The response of asymmetric and planar shock interactions to a continuous excitation of the lower incident shock is investigated numerically. Incident shock waves and centred expansion fans are generated by two wedges asymmetrically deflecting the inviscid free stream flow at Mach 3. The excitations mechanisms considered are (i)Â pitching of the lower wedge traversing the steady-state dual-solution domain (DSD) of regular interaction (RI) and Mach interaction (MI), (ii) a periodic (sinusoidal) oscillation of the lower wedge deflection with a mean value both within and outside of the steady-state DSD and (iii) a periodic (sinusoidal) streamwise oscillation of the lower wedge location with fixed wedge deflection. A detailed analysis of characteristic unsteady flow features, including the Mach stem growth, pressure evolution across the shock system and corresponding flow deflections and entropy rise, is presented with a focus on the bi-directional RIMI transition process. For fast pitching conditions, the MI pattern is maintained far inside the steady-state RI domain. The observed transition limit as the rotational velocity decreases does not fully match steady-state theory, however. This is attributed to geometry-related effects. In the opposite case, transition, good agreement with steady-state theoretical predictions is obtained for slow rotations, and a shock polar analysis applied in the (moving) frame of reference of the shock interaction location improves the agreement with fast pitching numerical data significantly. Furthermore, the MI pattern is found to be more robust against periodic perturbations than the corresponding RI configuration for mean flow conditions inside the steady-state DSD, which appears to be a consequence of the dynamics of the Mach stem during a period of excitation. This is not the case for mean flow conditions outside the steady-state DSD in the RI domain for which a periodic alternation occurs instead.

中文翻译：

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非定常非对称冲击相互作用动力学

数值研究了非对称和平面冲击相互作用对较低入射冲击的连续激发的响应。入射冲击波和中心膨胀风扇由两个楔形不对称地偏转无粘性自由流以 3 马赫产生。 考虑的激励机制是 (i) 下楔形的俯仰穿过稳态双解域 (DSD)规则相互作用 (RI) 和马赫相互作用 (MI)，(ii) 下楔形偏转的周期性（正弦）振荡，在稳态 DSD 内外均具有平均值，以及 (iii) 周期性（正弦）流向具有固定楔形偏转的下楔形位置的振荡。特征非定常流动特征的详细分析，包括马赫杆生长，整个激波系统的压力演变以及相应的流动偏转和熵上升，重点介绍了双向 RIMI 转换过程。对于快速俯仰条件，MI 模式保持在稳态 RI 域内很远的地方。然而，随着旋转速度的降低，观察到的过渡极限并不完全符合稳态理论。这归因于几何相关的影响。在相反的情况下，过渡，对于慢速旋转获得了与稳态理论预测的良好一致性，并且在激波相互作用位置的（移动）参考系中应用激波极坐标分析显着提高了与快速俯仰数值数据的一致性。此外，对于稳态 DSD 内的平均流动条件，发现 MI 模式比相应的 RI 配置更能抵抗周期性扰动，这似乎是激发期间马赫杆动力学的结果。对于 RI 域中稳态 DSD 之外的平均流量条件，情况并非如此，而是发生周期性交替。