Ma数对后掠机翼流动非线性失稳的影响

The Mach number effect on the nonlinear instability of swept-wing flows

横流非线性失稳是导致后掠机翼流动湍流转捩的主要因素,而目前大部分的研究都集中在不可压缩流动.首先,本文采用非线性抛物化扰动理论分析了来流Ma=0.1,0.7,1.5,2.0条件下,后掠机翼流动的非线性失稳过程.计算结果表明来流Ma数激励了横流涡的发展,增加了饱和横流涡的流向涡量,并且来流Ma数增加,使得饱和横流涡趋近壁面.其次,通过对饱和横流涡二次失稳的分析,本文计算结果表明来流Ma数增强了饱和横流涡的二次失稳,并且在亚声速来流条件下,二次失稳"z"模态占优,而在超音速来流条件下,二次失稳"y","z"模态同时占优.

The crossflow instability is the main factor triggering the transition over the swept-wing, at present, most works focus on the incompressible flow. In this paper, the crossflow nonlinear instability of the swept wing flow is investigated using the nonlinear parabolized stability equations （NPSE） with the free stream Ma=0,1, 0.7, 1.5 and 2.0, The crossflow vortex turns out to be more unstable and the minimum local streamwise vorticity increases when the free stream Ma number increases, and compared to the incompressible case, the supersonic crossflow vortex structure is situated much closer to the wall. The crossflow secondary instability may be amplified by the free stream Ma number based on secondary instability analysis, the secondary instability ＂z＂ mode will be dominant when the free stream velocity is subsonic, while tile secondary instability ＂y＂ and ＂z＂ mode will be both dominant when the free stream velocity is supersonic.