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数值研究了冷流及反应流情况下超燃冲压发动机二维凹腔剪切层的非定常特性。应用混合RANS/LES方法预报非定常流场,该模型很好地捕捉到了非定常大尺度结构并揭示了凹腔剪切层的演化。着重研究了凹腔上游横向喷流和燃烧放热对凹腔剪切层行为的影响。结果表明:凹腔上游横向喷流使凹腔剪切层增厚并上抬,同时减弱了剪切层与凹腔后壁的撞击,明显抑制了凹腔-剪切层自激振荡;燃烧发生后,凹腔剪切层进一步上抬,凹腔自激振荡大幅减弱,同时压力振荡转到相对较低的频率。
The unsteady behavior of two-dimensional cavity shear layer of a scramjet engine is investigated numerically under cold and reactive flow conditions. The mixed RANS / LES method is used to predict the unsteady flow field. The model can well capture the unsteady large-scale structure and reveal the evolution of the cavity shear layer. The effects of transverse jet flow and combustion heat release on the cavity shear layer behavior are mainly studied. The results show that the horizontal jet flow in the upstream of the cavity thickens and lifts the cavity shear layer and weakens the collision between the shear layer and the cavity rear wall and significantly inhibits the self-oscillation of the cavity-shear layer. The combustion occurs After that, the cavity shear layer is further lifted and the cavity self-excited oscillation is drastically weakened, at the same time the pressure oscillation is shifted to a relatively lower frequency.