2. Mach number(马赫数) 定义:流体某一点的运动速度和该点当地声速之比,以M表示 Definition: the mach number m is the ratio of the flow speed c to the velocity of sound in the same fluid at the same state. it is denoted as m Varieties of flow(流动的种类): M<1 subsonic flow(亚声速流 M=1 sonic flow(声速流 M≈1 transonic flow(临界流) M>1 supersonic flow(超声速流) M>>1 hypersonic2. Mach number (马赫数) 定义：流体某一点的运动速度和该点当地声速之比, 以M 表示 Definition: The Mach number, M, is the ratio of the flow speed, c, to the velocity of sound in the same fluid at the same state. It is denoted as M. Varieties of flow (流动的种类): M<1 subsonic flow (亚声速流) M=1 sonic flow (声速流) transonic flow (临界流) M>1 supersonic flow (超声速流) M>>1 hypersonic a c M = M  1