacent to the neighboring jet.
The transverse dimension y from the center of the orifice opening is nor-
malized by the orifice radius R. Static—pressure surveys indicated lower
pressures near the downstre.~m orifice—plate surfaces between the holes.

Fluctuating Velocity
Figure 15 shows the variation of the tone component in the jet velo-
city spectrum with downstream distance normalized on the single jet
diameter d. The velocity field tone detected with a hot wire had a maxi-
mum amplitude at the jet mixing layer at x/d ~
‘ 0. The peak in the velocity
field spectrum occurred at a frequency of F = 8120 lIz, which corresponded
to that of the radiated acoustic tone. As the hot wire was traversed down-
stream (
increasing x/d) the peak fluctuating velocity indicated that a
stationary wave existed in the jet mixing layer . Based on a wavelength
determined from the successive crests in the figure for the level of the
fluctuating velocity, it is seen that for the wave to appear stationary
it must be moving upstream at U /U — 0.7, which is ap prox imately the speed
c e
at which the mixing layer disturbances convect downstream.

DISCUSSION
The general features of the radiated noise for varying orifice flow
velocities shown in Figures 6—13 were representative of those obtained for
both single and multiholed orifice plates. The noise characteristics

20

_ _

-s
- — S~~~~~~~~~ -.- — —
~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ — 5- _ _ _ _ _______________________
.‘5— ~~--~~~~~~~~~~~~~ .
s55’5~~ _.&5-~~’5 Ss5~~5.5~~~~~~~~~~~ S.55’5.L.5S-5 5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~ ~~~~~~~
———5-.--— — .5. 5— —5— ~~~~~~~~
 5,S5~~~~ S 5-__ 5--S 5- 5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

r—

100

140 - N-7 -

120 - -

100 - -

8 0- -

00 I I I
0 1 2 3 4 5
* d
~

Figure 13 — Maximum Radiated Tone Levels Generated

by Multiholed Orifice Plate versus d/t (N 7)

_____________________
21

5’ __ S
S * ! S S

S - .
-
S

5 5- ~~~~~~~ — - 5 — - 55

-5- .5- ——— . 5 5— 5 -55’ — . — -5 .-.1_55 — s S ~~~~~~~~~~~~~~~~~~~~~~ S ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 -
— _ --55- - S

I ~~~~~~~~~~~~~~~~~~~ 1
‘
S

P /
X I
t
- . -

[I -
y l U
I,
- 0.6
~~

- I, \ 0.4 W
k

-
S

DAVIES. FISHER, BARRATT

~~ JFM I5
Q 55

SINGL: JET
0.2 -. -

ft8 1.2

Figure 14 —Comparison of Mean Velocity Profile of

Adjacent Jets with that of Single Jet

22

--

-- 5- ’ -.
:4~~~a •

~~~~~~~~~~~~~~~~~~~~~~ j - ---
_ _ _ _ _
~~ ~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ~~~

