An experimental investigation was conducted to determine the penetration of air jets d.irected perpendicularlY to an air stream. Jets Issuing from circular, square, and. elliptical orifices were investigated. and. the jet penetration at a position downstream of the orifice was determined- as a function of jet density, jet velocity, air-stream d.enaity, air-stream velocity, effective jet diameter, and. orifice flow coeffIcient. The jet penetrations were determined for nearly constant values of air-stream density at three tunnel-air velocities arid for a large range of Jet velocities and. densities. The results were correlated in terms of dimensionless parameters and the penetrations of the various shapes were compared. Greater penetration was obtained. with the square orifices and the elliptical orifices having an axis ratio of 4:1 at low tunnel-air velocities and low jet pressures than for the other orifices investigated. The square orifices gave the best penetrations at the higher values of tunnel-air velocity and jet total pressure

Bowden, Dean T.

Callaghan, Edmund E.

Ruggeri, Robert S.

English

NASA Technical Reports Server

* >.
TECHNICAL NOTE 2019
PENETRATION OF NR JETS ISSUING FROM CIRCULAR SQUARE, AND
ELLIPTICAL ORIFICES DIRECTED PERPENDICUIJ3RLY
TO AN AIR STREAM
By Robert S. Ruggeri, Edmund E. Callaghan
and Dean T. Bowden
Lewis Flight Propulsion Laboratory
Clevelaxd, Ohio
.
Washington
February 1950
.
.6
.-
https://ntrs.nasa.gov/search.jsp?R=19810068719 2020-03-21T11:48:31+00:00Z
TECH LIBRARY KAFB, NM e
&
i
NATIONALADVISORYCOMMITTEEFOR AERONAUTICS
TECHNIOALNom2019
HZNEI’RATIONOF AIR JETS ISSUINGFRCM CIRCULAR,EXJUARE,AND
EIUPTICAL ORIFICESDIRECTEDPEKPENDICUMRLY
TO ANAIRSTREAM
By RobertS. Ruggeri,EdmundE. Callaghan
and Dean T. Bowden
smy
An experimmtalinvestigationwas oonduotedto determinethe
penetrationof air jetsdireotedperpendiouhmlyto an air stream.
Jets issuingfrom Ciroub.rj ww=s ati f=~i@~o~ Ofiices ==
investigatedand the jet penetrationat a positiondownstream
of the orifioewas determinedas a functionof jetdensity,jet
velooity,air-streamdensity,air-streamvelooity,effeotivejet
diameter,and orificeflow coefficient.The jet penetrations
were determinedfor nearlyconstantvaluesof air-streamdensity “
at threetunnel-airvelocitiesand for a largerange of jet vel-
ooitiesand densities. The resultswere correlatedin tams of
dimensionlessparametersand the penetrationsof the variousshapes
were mlllparea.
Greaterpenetrationwas obtainedwith the squareorificesand
the ellipticalorifioes havingan axis ratioof 4:1 at low tunnel-
air velocitiesand low jet pressuresthan for the otherorifices
investigated.The squareorificesgavethe best penetrationsat
the highervaluesof tunnel-airvelocityafi jettotalpressure.
INTRODUCTION
A oiroular:et directedperpeniiimkrlyto an air streamcan
be satisfactorilyutilizedas a means of heatingor ooolingan air
stream(reference1). A laterinvestigation(reference2) showed
that squareand ellipticalorificesgive higherflow coefficients
than circularorifices. Betterpenetrationsmightthereforebe
obtainedwith orifioeshapesotherthan ciroles. In aaaition, a
largevariationof flow coefficientwith jet-pressure ratio was
observed in the investigationreportedin reference2. Xt is
possiblethatbettercorrelationof the data of reference1 cti-d
be obtainedby includingthe flow coefficientin the analysisof
the data presented.therein.
2 NACA TN 2019
An investigationto determinethe penetrationof air jets
issuingfromoiroular,square,and ellipticalorifioeswas under-
takenin a 2- by 20-inch-duettunnel at the NACALewislaboratory,
and a studyof the effectof variationsin the orificeflow coef-
ficienton the correlationof the experimentaldatawas made. The
jet penetrationat a fixedpositiondowndxeam of the orificeswas
determinedat tunnel-airvelocitiesof 160,275, and 380 feet per
seoondfor circular,square,and elliptical.orificea.Each orifice
was investigatedovera rangeof pressureratiosfrom1.15 to 3.2
and at a jet totaltemperatureof approximately400°F.
