Receptivity of Mack modes to localized unsteady blowing and suction in a chemical non-equilibrium hypersonic boundary layer  

化学非平衡的高超声速边界层中由局部非定常吹吸引起的Mack模态感受性

作　　者：Qingjiang Yuan Runjie Song Ming Dong 袁庆江;宋润杰;董明(Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]State Key laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Acta Mechanica Sinica》2024年第7期1-18,共18页力学学报（英文版）

基　　金：supported by the National Science Foundation of China(Grant Nos.U20B2003,11988102,12302292).

摘　　要：This paper studies the local receptivity of the Mack-mode instability to localized unsteady blowing and suction(UBS)in a chem-ical non-equilibrium(CNE)hypersonic boundary layer.The five-species CNE model is employed,and the receptivity efficiency is formulated by use of the residual theorem.Compared with the results for the calorically perfect gas(CPG)model,we find that the real-gas effect enhances the receptivity efficiency remarkably in the majority of the second-mode frequency band,and the enhancement is mainly attributed to the modification of the base flow due to the CNE effect,which is akin to the cold-wall effect in hypersonic boundary layers.Combined with the destabilizing role of the CNE effect on the Mack second mode,it is concluded that the CNE effect would lead to a greater linearly accumulated perturbation amplitude,implying premature of transition to turbulence in a high-enthalpy hypersonic boundary layer subject to localized perturbations.针对考虑化学非平衡效应的高超声速边界层,研究了由局部非定常吹吸引起的Mack模态感受性机制.采用5组分化学非平衡模型,通过留数定理定量刻画了感受性效率.通过与量热完全气体模型计算结果的对比,发现在Mack模态的大部分失稳频段,化学非平衡效应极大地促进了感受性系数.这种促进效果主要源于化学非平衡效应大大降低了基本流的壁面温度,这与壁面冷却的影响类似.化学非平衡效应不仅会放大Mack模态的感受性系数,还促进其增长率,因此两者的共同作用将导致高焓边界层转捩提前.

关 键 词：Chemical non-equilibrium flow Boundary-layer instability HYPERSONIC RECEPTIVITY Transition to turbulence 

分 类 号：O35[理学—流体力学]