1、hNASA-TP-1652 19800015109 !NASA Technical Paper 1652 iMeasured and Predicted ShockShapes and AerodynamicCoefficients for Blunted Conesat Incidence in Air at Mach 5.9Robert L. Calloway and Nancy H. WhiteMAY 1980-“ 1 ! iI._A_Q1rY ,_r_: _“H CENTERLIBRARY, iqASAHAMPTON VIRGIrqlA1/L5/%Provided by IHSNot
2、for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA Technical Paper 1652Measured and Predicted ShockShapes and AerodynamicCoefficients for Blunted Conesat Incidence in Ai
3、r at Mach 5.9Robert L. Calloway and Nancy H. WhiteLangley Research CenterHantpton, VirginiaNational Aeronauticsand Space AdministrationScientific and TechnicalInformationOffice1980Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for
4、 ResaleNo reproduction or networking permitted without license from IHS-,-,-SUMMARYExperimentalvaluesof shockshapes (anglesof attack e of 0O and 10)and staticaerodynamiccoefficients(_= -4 to 12) for sharpand sphericallybluntedconeshaving cone half-anglesof 30, 45, 60, and 70 and nose-bluntnessratios
5、of 0, 0.25,and 0.50 are presented. Shockshapeswere alsomeasuredat e = 0 by using a flat-facedcylinder(90 cone)and a hemispher-icallybluntedcylinder (sphere). All testswere conductedin air (ratioofspecificheats y of 7/5) at a free-streamMach numberof 5.9 and a unit free-streamReynoldsnumberof 2.80 10
6、6per meter. Comparisonsbetweenmeasuredvalues andpredictedvalueswere made by usingseveralnumericaland simpleengineeringmethods.Presentresultsare generallyin excellentagreementwithmeasuredresultsfrom othersourcesand with the predictedvalues from severalnumericalmethods.A modifiedNewtonianmethodprovide
7、dconsistentlypoor agreementwithmeasuredaxial-forcecoefficientsandwith normal-forceandpitching-momentcoefficientsfor the 60 cone. Measuredstaticaerodynamiccoefficientsfor the largehalf-angleconesshow that theeffectsof nose-bluntnessratiosare small, indicat-ing thelack of importanceof thisparameterin
8、the aerodynamicdesignof entryprobeshavinglargehalf-anglecone forebodies.INTRODUCTIONThe sphericallybluntedcone has been usedas the forebodyshapeof theplanetaryentryprobefor both theViking ProjectandPioneerVenus, and itwill be used againfor theupcomingProjectGalileo (JupiterProbe). The finalaero-ther
9、modynamicdesignfor theseplanetaryentryprobesmust be determinedby analyticaltechniquesbecausethe entryenvironmentof otherplanetscannotbe simulatedby usingEarth-basedexperimentalfacilities. Experimentalresultsare needed,though,to validatethe theoreticalmethodsand to provideinputsfor empiricaltechnique
10、sor correlationprocedures(ref.1). Throughproperuseof bothmeasuredand predictedresults,futureplanetaryprobes can bedesignedwith less conservatismso thatmore payloadcanbe accommodated.Resultsfrom experimentalstudiesconductedon sharpand sphericallybluntedconesin air at supersonicandhypersonicMach numbe
11、rsare extensive.Most of the earlywork (aerodynamiccoefficientsand pressuremeasurements)was conductedon coneswith smallhalf-angles(8_ 40) becausetheywerecandidatesfor ballisticreentryintoour own atmosphere. References2 and 3provide,respectively,summarytablesand a compilationof themajor body ofdata on
12、 conesup throughthemid-960s. Particularexamplesof someof theearlyexperimentalwork are given in references4 to 11. In laterwork(refs.12 to 19), coneswith largerhalf-angleswere studiedwith increasinginterestas candidateconfigurationsfor planetaryentryprobesand for basicresearchin areasforwhich datawer
13、e lacking.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The purposeof this reportis to presenta portionof the resultsfrom astudywhich is designedto enrich the hypersonicdata base forentry-typegeom-etriesover a rangeof anglesof attack,ratiosof speci
