基于扰动方程的超音速轴对称射流马赫波辐射研究

摘要

Theoretical investigations have described the growth and decay of instability waves that give rise to Mach wave radiation.In present work,the intense Mach wave radiation by the linear instability waves of a perfectly expanded,axisymmetric jet with an initial centerline Mach number of Ma=2.1 are computed by solving nonlinear disturbance equations.Using linear stability theory,we demonstrate that it is essential to properly address the source of Mach wave radiation.It is also shown that,in supersonic axisymmetric jet,the radiated Mach waves are most intensive in a fixed direction which is perpendicular to the Mach wave front.The intense and location of Mach waves radiation emitter are changed with St numbers.All of our results are in good agreement with direct computations and theoretical analysis.%超音速不稳定波是导致剪切流失稳和转捩的主要不稳定模态,这种模态以马赫波的形式辐射到远场,从而产生强烈的声场.采用线性稳定性理论和非线性扰动方程(NLDE)分析,计算超音速轴对称射流不稳定波的扰动演化(Ma=2.1),对马赫波辐射进行研究,包括马赫波辐射方向、辐射源位置,以及随斯特劳哈尔数的变化情况.研究结果表明,在超音速轴对称射流中,马赫波沿固定方向辐射向远方,不稳定波相位沿另一方向传播,这两个方向相互正交;马赫波辐射源位置位于不稳定波压力幅值最大处;斯特劳哈尔数St越大,马赫波辐射的能力越强,辐射区域越集中.