~~~~~~~~ 106 rn/gsa

0.03 -k -

N —7 . d/t • 1

—~~~~ - 1.0
I

‘ I
~~~~~~~~~~~~~~~~~~~~

S
—

U5 — A F — 7 2 m1.sc -
5]

— - .2
S — — 0.68
U.

0 I I I 0
0 0.4 0.8 1.2 1.6 2.0 2.4
xM

Figure 15 - Peak Fluctuating Velocity at

F — 8120 Hertz versus x/d

23

I~~:-
555
IL 1
S~5 5555 .5
—
‘‘ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~

-
~*-+—
— — - —~~~~~ — --— ~~
— —
~~ —
— —
-5-5 ‘
~~~~~~~ -5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~ S - -S~ S - 5S1
~~~~
 — --- - S _ S
5 ~
.5

did not change with small changes in the free—field microphone position
and thus the lack of anechoic treatments to the test environment was not
considered to have significantly affected the reported results. As shown

S
in Figure 6, it was found that acoustic tone onset was associated with a
significant increase (of the order of 10 dB) in the broadband radiated
13
noise in agreement with the results of previous investigators.’2’
The two different types of tone frequency variat~.ons with flow velo-
city shown in Figures 7 and 8 suggest the existence of two distinct feed-
back mechanisms for the orifice flow oscillator. For the thicker plate,
d/t = 1, the frequency increased uniformly with flow velocity suggesting
that the conventional shedding mechanism is involved, viz., the approxi-
mately constant Strouhal number shedding law observed for rigid structure
in a flow field at higher Reynolds numbers. On the other hand, for the
thinner orifice plates, d/t = 4, the tone frequencies remained constant for
increasing flow velocities, suggesting that a structural vibration may have
S
occurred in the orifice plate closing the flow oscillator feedback loop.
The envelope of the observed Strouhal numbers shown in Figure 9 indi-
cates that the smaller orifice—plate hole diameter to thickness ratios pro—
duce a wider range of possible tone frequencies than do the larger ratios.
Indeed, at d/t = 4, the orifice plates tested produced only a single tone S

or none at all over the range of test flow velocities. As the tone ampli-
tudes are also of lowest magnitude for d/t — 4, orifice—plate ratios of
d/t>4 should be utilized Ior application when noise is a factor. When
structural vibration problems are encountered due to insufficient stiff— S

ness of thin plates, perhaps countersunk orifice holes in thicker plates

could be utilized to achieve quiet operation.
S

The different velocity dependences of the broadband radiated noise

-
~~ shown in Figure 11 indicate that any of the three fundamental noise gener-
ation mechanisms can dominate. The parameters controlling which source
H mechanism dominates are yet to be determined . Measurement of the radiation
patterns for the orifice—plate noise would indicate whether the source S

mechanism was omnidirectional and hence that of a monopole or that asso—

55

ciated with a higher order source. Detailed velocity field measurements

5

inside the orifice opening would also be useful in defining the noise
source mechanism .

24

~.
IL 555 555 -
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ -.‘~~~~~~ ~~~~~~~~~~~~
____ 55 -55_~S -555-55_S 55

~~~~~~~~~~~~~~~~~~~ -5-55-555- -— ~~~S-5~~ -55--5-5

S -5~-5~~~
5
..
~~~~~~— w --~~-~~~~~~-.
w .. s.c
, .
,.-- -~~
~~~~~

The maximum radiated broadband noise levels were shown in Figure 12

to collapse for both the single and 31 hole orifice plates on the exit jet
dynamic pressure (determined by the center orifice exit velocity U )and
e
the total open area of the orifice plates. This indicates that the flow
fluctuations in each orifice opening may act, for example, as a small vi-
brating piston, each contributing independently to the radiated sound level
S
at the field point. The radiated noise was found to be greatest when
d/t — 1 for both the tonal and broadband noise.
The mean velocity field profiles shown in Figure 14 indicate that the
mean flow field of a given orifice is disturbed by the presence of adjacent
jets. This did not seem to be a significant factor in the broadband noise
production process, however, due to the success of the normalization of
noise data for 1 and 31 holes shown in Figure 12. There also appeared to
be no unique differences in the spectral features of the radiated noise
from the single or multiholed orifice plates. Hence, these results tend
S to minimize the significance of interaction effects in the broadband or
tonal noise producing mechanisms.
The radiated tones were found to be associated with strong periodic
fluctuations in the jet mixing layers (see Figure 15). It was observed
that the introduction of a pencil point at a critical location in the jet

S
flow field within one or two diameters of the orifice could eliminate the
tone. More detailed experiments to determine the fluctuating flow features
inside and downstream of the orifice are needed to clarify these important
aspects of the tone generation (and elimination) mechanisms.
S

CONCLUSIONS
1. The velocity dependence of broadband noise levels radiated from
subsonic airflow through single and multTholed orifice plates varies
4 8
between U~ to U~ .
2. Maximum tone and broadband radiated noise levels occur when
d/t — l. S

3. The range of Strouhal numbers for tones radiated by single and

S inultiholed orifice plates decreases with increasing d/t.
4. Acoustic tone onset significantly increases the jet radiated
broadband noise levels.

25

S
—- .5— _ -_.__ - S55~~~~ s~ .-5s s- 5S- 5 0 w 5 5 - er -a-— 55

-----S — L ______ ______ ____ -

-5 ~~~~~~~~ ~~~~~~~~~~~~~~~~~~~
 -

5. Tone generation is associated with stationary waves in the jet

mixing layer velocity field.
6. Small beveling of the edges of the orifice holes reduces the
levels of the broadband and tonal components of the radiated noise by
2—4 dB.

