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Investigation on shear layer instabilities and generation of vortices during shock wave and boundary layer interaction
Computers & Fluids ( IF 2.8 ) Pub Date : 2021-04-16 , DOI: 10.1016/j.compfluid.2021.104966
Abhishek Kundu , Murugan Thangadurai , Gautam Biswas

The interaction of a reflected shock with the boundary layer inside the shock tubes is an important engineering problem. Studies related to shock wave mitigation and attenuation are performed inside the shock tubes. A proper understanding of the flow behind the reflected shock and the separated zone involving multiple vortical structures is highly essential for estimating the effectiveness of the shock wave mitigation/ attenuation. Such complex flows consist of Lambda shock, shear layer originating from the triple point, multiple shocklets, Mach stems, and vortices. Experimentally the shock structures are obtained through optical techniques. The vortices present in the compressible flow can be obtained through numerical simulations. The complex flows consisting of the above- mentioned features have been simulated numerically so far for the Reynolds numbers up to 1000 [ Zhou G, Xu K, Liu F. Grid-converged solution and analysis of the unsteady viscous flow in a two-dimensional shock tube. Phys Fluids 2018;30(016102):1-21.]. In the present investigation, the shock-wave boundary-layer interaction is simulated for the Reynolds numbers of 1000 and 2500 using a 13th order hybrid scheme to discern the distinct flow features. First, the solver [Kundu A, De S. Navier-Stokes simulation of shock-heavy bubble interaction: Comparison of upwind and WENO schemes. Comput Fluids 2017;157:131-145.] was validated with the benchmark wall density data for a Reynolds number of 1000. Next, the simulations were performed using 50 and 109.5 million cells for the Reynolds number of 2500. The density gradients, vorticity, wall density, and Fourier spectra were used for comparing the flow field for the Reynolds numbers of interest. The Lambda shock, Kelvin-Helmholtz (K-H) vortices in the shear layer, shocklets, the height of lambda shock, and Mach stems were obtained using a grid-mesh of 109.5 million cells. It is observed that the number of vortices generated inside the separated flow region increased with the increase in Reynolds number from 1000 to 2500. Furthermore, the triple point height and the number of K-H vortices generated at the shear layer also increase with an increase in Reynolds number. The present simulations revealed the formation of vortices close to the wall at a Reynolds number of 2500. Such flow structures have an important role in shock / blast wave mitigation and the associated aeroacoustics.



中文翻译:

冲击波与边界层相互作用过程中剪切层的不稳定性和涡旋的产生

反射冲击与激波管内边界层的相互作用是一个重要的工程问题。在减震管内部进行了与减震和减震相关的研究。正确理解反射冲击波和涉及多个涡旋结构的分隔带背后的流动,对于评估冲击波缓解/衰减的有效性非常重要。这种复杂的流动包括Lambda激波,源自三点的剪切层,多个小波,Mach杆和涡旋。实验上,冲击结构是通过光学技术获得的。可压缩流中存在的涡流可以通过数值模拟获得。到目前为止,已经对包含上述特征的复杂流进行了数值模拟,其雷诺数高达1000 [Zhou G,Xu K,Liu F.网格收敛解和二维激波中非定常粘性流的分析管子。Phys Fluids 2018; 30(016102):1-21。]。在本研究中,使用13阶混合方案模拟了雷诺数为1000和2500的激波边界层相互作用,以识别不同的流动特征。首先,求解器[Kundu A,De S. Navier-Stokes模拟冲击-重质气泡相互作用:迎风和WENO方案的比较。使用基准壁密度数据对雷诺数为1000的情况进行了Comput Fluids 2017; 157:131-145。的验证。接下来,对于2500雷诺数,使用了50和1.095亿个像元进行了模拟。密度梯度,涡度,壁密度和傅立叶光谱用​​于比较感兴趣的雷诺数的流场。Lambda激波,剪切层中的Kelvin-Helmholtz(KH)涡旋,小波,Lambda激波高度和Mach茎是使用1.095亿个细胞的网格获得的。可以看出,随着雷诺数从1000增加到2500,分离流动区内产生的涡旋数也增加。此外,随着雷诺数的增加,剪切层处产生的三点高度和KH涡旋数也增加。数字。目前的模拟显示,雷诺数为2500时,靠近壁的地方形成了涡流。这种流动结构在减轻冲击波/冲击波和相关的航空声学方面具有重要作用。涡度,壁密度和傅立叶光谱用​​于比较流场中感兴趣的雷诺数。Lambda激波,剪切层中的Kelvin-Helmholtz(KH)涡旋,小波,Lambda激波高度和Mach茎是使用1.095亿个细胞的网格获得的。可以看出,随着雷诺数从1000增加到2500,分离流动区内产生的涡旋数也增加。此外,随着雷诺数的增加,剪切层处产生的三点高度和KH涡旋数也增加。数字。目前的模拟显示,雷诺数为2500时,靠近壁的地方形成了涡流。这种流动结构在减轻冲击波/冲击波和相关的航空声学方面具有重要作用。涡度,壁密度和傅立叶光谱用​​于比较流场中感兴趣的雷诺数。Lambda激波,剪切层中的Kelvin-Helmholtz(KH)涡旋,小波,Lambda激波高度和Mach茎是使用1.095亿个细胞的网格获得的。可以看出,随着雷诺数从1000增加到2500,分离流动区内产生的涡旋数也增加。此外,随着雷诺数的增加,剪切层处产生的三点高度和KH涡旋数也增加。数字。目前的模拟显示,雷诺数为2500时,靠近壁的地方形成了涡流。这种流动结构在减轻冲击波/冲击波和相关的航空声学方面具有重要作用。傅立叶光谱和傅立叶光谱用​​于比较流场中感兴趣的雷诺数。Lambda激波,剪切层中的Kelvin-Helmholtz(KH)涡旋,小波,Lambda激波高度和Mach茎是使用1.095亿个细胞的网格获得的。可以看出,随着雷诺数从1000增加到2500,分离流动区内产生的涡旋数也增加。此外,随着雷诺数的增加,剪切层处产生的三点高度和KH涡旋数也增加。数字。目前的模拟显示,雷诺数为2500时,靠近壁的地方形成了涡流。这种流动结构在减轻冲击波/冲击波和相关的航空声学方面具有重要作用。傅立叶光谱和傅立叶光谱用​​于比较流场中感兴趣的雷诺数。Lambda激波,剪切层中的Kelvin-Helmholtz(KH)涡旋,小波,Lambda激波高度和Mach茎是使用1.095亿个网格的网格获得的。可以看出,随着雷诺数从1000增加到2500,分离流动区内产生的涡旋数也增加。此外,随着雷诺数的增加,剪切层处产生的三点高度和KH涡旋数也增加。数字。目前的模拟显示,雷诺数为2500时,靠近壁的地方形成了涡流。这种流动结构在减轻冲击波/冲击波和相关的航空声学方面具有重要作用。

更新日期:2021-04-23
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