Effect of Mach number on transonic flow past a circular cylinder  

作　　者：XU ChangYue CHEN LiWei LU XiYun 

机构地区：[1]Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026, China

出　　处：《Chinese Science Bulletin》2009年第11期1886-1893,共8页

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 90405007, 90605005);Science and Technology Innovative Foundation of Chi-nese Academy of Sciences (Grant No. CXJJ-237)

摘　　要：The effect of Mach number on transonic flow past a circular cylinder is investigated numerically for the free-stream Mach number M∞ from 0.85 to 0.98 and the Reynolds number 2×105 based on the diameter of the cylinder. The work provides an insight into several salient features, including unsteady and quasi-steady flow state, formation of local supersonic zone, and evolution of turbulent shear layer. Results show that there exist two flow states dependent of a critical Mach number Mcr around 0.9. One is an unsteady flow state characterized by moving shock waves interacting with the turbulent flow in the near region of the cylinder for M∞<Mcr, and the other is a quasi-steady flow state with nearly sta-tionary shock waves formed in the near wake for M∞>Mcr, suppressing vortex shedding from the cylin-der. Some flow behaviors in the unsteady and quasi-steady flow states are revealed. From time evolu-tion of flow structures, local supersonic zones are identified in the wake and generated by two typical processes, i.e. reverse flow behind the cylinder and shed vortices in the near wake. The convective Mach number Mc of turbulent shear layers shed from the cylinder is identified nearly as Mc<1 in the unsteady flow regime and Mc>1 in the quasi-steady flow regime, resulting in different evolutions of the shear layers.The effect of Mach number on transonic flow past a circular cylinder is investigated numerically for the free-stream Mach number M∞ from 0.85 to 0.98 and the Reynolds number 2×10^5 based on the diameter of the cylinder. The work provides an insight into several salient features, including unsteady and quasi-steady flow state, formation of local supersonic zone, and evolution of turbulent shear layer. Results show that there exist two flow states dependent of a critical Mach number Mcr around 0.9. One is an unsteady flow state characterized by moving shock waves interacting with the turbulent flow in the near region of the cylinder for M∞〈Mcr, and the other is a quasi-steady flow state with nearly stationary shock waves formed in the near wake for M∞〉Mcrs, suppressing vortex shedding from the cylin- der. Some flow behaviors in the unsteady and quasi-steady flow states are revealed. From time evolu- tion of flow structures, local supersonic zones are identified in the wake and generated by two typical processes, i.e. reverse flow behind the cylinder and shed vortices in the near wake. The convective Mach number Mc of turbulent shear layers shed from the cylinder is identified nearly as Mc〈I in the unsteady flow regime and Mc〉I in the quasi-steady flow regime, resulting in different evolutions of the shear layers.

关 键 词：马赫数 圆柱体 绕流 非定常流动 湍流流动 时间演化 稳态流动 剪切层 

分 类 号：O357.1[理学—流体力学] V43[理学—力学]