RECOMMENDATIONS
The following aspects of orifice flow noise are recommended for fur-
ther study.
1. Conduct simultaneous measurements of the tone pressure field and
S S
~

the fluctuating velocity field inside and downstream of the orifice

openings.
2. Conduct flow visualization studies utilizing smoke and high—speed
strobscopic photographic techniques synchronized with the tone pressure
field to determine the features of the orifice—jet stationary waves.
3. Experimentally determine the effects of rounded orifice inlets
and “scalloped” downstream orifice—hole edges on the tonal and broadband
noise levels. The reduction of the correlation length of the ring vortices 55

shed from the orifices could significantly reduce tonal noise levels. S

4. Measure the orifice—plate acceleration levels to determine if

structural oscillations play a role in closing the feedback loop in tonal
noise production.
5. Build an anechoic chamber around the test region and measure the
radiation patterns of the orifice—plate noise to determine whether
monopole, dipole, or quadrupole noise sources mechanisms dominate.

ACKNOWLEDGMENTS
The authors wish to thank Drs. Alan Powell and William Blake for their 55

helpful suggestions in the interpretation of the data and the planning of

S

new measurements.

26
S - S 5-S_~~~~~~~~ S

~~~~~~ ~~
5-
V
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _—
_ -
— — -5.---— — -~~~ --——
S. S
S S
- 5
. I•
~~5
- 5 55
~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
5~~~ ~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -55-— --
S S
555
 _____ — -5 .5-55.555 -5 -

.5
5 .‘ - REFERENCES
1. Anderson, A.B.C., “Dependence of Pfeifenton (Pipe Tone) Frequency
on Pipe Length, Orifice Diameter, and Gas Discharge Pressure,” J. Acous.
S

Soc. Am. , Vol. 24, No. 6, pp. 675—681 (Nov 1952). 55

2. Anderson, A.B.C., “Dependence of the Primary Pfeifenton (Pipe

Tone) Frequency on Pipe—Orifice Geometry,” J. Acous. Soc. Am., Vol. 25,
No. 3, pp. 541—545 (May 1953).

3. Anderson, A.B.C., “A Circular—Orifice Number Describing Depen-

dency of Primary Pfeifenton Frequency in Differential Pressure, Gas Den-
sity , and Orifice Geometry,” J. Acous. Soc. Am., Vol. 25, No. 4, pp.
626—631 (Jul 1953).

4. Anderson, A.B.C., “A Jet—Tone Orifice Number for Orifices of

Small Thickness—Diameter Ratio,” J. Acous. Soc. Am., Vol. 26, No. 1,
pp. 21—25 (Jan 1954).

5. Anderson, A.B.C., “Metastable Jet—Tone States of Jets from Sharp—

Edged , Circular, Pipe—Like Orifices,” J. Acous . Soc. Am., Vol. 27, No. 1
(Jan 1955).

6. Anderson, A.B.C., “Structure and Velocity of the Periodic Vortex—

Ring Flow Pattern of a Primary Pfeifenton (Pipe Tone) Jet ,” J. Acous. Soc.
Am., Vol. 27, No. 6 (Nov 1955). -

7. Anderson, A.B .C., “Vortex Ring Structure—Transition in a Jet

Emitting Discrete Acoustic Frequencies,” J. Acous . Soc. Am., Vol. 28,
No. 5 (Sep 1956).

8. Curie, N., “The Mechanics of Edge—Tones,” Proc. Royal Soc.,

55
Vol. 216, Ser. A , pp. 412—424 (1953).
55

9. Powell, A., “On the Edge Tone,” J. Acous. Soc. Am., Vol. 33,
No. 4, pp. 395—409 (Apr 1961).

10. Chanaud, R.C. and A. Powell, “Some Experiments concerning the

Hole and Ring Tone,” 3. Acous. Soc. Am., Vol. 37, No. 5, pp. 902—911
--
(May 1965).

27

-‘I
—55 -— 5- -—S --.-~~~~~~~ -~~~~~~~~ S-~~~~~
~~~~~~~~ --~~~~~ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
S 5— S S- —- 5-
55
~~~~~~~
~~~S-555 ~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~ 55 5555555
-S55S------— ~- — ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~5
55
~
_____________
~~~~~~~~
I—’—- - ~~~~~~
~ ~ ~~~ 5- ~~~~~~~~~~S-5--S 5--5~~~

SS
.5
S]
r

11. Elder, S.A., “Self—excited Depth Mode Resonance for a Wall—

Mounted Cavity in Turbulent Flow,” J. Acous. Soc. Am., 64(3), pp. 877—890
(Sep 1978).

12. Bechert, D. et al., “Experiments on the Transmission of Sound

S
5 Through Jets,” Paper No. 77—1278, American Institute of Aeronautics and
Astronautics Fourth Aeroacoustics Conference, Atlanta, Georgia (3—5 Oct
1977).
5

13. Bechert, D. and E. Pfizenmaier , “On the Amplification of Broad— S

band Jet Noise by a Pure Tone Excitation,” J. Sound and Vibration, 43(3),
pp. 581—587 (1915).

14. Iudin , E.Ia., “The Acoustic Power of the Noise Created by Air— S

duct Elements,” Soviet Physics Acoustics , Vol. 1, pp. 383—398 (1955).

5
15. Westley , R. and G.M. Lilley, “An Investigation of the Noise Field
from a Small Jet and Methods for its Reduction,” The College of Aeronautics,
Cranfield England Report 53 (Jan 1952).

16. Hubbard , H.H. and L.W. Lassiter, “Experimental Studies of Jet

Noise,” J. Acous. Soc. Am., Vol. 25, No. 3 (May 1953).

17. Lush, P.A., “Measurement of Subsonic Jet Noise and Comparison

with Theory,” J. Fluid Mech., Vol. 46, Pt. 3, pp. 477—500 (1971). -

18. AGARD Conference Proceedings No. 131 on Noise Mechanisms, -

Brussels, Belgium, 19—21 (Sep 1973).

19. Ffowcs Williams, J.E., “Aerodynamic Noise,” American Institute

of Aeronautics and Astronautics Professional Study Series (1975).

20. Armstrong, R.R. and A. Michalke, “Coherent Structures in Jet Tur-

bulence and Noise,” American Institute of Aeronautics and Astronautics S
5
Jour., Vol. 15, No. 7, pp. 1011—1017 (Jul 1977).

21. Beranek, L.L., “Noise and Vibration Control,” McGraw—Hill (1971).

22. Chen, S.S., “Vibration of a Row of Circular Cylinders in a

Liquid,” Transactions of American Society of Mechanical Engineers, pp.
1212—1218 (Nov 1975).

28
L

L 5 _ _

—— —
_ _ _ _ _ _ _
- 55 — - 5 r —. .
~~~~ _ _ _ _ _ _ _ _
5 5— _ _ _ _ ~~~
—
~~55-55-5S -~ -~~~~~
—55 ..~~~ -5 ~~~~~~~~~~ S.S~-5~5 .5.5-555. S~~~~~~ .
~~~~~~~~~~~~~~~~ 1s~ 555~~~~~ .q 1
. ~
 ~~~

