超音速邊界層擾動(dòng)演化的數(shù)值模擬研究.pdf

1、天津大學(xué)碩士學(xué)位論文超音速邊界層擾動(dòng)演化的數(shù)值模擬研究姓名：黃章峰申請(qǐng)學(xué)位級(jí)別：碩士專(zhuān)業(yè)：流體力學(xué)指導(dǎo)教師：周恒20030101ABSTRACTRecentlytheproblemoftransitionandstabilityinsupersonicboundarylayerhasattractedmoreandmoreattentionduetoitstechnicalimportanceSofartherearenotmuchre

2、sultsfromthestudyofthestabilityproblemsofcompressibleflowsEspeciallyforsupersonicflows，theoreticalinvestigationsaremostlylimitedtoIinearproblemsRecentlysomepeoplehavetriedtoextendthenonlineartheoryofincompressibleflowsto

3、compressibleflowsHoweverwhetheroneCallmakesuchextensionsdependsonwhethershockletwouldbeinducedbydisturbaIlcesintheflowInthisPapeLtheevolutionof2DdisturbancesinasupersonicboundarylayerofaflatplatewasinvestigatedbyusingDNS

4、Att11eentrance，smallamplitudeTSwavewasintroduced，subsequentlyitsamplitudeincreasedgraduallyandreachedthenonlinearstageofevolutionGiveaDpearsomenon1inearcharacteristicsofitsevolutionweregivenTheproblemofwhethershockletswo

5、uldappearhasbeeninvestigated，thusofferedcertainbasisfortheestablishmentofnon—lineartheoryofstabilityforcompressibleflOWSThedirectnumericalsimulationyieldedthefollowingconclusions：1ThesecondmodeTSwaveismereunstablethanint

6、hefirstmode，anditslargestamplificationrateis45timesofthoseforthefirstmodeTSwave，whichisinconformitywithresultofAreal2Atthelaterstageofevolutionofasmallamplitudedisturbance，whenitsamplitudebecomeslargerdifferentorderharmo

7、nicswillbeexcitedThesecondharmonicexcitedbythefirstmodemightincludethesecondmodeTheamplificationrateofthethirdharmonicisveryclosetotheamplificationrateofthefourthharraonicforbothmodes3Itwouldbetmreli曲letodeterminewhether

8、therewouldbeshockletsbysimplyjudgingiftherewouldbedenselypopulatediSO—Machcontouriso—entropycontourorregionsoflargedivergenceofflowfieldTheeffectivewayistoseeiftheentropyofafluidparticlepassingthroughthe‘‘shocklet’’would

9、haveasuddenincreaseandtoseewhethertherelativevelocityofthefluidparticleiSsupersonicinf而ntofthe“shocklet”andbecomessubsonicaftercrossingtheshocklet4Itwasconfirmedthatshockletswillappearinthefieldwhenthesmallamplitudedistu