APPARATrJsAND PROCEDURE
The orificesinvestigatedconsistedof threecircles,two
squares,two ellipseswith an axis ratioof 4:1,and two ellipses
with an &XiS ratioof 2:1. The oircularorificeshad diametersof
0.375,0.500Jand 0.625inch;the squaresand the ellipseshad
areasequivalentto the 0.375-and 0.625-inch-diametercircles.
For theseinvestigations,the elliptical.orificesweremountedwith
the majorwis parallelto the air streamand the squareorifices
with two edgesparallelto the air stream. A boundary-layerbypass
was employedin orderto minimizethe effectof tunnelboundary
layer. Air for the jetswas obtainedby passinghigh-pressureair
throughan electricheaterand intoa plenumchamber,the upp?r
wall of whichcontainedthe orifices(fig.1).
Each orificewas investigatedovera rangeof orifice-pressure
ratiosfrom 1.15to 3.2 for a jettotaltemperatureof approximately
400°F, and at tunnel-airvelocitiesof 160, 275,and 380 feetper
second. The penetrationof each jetwas measuredat the farthest
positiondownstreamof the orifioecenterline (18.88in.)witha7
rake consistingof 22 thermocoupleprobesspaced; inchapart.
Staticpressureswere measuredin the planeof the orificeand at
a pointupstreamof the orificeby pressuretaps in the tunnelwall.
c
Dj
2
.
SYM60LS
The followingsymbolsme used in this report:
flow coefficient,ratio of measured to theoreticalflow
diamter of circularjet orifice,feet
depthof jet penetrationintoair streamat distance s
downstreamof orificecenterline,feet
r
.
e
<’
.. NACA TN 2019 3
4
-k
.
@xing distanceor distancea~tre= of orificecenter
line,feet
velocltyof jetat vena contracta,feet per %eoond
velocityof free stream,feet per second
dud width,feet
viscosityof jetat venacontracta,
viscosityof free-streamair, slugs
slugsper foot-second
per foot-second
mass density of Jetat vena contracta,slugspr oubicfoot
mass densityof free-streamair, slugsper cubicfoot
RESULTSANDDISOUSSIOI?
The analysisof referenoe1 indioatesthat the penetration
coefficient Z/Dj can be correlatedin termsof the JetReynolds
number (PjVjDj)/PjJthe velocityratio Vj/Vo, the densityratio
P#PoY the viscosityratio Pj/~, the mtiingdistance-deter
ratio S/Dj, and the tiath,coefficientwbj. Depth of penetra-
tion definedin reference1 as the pointat whichthe temperature
6is 1 F abovethe free-streamtotaltemperature,waa obtainedfrcan
the temperatureprofilesmeasuredat the thermocouplerake.
The primaryfaotorsin the correlationof the penetrationdata
are densityratio,velocityratio,and mixingdistance-dismeter
ratiosas indicateaby the resultsof reference1. The effectof
the otherparameterswas not evidentbecauseno consistenttrends
couldbe observedin the data. Appreciableover-allsoatterof the
data,however,indioatedthatnot all the necessaryvariableswere
includedin the analysis. The analysisof reference1 acesnot
includean effectof jetMach nuniher,that is, pressureratio. T@
scatterevidentin re~erenoe1 may be ~sed in partby the vari-
ationof flow coefficientwith pnssure ratioshownin refe~nce 2.
In additionto the effectof jetMaohnwiber on the flow coefficient
noted in referenoe2, a mall effeotof JetReynolds@er on the
flow coefficientwas observedas well as a smalleffectofwitith
coefficienton the jet flow.
.4 NACA TN 2019
The inolusi.onof’the flow coefficientin the analysismight
eliminatemuch of the data scatteralreadydisoussedby including
in part someeffeotof jetMaoh number,jetReynoldsnumber,and
widthcoefficient.Beoausethe flow ooeffioientis the ratioof
the actualflowto the theoreticalflow,it may alEIobe considered
as a ratioof the effectivejetareato the gecxnetricorifioearea.
The effeotivejetdiameteris thereforerelatedto the geometrio
diameterby the squareroot of the flow coeffi.oient.
