汇聚激波诱导具有正弦扰动双层重气柱界面的演化机理  

Evolution mechanism of double-layer heavy gas column interface with sinusoidal disturbance induced by convergent shock wave

作　　者：党子涵 郑纯 张焕好[1] 陈志华[1] Dang Zi-Han;Zheng Chun;Zhang Huan-Hao;Chen Zhi-Hua(National Key Laboratory of Transient Physics,Nanjing University of Science and Technology,Nanjing 210094,China;School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China)

机构地区：[1]南京理工大学,瞬态物理国家重点实验室,南京210094 [2]南京理工大学机械工程学院,南京210094

出　　处：《物理学报》2022年第21期223-235,共13页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12072162,12102196);江苏省自然科学基金(批准号:BK20210322);中国博士后科学基金(批准号:2022M711642)资助的课题。

摘　　要：基于可压缩多组分Navier-Stokes方程,结合5阶WENO(weighted essentially non-oscillatory)格式以及结构化自适应网格加密技术,数值研究了汇聚激波冲击不同初始扰动幅值和气层厚度的双层SF重气柱界面不稳定性演化过程,揭示了界面与激波结构相互作用及演变机理,定量分析了环量、混合率及湍动能的变化规律,并对涡量进行动模态分解.结果表明:初始扰动幅值较大的条件下,气层内界面内外均形成马赫反射结构并在中心发生多次激波聚焦,激波穿透外界面后环量增速更大,内界面“尖钉”“气泡”更早发展,内外界面幅值与混合率增速更大.气层厚度较大时,透射激波在重气柱内移动时相位发生改变,使得内界面波峰向外发展而波谷向内发展.气层厚度较小时,内界面生成“尖钉”“气泡”较晚且不明显.通过动模态分解可以发现:耦合效应弱时,低频弱增长的动模态决定了主干结构,低频弱增长的动模态决定了主干结构上正负涡量的交换,而高频弱增长的动模态决定了界面上正负涡量的快速交换.Based on Navier-Stokes equations,combining the fifth-order weighted essentially non-oscillatory scheme with the adaptive structured grid refinement technique,the interactions between converging shock and annular SFlayers with different initial perturbation amplitudes and thickness are numerically investigated.The evolution mechanism of shock structure and interface are revealed in detail,and the variations of the circulation,mixing rate and turbulent kinetic energy are quantitatively analyzed.The dynamic mode decomposition method is used to analyze the dynamic characteristics of the vorticity.The results show that in the case with large initial perturbation amplitude,the transmitted shock wave forms Mach reflection structures both inside and outside of the inner interface of SFlayer,and multiple shock focusing phenomena occur in the center.After the transmitted shock wave penetrates the outer interface,the circulation increases faster,and the“spike”and“bubble”structure on inner interface develop faster,so that the amplitude of the inner and outer interfaces and the gas mixing rate increase.As for the case with larger thickness of the gas layer,the phase of the transmitted shock wave changes inside the layer,which forms“bubble”at the crest of the inner interface and“spike”at the trough.When the thickness of the gas layer decreases,the crest of the inner interface does not move inside after being impacted,and“spike”and“bubble”are generated in the late stage.The dynamic modes show that the main structure of vorticity and the exchange of positive and negative vorticity on the main structure are determined by the modes with weak growth and low frequency,but the modes with weak growth and high frequency determine rapid exchange of positive and negative vorticity at the interface in the cases with weak coupling effect.

关 键 词：汇聚激波 双层重气柱 RICHTMYER-MESHKOV不稳定性 

分 类 号：O354.5[理学—流体力学]