1、NASA TECHNICAL NOTE NASA TN D-5467r_zt-=ZDISCHARGE COEFFICIENTS FORTHICK PLATE ORIFICES WITHAPPROACH FLOW PERPENDICULARAND INCLINED TO THE ORIFICE AXISby John E. Rohde, Hadley T. Richards,and George IV. MetgerLewis Research CenterCleveland, OhioNATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTO
2、N, D. C. OCTOBER 1969Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Report No. 2. Government Accession No. 3. Recipients Catalog No.NASA TN D-5467S.
3、 Report DateOctober 19694. Title and SubtitleDISCHARGE COEFFICIENTS FOR THICK PLATEORIFICES WITH APPROACH FLOW PERPENDICULARAND INCLINED PO THE ORIFICE AXIS6. Performing Organization Code7. Author(s) 8. Performing Organization Report No.John E. Rohde,Hadiey T. Richards, approach Machnumber; orifice
4、diameter, thickness, and inlet edge condition; orifice surface finish;interference of multiple orifices; and approach passage geometry and length. The dis-charge coefficients were found to be dependent on approaeh Math number, static pres-sure differential across the orifice, inlet edge radius on th
5、e orifice, angle between themain flow and the axis of the orifice, and the ratio of the orilice thickness to diameter.17. Key Words (S_*i_._,sted h_, Author(s)Discharge nozzle coefficientInclined orificeOrificeThick-plateUnclassified I19. Security Classif. (of this report)18, Distribution StatementU
6、nclassified - unlimited20. Security Ctassif. (of this page)Unclassified 21. No. of Pages2922. Price*$3.00*For sale by the Clearinghouse for Federal Scientific and Technical InformationSpringfield, Virginia 22151Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
7、 IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-DISCHARGE COEFFICIENTSFOR THICK PLATE ORIFICES WITH APPROACHFLOW PERPENDICULAR AND INCLINED TO THE ORIFICE AXISby John E. Rohde, Hadley T. Richards, and George W. MergerLewis Research CenterSUM
8、MARYThe flow discharged through thick plate orifices with the approaching flow perpen-dicular or inclined to the orifice axis was experimentally investigated. The study wasconducted to determine the influence of the flow and geometric parameters. The param-eters investigated were temperature and pre
9、ssure levels; orifice pressure differential;approach Mach number; orifice diameter, thickness, and inlet edge condition; orificesurface finish; interference of multiple orifices; and approach passage geometry andlength.The discharge coefficients were correlated with a velocity head parameter whichco
10、nsisted of the ratio of the velocity head of the flow through the orifice to the velocityhead of the flow approaching the orifice axis for various approach Mach numbers. Thedischarge coefficients were found to be dependent on the approach Mach number, thestatic pressure differential across the orifi
11、ce, the inlet edge radius of the orifice, theangle between the approaching flow and the axis of the orifice, and the ratio of the orificethickness to orifice diameter. The effects of temperature and pressure levels, orificesurface finish, multiple orifice interference, and approach passage geometry
12、and lengthon discharge coefficients were found to be negligible for the cases considered.INTRODUCTIONKnowledge of the flow through thick plate orifices with the approach velocity perpen-dicular or inclined to the orifice axis is required to predict the performance of someinternally cooled turbine bl
13、ades and vanes. The need for cooled turbine blades and vanesfor high performance gas-turbine aircraft engines is well recognized. In order to pro-vide cooled blades or vanes that have high heat transfer effectiveness with a minimumcoolant flow, the internal coolant passages become comparatively comp
14、lex. Thick plateProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-orifice arrangements are employedin the impingement cooling conceptwherein a highvelocity jet of cooling air is directed against the inside surfaces of a bladeor vane,Thick plate orifice
15、s may also be employedin the transfer holes usedto supply coolingair to the bladeor vane leading andtrailing edgeregions from a radial midchord pas-sage.Previous studies of orifice discharge coefficients with the approachingflow perpen-dicular to the orifice axis are reported in references 1 to 7. R
16、eferences1 and2 consid-ered perpendicular inlet flow through relatively thin plate orifices andperforated mater-ials, reference 3 perpendicular velocity on boththe inlet and exit faces of the orifice,references 4 to 6 only the perpendicular exit velocity, andreference _/perpendicularinlet velocities
17、 to rectangular holes, step louvers, andscoops.The basic conclusion of these investigations was that the flow through the orifice isinfluenced significantly by the inlet velocities perpendicular to the orifice axis and thatfor low exit velocities perpendicular to the orifice axis and high jet veloci