In orderto investigatethe effectof flow coefficienton
the data oorrel.ation,a plot similarto that in nference 1 was
made of the penetrationcoefficientas a functionof the product
of the densityratio,the velooityratio,and the squazwroot of
the mixingdistance-disneterratio (fig.2). The flow coefficients
were then calculatedby the methcdspresentedin referenoe2 and
the data in figure2 were replotted(fig.3), with the effective
Jet diameter~ Dj replacingthe actualjetdiameter Dj in the
parameters.A comparisonof figures2 and 3 indicatesthat the
scatterhas been reduoedby usingthe flowcoefficientin the cor-
relation. It is thereforeevidentthatthe correlationis improved
when the aotualJet dimeter is replaoedby the effeotfvejet dia-
meter. Hereinafterthe penetrationcoefficientand mixingdistanu-
dhmeter ratioare basedon the effectivejetdiameterand are
redefinedas 2/@Dj, and s/@Dj, respectively. +
The analysisof the penetrationobtained.with the square
orificeswas oonductedin a mannersimilarto that employedfor 4
circularorifices.The penetrationcoefficientwas firstplotted
as a functionof’the productof the densityratioand the velocity
ratio. For eaoh squareorifice,the penetrationco@’ficientwas
basedon the diameterof the equivalent-areacircleand in both
casessinglecurveswere obtained.Becausethe two ourvesfor the
squareorificeswere similarto thoseobtainedfor the circlesof
the samearea,the penetrationcoefficientsfor both squareorifices
were plottedas a functionof the prcductof the densityratio}
the velocityratio,and the squareroot of the mixingdistance-
diameterratio (fig.4); as for the oircular-orifioedata,a single
curvewas obtained.A,comparisonof figures3 and 4 showsthat
slightlyhigherpenetrationcoefficientswer~ o%tainedwith squsn
orificesthanwith circularorifices.
A similarprocedurewas firstemployedin the correlationof
the data obtainedwith the elliytioalorifioes. A plotwas tie of
the penetrationcoefficientas a funotionof the produotof the
densityratioand the velooftyratiousinga penetratichcoefficient
based on the equivalent-areacircle. Resultsobtainedwith the
ellipsehavingan axis ratioof 4:1 and-anarea equivalentto a
.-
NACA TN 2019 5
‘i
.
0.375-inch-diametercircleare shownin figure5. Three separate
curvesdependenton the tunnel-airvelocitywere obtaine~. Further
analysisof thesedata showedthat correlationoouldbe obtained
providedthe penetmtion coefficientwas plottedas a functionof
the prduct of the densityratioand the squareof the velocity
ratio,as shownin figure6. The data for the O.625-inchequivalent-
diameterellipsewith an axis mtio of 4:1 were then plotteain
termsof the same parametersand againa singlecurvewas obtainea
(fig.6). (comparisonshowsthat the curvesin figure6 are separated
by a funotionof the equivalentCliemeter.Becauseof the shapeof
the curvesat the l-r values of the parameterand becausethey
becomeapproximatelyparsllelat the highervaluesof the parameter,
it is not possibleto correlatethe data for both ellipsesin terms
of the ratioof mixing aistance b diemeter=a obtaina single
curve. It shouldbe yossible,however,to interpolatebetween
the two curvesana obtainvaluesat otierratiosof mixing&is-
tanceto diamet@? S/D~a
In the analysisof data for the elliyseswithan axisratio
of 2:1, the pmced.urefollouedwas similarto that employeawith
the ellipseshavingan axis ratioof 4:1. Zn order to correlate
the penetrationcoeffioientsat all tunnel-airvelocitie~,the
penetrationooeffioientwas @Ottea as a functionof the produotuf
the CLensityratioend the velocityratioraiseato the 1.5 power.
Use of thisparametermaae possiblethe correlationof the data for
the el.liyseswith an axis ratio of 2:1 (fig.7). As for the ellip-
ses havingan axis ~tio of 4:lJthe natureof the curvesprecludes
furthercorrelationin termsof the ratioof mixingdistanceto
diameterand againit is necessaryto interpolatebetweenthe curves
to obtainvaluesat otherratiosof mixingdistanceto diameter.
A studyof the parametersrequ~redfor correlatingthe data of
the cirulesana the ellipseswith axisratiosof 2:1 and 4:1 showed
that the powerto whichthe velocityratiowas =isea increased
with increasingexis ratio. Velocity-ratioexponentis shownas a
functionof =is ratioin figure8. The curve indicates that the
rate of increaseof the velocity-ratioexponent~ecreasedwith
hneasing -s ratio. Furtherstudyof figure8 indtcatestha% an
ellipseturnedat rightanglesto the air streammay require
exponentsless than 1.0 becausethe effectiveaspectratiowith
respectto the air stre~ is lessthan 1.0.