23. Stowell, E.Z. and A.F. Deming , “Vortex Noise from Rotating Cylin-
drical Rods ,” NACA Tech Note 519, Washington (Feb 1935).

24. Phillips, O.M., “The Intensity of Aeolian Tones,” J. Fluid Mech.,

pp. 607—624 (1956).

25. Tatsumi, T. and T. Kakutani, “The Stability of a Two—Dimensional

Lam inar Jet,” J. Fluid Mech., 4, pp. 261—275 (1958).

26. Sato, H., “The Stability and Transition of a Two—Dimensional

Jet,” J. Fluid Mech., Vol. 7, Part 1, pp. 53—80 (1960).
S

27. Davies, P.O.A.L. et al., “The Characteristics of the Turbulence

in the Mixing Region of a Round Jet,” J. Fluid Mech., 15, pp. 337—367
(1963).

28. Kolpin , M.A., “The Flow in the M ix ing Reg ion of a Je t,” J. Fluid
Mech., 18, pp. 529—548 (1964) .

29. Bradshaw, P. et al., “Turbulence in the Noise—Producing Region

of a C irc ular Je t,” J. Fluid Mach., 19 , pp. 591—624 (1964). —
30. Sato, H. and F. Sakao, “An Experimental Investigation of the
Instability of a Two—Dimensional Jet at Low Reynolds Numbers,” J. Fluid
Mech., Vol. 20, Part. 2, pp. 331—352 (1964).

31. Becker, H.A. and T.A. Massaro, “Vortex Evolution in a Round Jet,”
J. Fluid Mech., Vol. 31, Par t 3 , pp. 435—448 (1968).