14、ficheats,andMachnumbers. The presentresults (andthoseof ref. 20) are part of a systematicstudyof aerodynamiccoefficientsand shockshapesat anglesof attackwhichare valuablefor validationof predictionmethodsand completionof thehyper-sonicdata base. Experimentalresultspresentedhereinare for sharpandsphe
15、ricallybluntedconeshaving cone half-anglesof 30, 45, 60, and 70and nose-bluntnessratiosof 0, 0.25,and 0.50. These configurationsweretestedin theLangley20-InchMach 6 Tunnel at a Mach numberof 5.9. Measure-ments includeshockshapesat _ = 0 and 0 and staticaerodynamiccoeffi-cients takenat 2 incrementsfo
16、r e = -4 to 2. Shock shapesat 0 angleof attackfor a 90 cone and fora spherewere obtainedby usinga flat-facedcylindermodel and a hemisphericallybluntedcylindermodel, respectively.Comparisonsbetweenmeasuredvaluesand predictedvaluesaremade by usingseveralnumericalmethods and simpleengineeringmethods. A
17、lso, experimentaldata from references21 to 26 are comparedwith thepresentresults.SYMBOLSAxial forceCA axial-forcecoefficient,PitchingmomentCm pitching-momentcoefficient, qSdNormal forceCN normal-forcecoefficient,Cp,max Newtonianpressurecoefficientd model base diameter,cmZ model length,cmMz localMach
18、 numberM_ free-streamMach numberPt stagnationpressure,kPaq_ free-streamdynamicpressure,kPaRoo,d free-streamReynoldsnumberbasedon drb model base radius,cmrn modelnose radius,cm2Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-rn/rb nose-bluntnessratioS
19、 model base area,cm2Tt stagnationtemperature,KV_ free-streamvelocity,m/secx,r cylindricalcoordinates(fig.1(a)angleof attack,degy ratioof specificheats_* boundary-layerdisplacementthickness,cmdistancebetweenmodel surfaceand shockwave, measuredparalleltomodel axis,cm (fig.(a) cone half-angle,degdet mi
20、nimumcone half-anglefor shockdetachment,degFACILITYANDTESTOONDITIONSShockshapesand staticaerodynamiccoefficientswere obtainedfrom flowvisualizationand forceandmoment testsconductedin the Langley20-InchMach 6 Tunnel. Operation,flowconditions,and detailsof force testinginthisfacilityaredescribed in re
21、ference27. All testswere conductedat thefollowingflowconditions:M_= 5.9Pt = 276kPaTt = 431 KR_,d = 0.42 06 (cones)R_,d = 0.07x 06 (cylinders)MODELSFigure1(a) providesa generalplanformview and thedimensionsof the2 cone models tested. Thesemodelswere constructedfrom aluminumand have3Provided by IHSNot
22、 for ResaleNo reproduction or networking permitted without license from IHS-,-,-base diametersof approximately5.08 cm. Cone half-anglesof 30, 45, 60,and 70 were examined,and the nose-bluntnessratios (0,0.25,and 0.50)werevariedfor each cone half-angle. A flat-facedcylinderanda hemisphericallybluntedc
23、ylinder,each with base diametersof 3.81cm (fig.(b),were testedat _ = 0 to provideshockshapesfor a 90 cone and a sphere,respectively.A photographof the cone models testedis shown in figure2. The taperedcylindricalsectionextendingbehindthemodel forebodywasdesigned to housethe strain-gagebalance. These
24、modelswere also used for theexperimentaltestsin heliumdescribedin reference20.TEST METHODSFlow visualizationand forceand moment testswere conductedsimulta-neously. Schlierenphotographswere used to obtain themeasuredshockloca-tionsat _ = 0 andat _ = 10. The shocklocationswere read manuallyfromphotogr
25、aphssimilarto the one shownin figure3. The error in thesemeasure-ments is estimatedto be .5percentof rb,which is aboutthe indicatedthicknessof theshock wave in the photograph. Shock-layerthicknessesweremeasuredparallelto themodel axis (seefig. (a)and are presentedin tableI. For valuesof r/rb greater
