Zhang Lite, Feng Zilong, Sun Mengyu, Jin Haozhe, Shi Honghui
School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Entropy (Basel). 2021 Aug 16;23(8):1051. doi: 10.3390/e23081051.
This study is focused on the propagation behavior and attenuation characteristics of a planar incident shock wave when propagating through an array of perforated plates. Based on a density-based coupled explicit algorithm, combined with a third-order MUSCL scheme and the Roe averaged flux difference splitting method, the Navier-Stokes equations and the realizable -ε turbulence model equations describing the air flow are numerically solved. The evolution of the dynamic wave and ring vortex systems is effectively captured and analyzed. The influence of incident shock Mach number, perforated-plate porosity, and plate number on the propagation and attenuation of the shock wave was studied by using pressure- and entropy-based attenuation rates. The results indicate that the reflection, diffraction, transmission, and interference behaviors of the leading shock wave and the superimposed effects due to the trailing secondary shock wave are the main reasons that cause the intensity of the leading shock wave to experience a complex process consisting of attenuation, local enhancement, attenuation, enhancement, and attenuation. The reflected shock interactions with transmitted shock induced ring vortices and jets lead to the deformation and local intensification of the shock wave. The formation of nearly steady jets following the array of perforated plates is attributed to the generation of an oscillation chamber for the inside dynamic wave system between two perforated plates. The vorticity diffusion, merging and splitting of vortex cores dissipate the wave energy. Furthermore, the leading transmitted shock wave attenuates more significantly whereas the reflected shock wave from the first plate of the array attenuates less significantly as the shock Mach number increases. The increase in the porosity weakens the suppression effects on the leading shock wave while increases the attenuation rate of the reflected shock wave. The first perforated plate in the array plays a major role in the attenuation of the shock wave.
本研究聚焦于平面入射激波在穿过多孔板阵列时的传播行为和衰减特性。基于基于密度的耦合显式算法，结合三阶MUSCL格式和Roe平均通量差分分裂方法，对描述气流的Navier-Stokes方程和可实现的-ε湍流模型方程进行了数值求解。有效地捕捉并分析了动态波和环形涡旋系统的演化。利用基于压力和熵的衰减率，研究了入射激波马赫数、多孔板孔隙率和板数对激波传播和衰减的影响。结果表明，前导激波的反射、衍射、透射和干涉行为以及尾随二次激波的叠加效应是导致前导激波强度经历由衰减、局部增强、衰减、增强和衰减组成的复杂过程的主要原因。反射激波与透射激波诱导的环形涡旋和射流相互作用导致激波变形和局部强化。多孔板阵列后形成近乎稳定的射流归因于两块多孔板之间内部动态波系统振荡腔的产生。涡核的涡度扩散、合并和分裂耗散了波能量。此外，随着激波马赫数增加，前导透射激波衰减更显著，而阵列第一块板的反射激波衰减不太显著。孔隙率的增加削弱了对前导激波的抑制作用，同时增加了反射激波的衰减率。阵列中的第一块多孔板在激波衰减中起主要作用。
