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压缩拐角激波与边界层干扰问题广泛存在于高速飞行器的外部和内部流动中,其非定常复杂流场结构对飞行器气动性能影响显著。动力学模态分析将有助于进一步加深理解激波与边界层干扰流场不同特征频率对应的流动结构及动力学特性,为揭示其复杂流动机理提供参考。本文采用动态模态分解方法对来流马赫数2.9,24°压缩拐角内激波与超声速边界层干扰下的非定常流动进行了模态分析。评估了稀疏改进动态模态分解方法在压缩拐角流动中的适用性,研究了湍流干扰和转捩干扰下典型特征频率对应的动力学模态空间结构差异及其原因,分析了转捩边界层展向非均匀性对低频/高频模态动力学机制的影响规律。研究发现,湍流干扰与转捩干扰下拐角干扰区内均存在两类截然不同的动力学模态:低频模态和高频模态。低频模态结构集中在分离激波及分离泡剪切层的根部,表征为分离泡的大尺度膨胀和收缩运动;高频模态空间分布则以平均音速线附近正负交替结构为主,对应为边界层内不稳定波沿剪切层往下游的传播。转捩边界层的展向结构对低频模态运动特性影响明显,而对高频模态的影响则相对较小。
Compressional corner shock and boundary layer interference problems exist in the external and internal flow of high-speed aircraft. The unsteady complex flow field structure has a significant impact on the aerodynamic performance of the aircraft. Dynamic modal analysis will help to further understand the flow structure and dynamics characteristics corresponding to different characteristic frequencies of shock and boundary layer disturbing flow fields, and provide reference for revealing the complex flow mechanism. In this paper, the modal analysis of the unsteady flow under the interference of shock wave and supersonic boundary layer at Mach number compression of 2.9 and 24 ° by using the method of dynamic mode decomposition was carried out. The applicability of the sparsely modified dynamic mode decomposition method in compressing the corner flow was evaluated. The differences of the dynamic modal spatial structure corresponding to the typical eigenfrequencies under turbulence and turbulence disturbances and their causes were analyzed. The effects of turbulent boundary layer transition Influence of non-uniformity on low-frequency / high-frequency mode dynamics. It is found that there are two distinct types of dynamic modes in the corner area under turbulence disturbance and transition disturbance: low-frequency mode and high-frequency mode. The low-frequency mode structure concentrates on the separation shock and the root of the separation bubble shear layer and is characterized by large-scale expansion and contraction movements of the separation bubble. The high-frequency mode spatial distribution is dominated by alternating positive and negative structures near the average sound velocity line, corresponding to the boundary layer The propagation of unstable waves along the shear layer downstream. The roll-to-roll boundary layer structure has a significant effect on the low-frequency modal motion, while the effect on the high-frequency modal is relatively small.