A Study On Stability And Acoustic Radiation Of Two-dimension Compressible Mixing-layer By Non-linear PSE

Reseach on mixing-layers is not only necessary to the study of turbulence mechanismresearch,but also needed by engineering applications such as burning efective, noise prob-lem.In this paper we focus on two-dimension compressible mixing-layers,similarity solu-tion is employed to calculate the mean flow,in both subsonic and supersonic cases.Then weuse linear stability theory analysis and non-linear parabolic equation to simulate the dis-turbs evolution.According to the result from non-linear PSE, Kirchhof integration is usedto solve the far-field acoustic disturbs.1.In mixing layers, with the growth of Mach number,the growth rate of most amplifiedtwo-dimensional T-S waves is decreasing. Based on the linear stability theory,In the sub-sonic case,two-dimensional waves is the main reason of non-linear efect,the growth rate in-creasing fast and soon reach the saturate point.while in the supersonic case,two-dimensionalwaves in the supersonic cases growing much slower than in the subsonic circumstance andthe saturate point is much latter.2.The non-linear PSE is employed to characterize the feature of instable waves bothsupersonic and subsonic compressible mixing layes.In the subsonic cases,the diferences ofthe mean-flow is not obvious,which makes a slightly symmetry of the distribution of thepressure and stream-wise disturbs.the rotation and merge of the vortex is very clear.In thesupersonic case,the vortical structure is not that notable cause the distribution of large speedratio.3.The far-field is calculated by the Kirchhof surface integration method.THe pressuredisturb distribution is obtained both in subsonic and supersonic.According to the result,theradiation mechanism of mixing-layers varies.In subsonic mixing-layer,we found that thefar-field structure is vortex-paring,without any obvious feature of acoustic radiation beencaptured. But we found clearly mach-wave radiation feature in the supersonic mixing-layer.