5
32. Beavers, G.S . and T.A. Wilson, “Vortex Growth in Jets,” J. Fluid
Mech., Vol. 44, Par t 1, pp. 97—112 (1970) .

33. Crow, S.C. and F.H. Champagne, “Orderly Structure in Jet Turbu—
lance,” J. Fluid Mech., Vol. 48, Part 3, pp. 547—591 (1971).

34. Law , J.C. and M .J . Fisher , “The Vortex—Street Structure of

‘Turbulent’ Jets, Part 1,” J. Fluid Mach., Vol. 67, Part 2, pp. 299—337
(1975). 5

S
-
- -

~~~~~~~~~ 55-5~~5_-5 S
- _ _ ---
~~~~~~~~~~~~~~~~~~ - S . S- ~~~~~~~~~~ _11_

5 555-555-5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .5~~S - 5~ s :S.5~~ S 5-555.55 -5S~~5--5

_.
~~~~~~~~~~~~~~~~~~~~~~~~~
:
_ ~~~~~~~ ~~~~~~~~~~~~~~~~~~~~
,~ ss~~~~~~~~~~ 5
‘
 S
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
-
55. 5555 5
~~~~
55 5_S S
~ 5.
~~~ ----- ~~S
55

—S
.s ‘~~~~~~~~
5 - T 5 5
S ~~~~~
55
5- s
~~~~~~w5-s
r. T55’
.
~~ ~~~
5 ..
,S~_ _ SS5 S __.5S_~~_ 5555 _.~S _ _ _ _ - 5 ~~~~~~ ~~~~~__.55SS S,_~~~

5
5
5__55~S~
,
.5— 5 5— 5
———— - —.—- -SSS-S-—.--—5 5555 5-5 5

35. Curle, N., “The Influence of Solid Boundaries upon Aerodynamic

Sound ,” Proc. Royal Soc., London, Series A , Vol. 23, pp. 505—514 (1955).
S
36. Kovassnay , L.S.G., “Hot—Wire Investigation of the Wake Behind
Cylinders at Low Reynolds Numbers,” Proc. Royal Soc. A ., 198, pp. 174—190
(1949).

30

-
S

S ~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -- 5
~~~~~~~~~~~ ~~~~~~~~~ T~~~~S .
 - -

S
INITIAL DISTRIBUTION

Copies Copies
S

1 DDR&E/Info Of f, Lib Br 4 SEA 081/V . Engel

2 SEA 08E/S. Dom
2 CHONR 1 SEA 924N/J. Fuchs
1 H. Fitzpatrick S

1 Tech Lib 1 NAVSEC

2 CHNAVMAT 3 NAVUSYSCEN NLONLAB

1 Dir , Lab Programs 1 P. Bakewell
NMAT 03L 1 11. S chloemer
1 Lab Management Div 1 W. Strawderman
NMAT 035
1 NBS/Tech Lib S

2 NRL
1 Dr. Hansen 3 BUSTAND
1 Tech Lib 1 P . Kiebanoff
1 G. Schubauer
1 ONR/Boston 1 E. Magrab

1 ONR/Chicago 12 DDC

1 ONR/New York 1 Louisiana State Univ

R. Hussey
1 ONR/Pasadena
1 MIT/P . Leehey
1 ONR/San Francisco
1 VPI/Dr. D.P. Telionis
4 USNA
1 Dr. S. Elder 1 Univ of Michigan/W . Willmarth
1 Dr. B. Johnson
1 Dr. M . McCormick 1 Univ of Minnesota/J. Killen
1 Tech Lib
1 Pennsylvania State Univ
1 NAVPGSCOL , Monterey , CA E. Skudrzyk, G. Lauchle

2 NOSC 1 Univ of Rhode Island

F. White
1 NOSC 4543/J.M. ILoltzmann
10 John F. Kennedy Space Center
1 NSWC , White Oak VE—FSD—22/M .F. Matis

1 NUSC , Newport 1 Hersh Acoustical Engineerii~,

Chatsworth, CA
55

1 NAVUSEACEN 6005
1 Binary Systems/S. Gardner
10 NAVSEA
1 SEA O3C
1 SEA O37
1 SEA 0372/A. Paladino

1
31

S t iir irw - ~~~~~~~~~~~~~~~~~~~~~~

S

- - - ----
— — —.-~ --— ~~ -— -
~-——— ~ - ~~~ ~~~~~~~~~~~~ ~~~~
~~~~~~~~~~~~~~~~~~~~~~~
 555 5 _____
- -
_ _ _ _ _ _
- — -