Bemuse boundary-layeremovalwas employedthroughoutthe
investigation,the effectof boundary-layerthicknesson jet penetra-
tionwas not &etermine&.From the correlationof the dkta,however,
the effecta~ars to be small. The ~ow momentumof the boundsmy
layerenablesthe high-velmity$etto penetratethe layeralmost
6 NACA TN 2019
unaffected.Eenue,a verythiokboundarylayermightadd slightly
to the penetrationbecausethe jet is fartherfrcmthe surface
when it entersthe free streamof highmomentum.
Becausethe ellipses do not correlatein termsof the same
parametersused for the cirolesand the squares,no directccmpri-
son of all the shapesoan be obtained,exoeptfor specifiovalues
of Jet totalpressure,jettotaltemperature,tunnel-airveloclty,
and tunneltotalpressure.
The celoulatedpenetntion of the four shapesat assumed
tunnel-airvelocitiesof 150, 250,ati 350 feetpm seocmdas a
funotiunof set totalpn=ssureis shownin figures9(a),9(b),and
9(0],respectively.These ourveswere caloul.atedusingthe ourves
of figures3, 4, 6, and 7 and assuminga free-strea totalpressure
of 29.92inchesof meroury,a free-streamtotaltem~rature of 59° F,
and a jet totaltemperatureof 400°F.
A studyof figure9 showsthat in generalat the low tunnel-
air velocitiesthe squqresand the ellipsesvith an axis ratioof
4:1 gavethe best penetration(fig.9(a)) and at the high tunnel-
afr velocitiesand $et pressuresthe squaresgavethe best penetra-
tions (figs.9(b)and 9(c)). In general,if the speoifiuconditions
of jet totalpressure$jettotaltemperature,air-streamvelooity$
and air-streamtotalpressureare known,it is best to caloulate
the necessary parametersand to comparethe penetrationmeffici.etis
beforeseleotinga particularorificeshape.
SUMMARYOF RIWLTS
The followingresultswere obtainedfroman investigationto
determinethe penetrationof air jetsissuingfromciroular,square,
and ellipticalorifioesdirmted perpendicularlyto an air stream!
1. The use of the flow meffloientto obtainan effeotivejet
diameterprovidedbettercorrelationof the penetrationcceffioients
of oiroularorificesin termsof the usual.parametersof density
ratio,velooityratlo$and mixingdistanoe-diameterratio.
2. The penetrationcoeffioient~obtainedwith square orifioes
could be correlatedwith the sameparameterused for the circles,
providedthat a
area cirdlewas
jet dimensioneq~ to the diameterof the equivalent-
used.
r
L.
.
NACA TN 2019
=.
.
u
.
l
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3. It was possibleto correlatethe ellipsedata in terms
of the produotof the densityratioand the velooityratioraised
to a power. The powerto whichthe velocityratiomust be zaised
for correlationincreasedwith increasingaxisratio.
4. Greaterpenetrationswere obtainedwith squareorifices
thantith circularorificesof equalarea.
5. At low tunnelairspeedsand luw jet pressuresgreater
penetrationwas obtainedwith the squa= orificesand the
elliptical.orifioeshavingan axis ratioof 4:1 thanwith the
otherorificesinvestigated.The squareorifioesgavethe best
penetrationsat the highervaluesof
totalpressure.
Lewis31ightI’repulsionLabomtory,
IfationalA&vismy Committeefor
Cleveland,Ohio,September
tunnel-airvelooityand jet
Aeronautics,
27, 1949.
?mFImENcEs‘
1. Callaghan,EWund E., and Ruggeri.,RobetiS.: InvestU@ion
of the Penetrationof an Air Jet DirectedPerpenai-ly to
an Air Stream. NACATM 1615,1948.
I
2. (Xllaghan,EdmundE., and Bowden,Dean T.: Investigationof
FlowCoeffWLent of Circular,Square,and Elli@ioal Orifioes
at High TressureRatios. NACA TN 1947,1949.
.
NACA TN 2019
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NACA TN 2019 9
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.376 %?76
: .376 380
a ::% $%
Q .500 360
P .626 loo
.626 275
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6
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20 30 40 50 60 70
Penetrationpa~ter, pjv
=+Poo$
Hguie 2. - Variationofp;mvtraticm coeffiotent L/’Dj with penetration
P’=”’*&@ forCiroularOriricesl
10 NACA TN 2019
orifice Tunnel.
