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采用高阶精度有限差分方法直接数值模拟了来流慢声波作用下的钝锥高超声速绕流瞬态流场,分析了自由流扰动波与流场的相互干扰,并应用Fourier频谱分析了边界层扰动波时域和空域演化.结果显示:弓形激波出现连续的“∽”变形,初始扰动被显著放大,边界层内外扰动模态存在明显差别.从空域(沿流线)演化来看,在球头附近低频扰动为主导模态,出了球头区,总扰动模态中的低频和高频成分比例迅速转变,高频模态成分显著地增大.至流场下游,大部分低频分量衰减,或者不再增长,边界层内仅存在特殊频率的不稳定波快速增长.从时域演化来看,比起其他模态,主导模态的发展对上游激励的依赖更大.无论时域还是空域演化,都存在模态竞争现象.
The high-order precision finite-difference method was used to directly simulate the transient flow field of blunt-tip hypersonic flow under the effect of slow sound waves. The mutual interference between the free-flow disturbed wave and the flow field was analyzed. The Fourier spectrum was used to analyze the boundary layer The results show that the bow shock has a continuous “∽” deformation, the initial disturbance is significantly enlarged, and the disturbance modes inside and outside the boundary layer are obviously different. From the perspective of the evolution of the airspace , The low-frequency disturbance near the ball head is the dominant mode. At the ball-head region, the ratio of low-frequency and high-frequency components in the total disturbance mode changes rapidly and the high-frequency mode components increase significantly. Decay, or no longer increase, there is only a rapid increase of unstable waves with special frequencies in the boundary layer.From the time domain evolution, the development of dominating modes relies more on the upstream stimuli than other modes.Whether the time domain Or airspace evolution, there is a phenomenon of modal competition.