26、than .0, A wasmeasuredfrom animaginaryextensionof theplanedefinedby thebase of themodel.Aerodynamicforceand moment testswereperformedwith themodels mountedon a sting-supported,five-componentstrain-gagebalance (norolling-momentcomponent). The straightstingwas attachedto the angle-of-attackmechanisman
27、d datawere obtainedin 2 incrementsof angleof attackfrom -4 to 2.The angleof attackwas setopticallyby usinga point lightsourceadjacenttothe test sectionand a smalllens-prismmountedon the taperedcylindricalsec-tion extendingbehind themodel. The imageof the sourcewas reflectedby theprismand focusedby t
28、he lens onto a boardwhichwas calibratedto indicatetheangleof attack. Data were obtainedduringthe test runs with themodel setatdiscreteangles of attack. The accuracyof determiningthe angleof attack inthismanner is estimatedto be 0.25. All testswere conductedat a sideslipangleof 0, and no base pressur
29、eswere measured.The referencearea for themodelswas thebase area S and the referencelengthwas thebase diameter d. All pitching-momentdata were reducedaboutthe actualnose of each model. The estimateduncertaintiesin themeasuredstaticaerodynamiccoefficientsbasedon a balanceaccuracyof 0.5percentofthe des
30、ignloadsare as follows:dCN . 0.020dCA . 0.00Acm . o.oloThe measuredstaticaerodynamiccoefficientsare presentedin tableII.4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-PREDICTIONMETHODSIn termsof theMach numberbetweenthe shockwave and the body MZ, s
31、ev-eral flow conditionswill occurfor the rangeof cone half-anglesand nose-bluntnessratiostested. For u = 0, the flow conditionsthat can occurareillustratedin figure4. For the sharpconewith det,therewill be subsonicflow over the entirebodywith the sonicline (locusof pointswhere Mz = 1.0) extendingfro
32、m the shockwave to the base of the body,as shownin figure4(b). For the sharpconethere is a limitedrangeof cone half-angleswhichcausesa regionof sub-sonicflow adjacentto the surface (notillustrated).The size of thisregionincreasesas approaches edet,but the shockwave remainsattached.For air at M_= 6.0
33、 this occursbetween = 53 and 0 = det = 55.4(ref.28).When the cone is sphericallybluntedand 0det (fig.4(d),subsonicflow occursover theentirebody (regardlessof the nose bluntness),and the flow conditionsaresimilarto thoseof figure4(b). Themost complicatedflow conditionsoccurwhen thereis subsonicflow o
34、ver the nose but is not smallenoughto allowthe flow to becomecompletelysupersonicaft of the sphere-conejunctionandnot largeenoughto producetotalsubsonicflow in theshocklayer (fig.4(e).The sonicline can assumeseveralshapesfor valuesof 0 in this range,includingtheone shownin figure4(e). For anglesof a
35、ttackother than 0,combinationsof the flowconditionsshown in figure4 can occursimultaneouslyin differentmeridionalplanes,dependingon the combinationof cone half-angle,nose bluntness,and angleof attack.A numberof numericalmethodswere used to predictshockshapesand pres-sure coefficientsfor the configur
36、ationsstudied. Thesemethodswere used pri-marily becauseof theiraccessibilityand becausethey coveredthe rangeofflow conditionsbeingstudied. In additionto integratingthe pressurecoeffi-cientsto determinepredictedstaticaerodynamiccoefficients,valuespredictedby Newtonianmethodsfrom reference29 were also
37、 used for comparison. The fol-lowingtableliststhe numericalmethodsused and indicatesthe localflow con-ditions (aspreviouslydescribed)to which theywere applied:All All Subsonicnose,lSubsonicnose,Author Referencecapabilitysupersonicsubsonic supersonic mixedon coneconeKlunker,South,and Davis 30 X XKuma
