高对流Mach数三维混合层转捩特性分析及小激波结构模拟  

Transition coherent structures and shocklets in 3-D spatial developing mixing layers at high convective Mach numbers

作　　者：潘宏禄[1] 马汉东[1] 王强[1] 

机构地区：[1]航天空气动力技术研究院,北京100074

出　　处：《空气动力学学报》2008年第3期275-281,共7页Acta Aerodynamica Sinica

摘　　要：采用空间大涡模拟方法对超/超混合、超/亚混合两类三维可压缩平面混合层转捩及其全湍流流场进行了研究,认为混合层动量厚度饱和点可作为流场转捩完成的标志。计算所得到的线性扰动波激励下流场转捩拟序结构与随机扰动下自然失稳结构以及文献结果进行了比对,其结果是一致的,表明了引入线性扰动激励来研究流场转捩结构是合理的。同时,本文还在较高对流Mach数流动下得到了三维流场动态小激波结构,其分布具有非对称特性,且形状与实验及直接数值模拟结果相似。不同条件混合层转捩计算表明:高对流Mach数下混合层转捩以Λ涡结构的形成和发展为主导机制,受扰动及对流条件的影响Λ涡结构不尽相同,某些情况下流场出现二维与三维涡结构共存现象。充分发展湍流区域,流场脉动速度分量量级相同,湍流压缩效应随着对流Mach数提高而明显增强。In this text,two kinds of 3-D spatial developing compressible mixing layers which are supersonic/supersonic and supersonic/subsonic mixing layers are studied. The transition process and full turbulence flows in different convective Mach number are investigated by spatial large eddy simulation （LES）. Hybrid method of a fifth-order upwind compact difference and sixth-order symmetric compact difference schemes are applied for the three-dimensional compressible Favre-filtered Navier-Stokes equations.The computational results show that the most instable disturbance mechanism is 3-D oblique wave perturbation in high convective Mach number. A eddy dominates the transition process and its developing induces the hairpin vortex formation. The coherent structures induced by a pair of oblique first - mode perturbation are consistent to results in random condition and the relevant literature. The vorticity thickness of mixing layer in upstream is increasing linearly and the first maximum position of mixing layer momentum thickness can be seen at the end region of the transition. The instant and statistical parameters are discussed in detail,and the numerical results show a good agreement with the relevant literatures and theory. On the other hand, shocklets have been captured by LES method in convective Mach number 1.0. Their distribution is unsymmetrical and their characteristics have been analyzed in text. In full turbulent region, the compressible effect increases with convective Math number elevating.

关 键 词：可压缩混合层 转捩 湍流 大涡模拟 直接数值模拟 

分 类 号：O357.5[理学—流体力学] V211.3[理学—力学]