论文部分内容阅读
本文通过采用混合型的四阶精度频谱关系保持格式和基于信号特征传播的边界处理方法，对对流马赫数分别为０．５、０．９和１．４的时间发展和超声速空间发展的剪切流动进行了数值模拟．目的是对剪切层不稳定结构的演化方式、相同对流马赫数下时间发展和超声速空间发展的剪切流动的异同作初步研究，研究表明，对时间发展的剪切流动来说：（１）当Ｍｃ＝１．４时，剪切层内流动演化的形态为：首先压力等值线在其极值点处产生中心型结构，且极大值点和极小值点交替分布．然后中心型结构进一步发展并产生横向分裂，从而在剪切层内等压力线出现鞍点结构随后剪切层内重新产生中心型的压力极值点结构，进而又出现鞍点结构、如此发展下去，剪切层内的压力等值线呈现中心和鞍点的组合．剪切层外的压缩波沿特征线方向传播并加强，形成类激波的结构，最后在流场中包含许多压缩和膨胀波在计算时间内流向的周期性未受破坏．（２）当Ｍｃ＝０．５时，初始的流向的周期结构经过一定时间后将丧失其稳定性在计算域为两个扰动周期的情况下，扰动形成的旋涡的后期演化表现为涡的对并．（３）对Ｍｃ＝０．９的流动，演化图象介于前两者之间．对具有相同对流马赫数的空间问题来说，由于粘性和非线性发展对周期性的破坏，随着?
In this paper, we adopt a hybrid fourth-order spectral precision preserving format and a boundary-based processing method based on signal feature propagation. For the convective Mach number, the time-developed and supersonic space-developed shear Flow was numerically simulated. The purpose is to study the evolutionary modes of shear instability structure, the similarities and differences of the shear flow at the same convection Mach number and the shear flow of supersonic space development. The results show that for the shear flow of time development: (1) When Mc = 1.4, the evolution of shear flow in the shear layer is as follows: First, the pressure contour produces a central structure at its extreme point with alternating distribution of maximum and minimum points. Then the central structure further develops and produces lateral splitting so that a saddle-point structure emerges on the isopressure line in the shear layer and then a central pressure extreme point structure is regenerated in the shear layer and a saddle-point structure appears again, thus developing and scissoring The pressure contour within the slice presents a combination of center and saddle point. The compressional wave outside the shear layer propagates and strengthens along the direction of the characteristic line to form the shock-like structure. Finally, the flow field contains many periodic unscathed flows of compressional and expansion waves in the calculation time. (2) When Mc = 0.5, the periodic structure of the initial flow will lose its stability after a certain period of time. In the case of two perturbation cycles in the computational domain, the later evolution of the turbulent vortex is represented by the vortex and. (3) For the flow of Mc = 0.9, the evolutionary image is between the first two. For the space problem with the same convection Mach number, due to the periodic damage caused by the development of viscous and non-linear, with?