38、r and Gravesa 31 X X Xzoby andGraves 32 XMorettiand Bleich 33 X XSutton 34 X X XBarnwell 35 X XSouth 36 XaSolutionincludesthe effectsof viscosity.See reference20 for a briefdescriptionof thesetheoreticalmethods.5Provided by IHSNot for ResaleNo reproduction or networking permitted without license fro
39、m IHS-,-,-RESULTSAND DISCUSSIONSShockShapes for 0 Angleof AttackSharpcones.-Measuredand predictedshockshapesfor sharpconeswith8 = 30 and 45 (figs.5(a) and (b)show the straightshockwave that isobtainedwhen it is attachedto thebody and the localMach number is super-sonic. Althoughthe inviscidmethodsof
40、 references28 and 30 provideexcellentagreement(within2 percent)with measuredshock-layerthicknessesfor bothcone half-angles,calculatingtheboundary-layerdisplacementthickness 6“and adding it to theoriginalbody to get an equivalentshaperesultsin fur-ther improvementin the agreementbetweenmeasuredand pr
41、edictedvalues. Anundocumentedlaminar,similarboundary-layersolutionwrittenby RalphD.Watson of theLangleyResearchCenterwas used to calculatethedisplacementthicknessesfor thesetwo cases.For the sharpconeswith = 60 and 70 (figs.5(c)and (d),the shockwave is detachedand the localMach number is subsonic. T
42、he methodof refer-ence 36 was used to predictthe shockshapesby inputtinga nose-bluntnessratio rn/rb of 0.0,resultingin excellentagreementbetweenmeasuredandpredictedvaluesforboth cone half-angles.Shock shapesfor a 90 conewere measuredfrom schlierenphotographsof aflat-facedcylinderand are comparedwith
43、 predictedvalues (refs.35 and 36) infigure6. Good agreement(within5 percent)betweenmeasuredandpredictedshock-layerthicknessesis shownby both methods.Blunt cones.-Measuredandpredictedshock shapesfor the sphericallybluntedconesat _ = 0 arepresentedin figure7. For = 30 andrn/rb = 0.25and 0.50 (figs.7(a
44、) and (b),the localflow is subsonicin thenose regionand supersonicover the conicalafterbodyas indicatedby the pre-dicted (ref.34) sonicline. There is excellentagreementbetweenmeasuredandpredicted (refs.31 to 34) shocklocations,except that the approximatemethodof reference32 slightlyunderpredictsthes
45、hock shapeaft of the sphere-conejunctionfor rn/rb = 0.50.Measuredshockshapesfor 8 = 45 and both nose-bluntnessratios(figs.7(c) and (d)are in excellentagreementwith predictedshockshapesfrom references31, 32, and 34. By assumingcompletelysupersonicflow alongthe conicalafterbody,it was possibleto use t
46、he approximatemethodof refer-ence 32. Themethodof reference33 was not applicablebecauseof the presenceof subsonicflowalong theconicalafterbodyas indicatedby the soniclinespredictedby themethod of reference34.As shownby the soniclines (calculatedby themethod of ref. 35), theentirelocalflow field is s
47、ubsonicfor = 60 and 70 and rn/rb = 0.25and 0.50 (figs.7(e), (f), (g),and (h). All threemethods (refs.34 to 36)used to calculatethe shock shapesfor thesefour casesprovideexcellentagreementwithmeasuredvalues.Shockshapesfor a spherewere measuredfrom schlierenphotographsof thehemisphericallybluntedcylin
48、der(rn/rb = .00)and comparedwith predicted6Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-values (refs. 32 to 34) in figure 8. The excellent agreement between measuredand predicted shock shapes for the sphere was expected since all the previouscomparisons had shown excellent agreement in the spherically blunted noseregion for cones with 1Sonic lineNI_I I M_IoniC line iivI_t I -ivl_t_i - (e)Bluntedcone; det“ 0Figure4. Exampleso l