Copies Copies Code Name

3 Bolt Beranek & Newman , 1 1902 Dr. G. Maidanik
Cambr idge
1 J. Barger 1 1903 Dr. G . Chertock
1 K. Chandiramani 1 192 R . Biancardi
1 D. Chase
1 1932 J. O’Donnell
2 Bolt Beranek & Newman , 1. 1933 J. Lee
California/A. Piersol
J. Wilby 1 1942 W .K. Blake
1 1942 B.E. Bowers
3 Catholic Univ of America 1 1942 R.W. Brown
1 F. Andrews 1 1942 L.S. Chandler
1 Y.C. whang 1 1942 T.M. Parabee
1 J. Clark 1 1942 K.A . Lewis
1 1942 F. Hwang
1 Bendix Elec trodynamics Div 1 1942 F.E. Geib , Jr.
R. Sherwood 1 1942 T.C. Mathews
1 1942 M.J. Casarella
1 1942 L. Cole
CENTER DISTRIBUTION 1 1942 L. Gordon
1 1942 P. Granum
Copies Code Name 1 1942 D. Paladino
20 1942 F.C. DeMetz
1 01 Dr. A. Powell 10 1942 R.S. Langley
1 01 Dr. D. Jewell 10 1942 J. Wilson
1 1942 R. Armstrong
1 15 W Cummins 1 1942 L. Maga
1 1942 J.L. Clatterbuck
1 1503 V .P. Brownell
1 1503 R. Dart 1 196 D. Feit
1 196 Dr. W .T. Reader
1 1508 F.B. Peterson
1 1965 Dr. M.L. Rumerman
1 1524 W.C . Lin
1 154 W . Morgan 1 27 Dr. R . Allen

1 1541 P. Granville 1 2743 R. Schoeller

1 1544 R. Cumming 10 5211.1 Reports Distribution

1 1552 T. Brockett 1 522.1 Library (C)
1 1552 J. McCarthy
1 1552 J. Power 1 522.2 Library (A)
1 1552 Dr. T.T. Huang 1 5231 Office Services
1 1552 N. Santelli
1 1556 C. Santore
1 1556 M. Jeff era

1. 19 Dr. M . Sevik
1 1901 Dr. M. Strasberg

32

~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ~ SS S

55 -

Sc

DTNSRDC ISSUES THREE TYPES OF REPORTS

1. DTNSRDC REPORTS, A FORMA L SERIES, CONTAIN INFORMATION OF PERMANENT TECH.
S
NICA L VALUE. THEY CARRY A CONSECUTIVE NUMERICA L IDENTIFICATION REGARDLESS OF
THEIR CLA SSIFICATION OR THE ORIGINATING DEPARTMENT.

2. DEPARTMENTAL REPORTS, A SEMIFORMAL SERIES, CONTAIN INFORMATION OF A PRELIM-

INARY , TEMPORARY , OR PROPRIETARY NATURE OR OF LIMITED INTEREST OR SIGNIFICANCE.
S
THEY CARRY A DEPARTMENTAL ALPHANUMERICAL IDENTIFICATION.
5
3. TECHNICAL MEMORANDA .AN INFORMAL SERIES .CONTAIN TECHNICA L DOCUMENTATION S

-
‘
OF LIMITED USE AND INTEREST . THEY ARE PRIMARILY WORKING PAPERS INTENDED FOR IN-
TERNAL USE. THEY CARRY AN IDENTIFYING NUMBER WHICH INDICATES THEIR TYPE AND THE
NUMERICA L CODE OF THE ORIGINATING DEPARTMENT. ANY DISTRIBUTION OUTSIDE DTNSRDC
MUST BE APPROVED BY THE HEAD OF THE ORIGINATING DEPARTMENT ON A CASE-BY-CASE
BASIS.

5-555

~~~~~~~~~~~~~~~~
-555555 ~ 5~~~~S555_
5 ~- - 5 5 5 5 5 5 555 S. 5_

- _ _ _ _

_______ 55 &
— — ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -S ~~5.5SS-5~ ________ - ~~~~~~~~~ ~~~~~~~~~~~~~ -~