18、ty, the effectof exit flow velocity can be eliminated by calculation of a revised exit jet discharge pres-sure.In thick plate orifices, orifice thickness is an influential variable to the flow. Ref-erence 1 indicates the influence of the orifice thickness but the work was primarily con-cerned with t
19、hin plate orifices. The orifice flow is further influenced by the geometry ofthe main flow duct, geometry of the orifice, the flow conditions, and the proximity ofother orifices as shown in the thin plate orifice results of references 1, 3, and 7.The present investigation considered the following pa
20、rameters: temperature andpressure levels; orifice pressure differential; approach Mach number; orifice diameter,thickness, and inlet edge condition; orifice surface finish; interference of multiple ori-fices; and approach passage geometry and length. The geometry of the main flow ductin all cases bu
21、t one was a 0.25-inch (0. 063-cm) diameter tube. This tube diameter wasrepresentative of a size to be expected in a turbine blade. (The exception was a rectan-gular cross-section main duct to investigate the effect of curvature of the upstream faceof the orifice.) The orifice thickness varied from 0
22、.06 to 0.25 inch (0.15 to 0.63 cm)and the orifice diameters varied from 0.59 to 0. 128 inch (0. 150 to 0. 325 cm). The inletedge of the orifice was varied from a sharp corner to a 0. 030-inch (0. 076-cm) radius.The main duct inlet airflow Mach number was varied from 0 to 0.65, static pressure wasvar
23、ied from 20.0 to 80.0 psia (13.8 to 55.2 N/cm2), and the temperature was variedfrom ambient to approximately 1000 F (811 K). Orifices with axes at 45 and 90 anglesto the main duct flow were investigated.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,
24、-SYMBOLSAC dDdfgLMPTPRReTT TtVWXOtYPflow areadischarge coefficient, ratio of measured to ideal flow through the orificehydraulic diameter of the main ductorifice diameterfriction factorgravitational conversion factorlinear distance between the pressure tap and orificeMach numbertotal pressure in the
25、 main ductstatic pressuregas constant for airReynolds numberstatic temperaturetotal temperature in the main ductwall thicknessvelocitymeasured mass weight of flowentrance length of the main ductinclination angle or the orifice, see fig. 4specific heat ratiodensitySubscripts:main ductjet exitorificeP
26、rovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-APPARATUSA schematic diagram of the basic setup utilized for the investigation is shown infigure 1o Air at 125 psig (86.2 N/cm 2) was supplied through a filter and dryer, two pres-sure regulators in seri
27、es, a rotameter, air heater, and into the main duct of the testsection. Air leaving the main duct and collecting duct (orifice exhaust) was passedthrough throttling valves and cooling coils to an atmospheric exhaust system with the ori-fice exhaust passing through an additional rotameter. The air fl
28、ow rate through the mainduct and through the orifice and the static pressures in the main duct and orifice ductwere controlled by adjustments of both the upstream and downstream throttling valves.The air heater and dryer and the cooling coils were not in the system during the ambienttemperature runs
29、.Temperature gage_Rotameter _lPressure-,- Indicates direction To atmos )hereof airflow _I , “TemperatureRotameter _ gageJet exit static Bypass valve 7 7 Pressurepressure gage _ _3-gage_(_. Temperature I -“ F gagegage -._ ,r-125-psig Main duct static I_._ 7J_ 1 I I _Toatmosphere862-Nlcrn2)supply_ ,_
30、pressure gage-_ _ _I - _ Throttling valvesLL Pressure ,- Ambient tern- i _uL11:_ ! I _ AirCooler (for“-“ .,t U regulators “, perature ai: “uu_iilhere j _. _ , elevated tem- bypass valv _ peratures onlyl/ I r , ,L-AirOryer kFiiter _ _ i_Electric air heaterFigure 1. - Single orifice model test setup.C
31、D-IO4gI-IIDescription of ModelsOrifice geometry variations were obtained by the construction of 12 different modelsThe models were made of brass or stainless steel with the main duct or part of the mainduct formed in halves for the majority of models and joined by soft solder or brazing asshown in f
32、igure 2. This method of fabrication was employed to allow inspection of the4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_I“- Coectin9 duct!i _F-Jet staticTMainduct FBrazedor I ,_ pressure(pj)_ Isolderedjoint I_ _ , ,-Orifice_I i i _/_I,V/_,. . _
33、-_ J_-J A1,f_ PJSection A-ACD-10492-!Figure 2. - Typical single orifice model showing split construction.orifices after final machining and to permit disassembly if necessary. The models weredrilled, reamed, and polished with conventional machine tools. The orifice diameter andedge condition were ca
