基于稳态射流控制的高超声速激波/湍流边界层干扰流动结构与非定常性研究

Flow structures and unsteadiness in hypersonic shock wave/turbulent boundary layer interaction subject to steady jet

对稳态射流作用下马赫6高超声速压缩拐角激波/湍流边界层干扰流动开展了直接数值模拟研究.表面摩阻系数、壁面压力、平均速度和温度、边界层厚度和斯坦顿数的分布等结果表明,激波/湍流边界层相互作用区的流动发生了显著变化.研究发现,垂直壁面的稳定射流对抑制流动分离没有任何作用,反而增加了其空间尺度.瞬时流动结构表明,在施加流动控制后,可以观察到湍流增强效应,并出现大量的类Görtler涡结构,但主激波强度降低.使用加权功率谱密度分析壁面脉动压力信号,我们发现了一件有趣的事情:尽管稳定射流抑制了分离激波引起的低频振荡现象,但射流激波附近的壁面脉动压力以低于0.1u∞/δref的频率振荡.相干性和间歇性因子的结果表明,这与射流激波本身的往复运动有关.

Direct numerical simulations of Mach 6 hypersonic flow over a 34°compression corner subject to steady jet are conducted.Distributions of skin friction coefficient,wall pressure,mean velocity and temperature,boundary layer thickness and Stanton number demonstrate that the flow changes dramatically in the shock wave/turbulent boundary layer interaction area.It is found that the steady jet has no effect on suppressing flow separation unexpectedly,but increases its spatial scale instead.Instantaneous flow structures show that the turbulence amplification can be observed after the application of flow control,and abundant Görtler-like vorticities appear,but the strength of the main shock decreases.Analyzing the wall fluctuating pressure signals using weighted power spectral density,we found an interesting thing.That is,although the low-frequency oscillation phenomenon induced by separation shock is suppressed by the steady jet,wall fluctuating pressure beneath the jet shock is oscillating at a frequency lower than 0.1u∞/δref.Results of coherent and intermittency factor reveal that it is related to the backand-forth movement of the jet shock itself.