凹腔长深比对超声速燃烧室内振荡现象的影响

为研究不同长深比的凹腔对超声速燃烧室内的流动状况及自激振荡现象的影响，采用数值模拟方法改 变凹腔长深比由2至6研究入口来流马赫数为1.58的超声速燃烧室内的压力振荡现象，计算捕捉到了超声速燃 烧室中的压力脉动和凹腔剪切层拟序结构的演化过程以及振荡频率和声压级的变化.研究发现：凹腔内剪切层 状态决定凹腔前后缘激波的强弱；随着长深比增加，振荡增强、声压级变大，而振荡频率整体向低频转变； 长深比不同时振荡主频也在变化.剪切层波动与声波传播相互耦合是导致自激振荡现象的主要原因.
Inordertostudytheinfluenceofdifferentratiooflengthtodepthofcavityontheflowfieldandself-oscilla? tioninsupersoniccombustionchamber,numericalsimulationmethodisusedbychangingtheratiooflengthtodepth from2to6toobservethephenomenonofpressureoscillationinsupersoniccombustionchamberwhentheinletstream Machnumberis1.58.Thescramjetcombustorpressurepulsation,thecavityshearlayercoherentstructureevolutionpro? cessandthechangeofoscillationfrequencyandsoundpressurelevelwerecaptured.Itwasfoundthatthestrengthofthe leadingandtrailingedgeshockwavedependsonthestateofcavityshearlayer.Withlengthtodepthratioincreased,the strengthofoscillationandthesoundpressurelevelincreased,theoveralloscillationfrequencyshiftedtolowerfrequen? cy.Theratiooflengthtodepthaffectsthepeakfrequencytoo.Thecouplingbetweenshearlayerandacousticwaveisthe majorcauseofself-excitedoscillationinsupersoniccombustionchamber.