REG NACA-TN-3668-1956 Preliminary investigation of a family of diffusers designed for near sonic inlet velocities.pdf

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1、IFORAERONAUTICS I0.50).Themaximumtotalamplitude,andalsothefrequency,gincreasesteadily 1withincreasingmass-flowratio.,Theuniformityofthetotal-pressureprofilesinfigure14indicatesthatthebasicoscillationisprobablynotduetoflowseparationwhichalsoindicatesthattheexitslopewadnottoolarge.Increasingboundary-l

2、ayerthiclmessresultedingreaterunsteadinessand,occasionally,singlehigh-amplitudeoscillationswouldoccura71 Insomemodelsa definitebeatfrequencyofrisingandfalling?l?hepredominantt frequencyincreasedtoamaximumvalueofapprohow-ever,somechangeinflowunsteadinessisshowninfigwe!Z1.Theflowuniformitywaslittleaff

3、ected.-_-AirJeakageintoduct.-Theleakageinvestigatedoccurredthroughgroupsofl/32-inch-diameterholesdrilledatabout3/32-inchspacingsateachductstationasshowninfigure20(c).Leakageintothedown-streampartoftheducthadlittleeffectonpressurerecovery.A sig-nificantreductionh total-pressureratiooccurredathighmass

4、-flowratioswhenleakagewasallowednearthethroataswellasinthedown-streamregion.Slmmwyofsurface-conditiontests.-Itwasanticipatedthatthe13.50-0ductwouldbeparticularlysensitivetosurfaceconditionsbecauseofthelsrgemaDesiguData.BritishR.A.E.TNNo.Aero.1973,SD.84,Sept.1948.11. Naumann:DiffuserEfficienciesatHig

5、hSubsonicVelocities.Rep.No.l?B1705,TechnicalInstituteforAerodynamics,Aachen,Mar.30,1943.12. Seddon,J.: AirIntakesforAircraftGasTurbines.Jour.Roy.Aero.Sot.,Oct.1952,pP.749-787.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACAm 3668 2113. Garner, H.

6、 C.: TheDevelopmentof TurbulentBoundaryLayers.R andM 2133,BritishA.R.C.,June1944.14. Wyatt,DeMarquisD.: AnalysisofErrorsIntroducedbySeveralMethodsofWeightingNonuniformDuct Flows. NACATN34-00,1955.15. Nussdorfer, T. J.: SomeObservationsof Shock-InducedTurbulentSeparation on Supersonic Diffusers. NAcA

7、RME51L26,1954.16. Persh, Jerome, andBaileyj BruceK“ fects of surface ROuessOver the IbwnstreamRegion of a 23 Conical Diffuser. NACATN3066, lg5k. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-22 NACAm 3668Provided by IHSNot for ResaleNo reproductio

8、n or networking permitted without license from IHS-,-,-EProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-A!So.m Nralghtwring vonwMdd tesi -dlffuserJ - - -+ 6.CKI*+!4 Geneml arrangement Note: All dknens40nsIn hchesu YModel detailTo mProvided by IHSNot

9、for ResaleNo reproduction or networking permitted without license from IHS-,-,-2.42.21,21,0Figure 7.-00 Jo .20 .30 .40 .50 .60 .70 .80 .90 1.00Mass- flow ratio , “%,.Flow u.nifordtyparameter as a function of maEs-flow ratio and total-pressure ratio.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-