Characteristics of the Mach Disk in the Underexpanded Jet in which the Back Pressure Continuously Changes with Time

(整期优先)网络出版时间:2003-02-12
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Whenthehigh-pressuregasisexhaustedtothevacuumchamberfromthenozzle,theunderexpandedsupersonicjetcontainedwiththeMachdiskisgenerallyformed.Theeventualpurposeofthisstudyistoclarifytheunsteadyphenomenonoftheunderexpandedfreejetwhenthebackpressurecontinuouslychangeswithtime.ThecharacteristicoftheMachdiskhasbeenclarifiedinconsiderationofthediameterandpositionofitbythenumericalanalysisinthispaper.ThesonicjetoftheexitMachnumberMe=1isassumedandtheaxisymmetricconservationalequationissolvedbytheTVDmethodinthenumericalcalculation.ThediameterandpositionoftheMachdiskdifferswiththeresultsofasteadyjetandtheinfluenceonthecontinuouslychangingofthebackpressureisevidencedfromthecomparisonwiththecaseofsteadysupersonicjet.