‘3 vebol
(in. ) 7(ft/seo
o 0.37!5 160
P .626 380
28 0,
24
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1I 1’1 I 1 Iaw”l I I I I I --l16 llll&@lll 111111I I I I[ I I I 1 I I
1.2
8
/~
f
4 It
/’
/
/
o 10 20 30 40 60 60 70
TPjvj sPenetrattanparameter,~Poomj
Figure3. - Variation of penetrationoeffiolentL/@ D~ withpenetratlam
paramtep PJVJ s
F
forohoularorifices.
~ CD,
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s.
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NACA TN 2019
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“1%Orlfiaeequivalentdiameter(in.)Q 0.375.375: .375: .625.6259 .626
-- I II
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air
velooitT(ft/sec
160
275
380
160
275
360
m
24 -
20
16
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8-
/
/
f
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//
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0 10 20 30 40 50 60
Figure4. . Variationofpem?tratloncoefficientZ~ D$ with
r
PJvj spenetrationparameter— — forsqpareorlfioese
Povo @Dj
II
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12 NACA TN 20(9
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-=%=
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“
o 2 4 pjv$ 6 8 10
x
Povo
-.
FigureS. - Variationof penetrationcoefficient2\fiDj with
&
‘jv~ for ().375.in~equivalentdlameter ellipse with an axis
Povo
ratio of 4:1. Ratio of mixingdfstanceto diameter s\Dj,50.3.
NACA TN 2019
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Orf.floeTunnel- Ratio of
equlmlent air mixing
diameter veloai
7
distanceto
(in.) (ft/seo diameter
s/Dj
o 0.375 160 50.3
.375 275
:
50.3
.375 60.3
.625 160 30.2
; .625 275 30.2
l625 380 30.2
28
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F%gure 6. . Vuiatlon of penetrathn Rfzloient l/!D~ with ~~<)2 for
0.375. ma 0.625dneh equivalent-dismterellipseswith euisratiosof 4:1.
13
—.
—
—
NACA TN 2019
—— .. ..-... —
Ormbe Tunm3L Ratio of
equivalent air mixing
diamtie~ velooLt Matance to
(in.) (i%/a8,0~diameter
B/Dj
o 0.375 160 50.3
.375 275 50.3 ,..—
: l375
.—.—
380 50.3
.625 180 30.2
; .62S 275 30.2
0 .625 580 30.2
28 t
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Figure7. .
(d
Variation of penet~tion aoeffhtent t/.. Dj with ~ v
ror 0.375-ard 0.625-inoh
Or 2:1~
eqplvalent-dia.meterelllpaeswithaxU5-miiios
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NACA TN 2019 15
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lHgure 8. - Variation of velO&ty=-y::o qonent with increasing
16 NACA TN 20[9
Orifice diameter or
equivalent diameter
.
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3 - ——— Elliptical; axis
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—-—- Elliptical; axis
rat,ioof 4tl
=&=
2.
30 40 50 60 70 80 90
Jet total pressure, in. Hg absolute
(a) Tunnel-air velocity, 150 feet per second.
Figure 9. - Variation of penetration with jet total pressure for
various orffioe shapes. Tunnel total pressure 29.92 inches of
mercury; tunnel total temperature, 59° F; Jet ktal temperature,
4000 F.
-.
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3 ‘ ——— ,EUiptical; axis
ratio of 2:1
—.— - Elliptical; axis
ratio of 4:1
T
2.
30 40 50 60 70 80 ~
Jet total pressure, In. Hg absolute
(b) Tunnel-air velocity, 250 feet per second.
Rtgure 9. - Continued. Variation of penetration with jet total
pressure for various orifice,shapes. Tunnel total pressure,
29.92 inches of mercur ; tunnel total temperature, 59° F; jet8total temperature, 400 F.
17
)
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18 NACA TN 2019
v
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9
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8 / A
Orifice diameter or ,~
equivalent diameter ,’‘
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—.— - Elliptical; axis
ratio of 4:1
I
=z$??=-
2.
30 40 50 60 70 80 9
Jet total pressure, in. Iigabsolute
(c) Tunnel-air velocity-, 350 feet per second.
Figure 9. - Concluded. Variation of penetration with jet total
pressure for various orifice shapes. Tunnel total pressure,
29,92 inches of mercur ; tunnel total temperature,
x
59° F; j%t
total temperature, 400 F.
)
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.
.
NACA-hngIq -0-20-50-125


Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream

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