关键词: 感受性, 高斯扰动, 直接数值模拟, 线性稳定性分析, 高超声速边界层

Abstract:

The receptivity process of external disturbances entering the boundary layer is crucial for predicting the transition location. Employing a combination of direct numerical simulation and linear stability analysis methods， this study investigates the influence of wall temperature on the receptivity of freestream Gaussian disturbances exciting disturbances within the flare cone boundary layer at Mach number 6. The findings indicate that Gaussian disturbances after passing through the shockwave excite fast acoustic waves and entropy waves at the head of the cone， with the amplitude of the fast acoustic waves being maximized. Additionally， the amplitude of fast acoustic waves increases with the increase of the wall temperature. Subsequently， the fast acoustic waves initiate the fast modal behavior within the boundary layer， and then excite the Mack second mode through a modal transformation mechanism. Decreasing wall temperature stabilizes the first mode， but renders the Mack second mode more unstably. Finally， Fourier transforms applied to the results of direct numerical simulations reveal a pattern of variation of receptivity coefficients with wall temperature， indicating that receptivity coefficients increase with the rise of wall temperature.

Key words: receptivity, Gaussian disturbance, direct numerical simulation, linear stability analysis, hypersonic boundary layer