34、refully examined and measured with optical instruments and pluggages. Each of the standard models had a nominal upstream duct entrance length of3.5 inches (8.89 cm) and a diameter of 0.25 inch (0.63 cm), resulting in a length to diam-eter ratio of 14. This standard X/D of 14 produces fully developed
35、 flow for the turbulentflow which existed in the main duct of the models. To determine the entrance effect of thedeveloping boundary layer, one of the models was constructed so that it could be testedwith a length to diameter ratio of 2 or 14 depending on the end used as the inlet. Thismodel is show
36、n in figure 3. In addition to the models with a circular main duct, onei ,-Collecting ductI ,_-Jet statict|1 pressure (pj)Orifice_- inlet 1. li|_ . Inlet 2 _xID-_III bucisiadc XID :4 -_jl pressure (pd) = iCD-10493-11Figure 3. - Single orifice model 5 designed for two length to diameter ratios.Provid
37、ed by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-model was constructed of a rectangular duct to determine the effect of main duct curva-ture. This same model was modified after initial testing by machining a radius on theupstream orifice edge. Inspection of
38、 radius and additional testing was then carried out.Figure 4 describes model 9, which was the only model with an orifice axis inclined to themain stream. The angle a (indicated in the figure) was equal to 45 Collectingductget staticpressure (pj)7r- Main duct c Brazed or“, soldered jointsi _#_L :i I
39、L Orifice (inclined)- Duct staticpressure (pd)Section A-AFigure 4, - Inclined orifice model %CD -10494-1ISince all of the models described above were carefully made (reamed, lapped, andpolished) and inspected, it was decided to simulate a production orifice by electrical dis-charge machining orifice
40、s in a representative number of models. Four duplicate modelsfor each of two different sizes (i. e., a total of eight models) were fabricated by thisprocess.Table I identifies each of the models considered in this investigation. The table iden-tifies the models by number and summarizes the pertinent
41、 dimensional characteristicassociated with each. The accuracy in measuring the orifice diameter was :L0. 0005 inch(0. 0013 cm).6Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IABL: I. - MODEL CONFIGURATIONS INVESTIGATEI),INCI, IJI)ING PEt(TINENT DIM
42、t:NSIONSthi(kllesS tO - . -(Jrifice I in. (m In, cttl/daIIloler, /t d i1 0.51 0.1277 0.32442 1.02 .0635 .16133 1.05 .0630 .16004 I 1.60 .0601 ,1526i _ I 2.00 .0630 ,16006 2.83 .0660 .16767 4.00 .0618 .15q08 I 1.06 .0615 ,15629 L 1,01 .0665 .1689al0 I 1,49 ,0639 .1623i all I ,52 .1260 .320012 I 1.00
43、.0590 .1499aAvera_e (Jim ellsions.bElectrical discharge machined.0.065 0.165.065 .165,066 .168,096 .244.126 .320.183 ,475.247 ,627,065 ,165 !.067 .170,095 .241,065 .165,059 .150 II)es( ripti()nSteelSteelSplit brassSplit brassSplit brass, XD : 2 or 14SteelBrassBrass, rectangular ductBrass, a : 45 Ste
44、el, orifice I_DM bSteel, orifire EDM bBrass, two orifices intandemTest Set-Up and InstrumentationThe basic measurements are shown in figure 1.(1) Flow rate at the entrance to the main duct(2) Flow rate through the orifice(3) Main duct static pressure at a point opposite the orifice(4) Static pressur
45、e at the exit plane of the orifice(5) Total temperature of the supply airThe main duct static pressure was measured at a point opposite the orifice in mostcases. This location was selected because it provided a pressure close to the orificeinlet. Model 1, Model 2, and Model 12 were instrumented with
46、 additional pressure tapslocated up to 1.75 inches (4.45 cm) upstream of the orifice. These additional taps wereadded to determine any variations in main duct static pressure with flow through the ori-fice. The position of the static pressure tap at the exit plane was located in the wall of thecolle
47、cting duct as shown in figure 2 This jet static tap location was selected as closeto the exit plane of the orifice as feasible and perpendicular to the axis of the orifice.The total temperature of the supply air was measured by a thermocouple at the rotameterexit when ambient temperature air was use
48、d. The heated air total temperature of theProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-supply air was measuredby a shielded thermocoupleapproximately 10inches (25.4 cm)upstream of the orifice location. The length of pipe betweenthe heater exit and the ori-fice wasfully insulated to prevent heat losses.A measurement of the main duct total pressure was not attempted because of the sizelimitations in the main duct. The total pressure
