一、引言如所周知,六十年代国外在圆柱绕流的实验研究中,将卡门涡街现象引伸至管流(三元流动)而得到如下公式:f=S_o(V/D)式中f——圆柱障碍物一侧旋涡出现的频率;v——流体受阻前的自由流速;D——阻流圆柱的直径;S_t——比例系数,即斯脱罗哈尔数(strouhal)。由于Re在600～300000之间St近于常数,所以在一定管径下,v和f存在比例关 I. INTRODUCTION As we all know, in the 1960s abroad, in the experimental study of circular cylinder flow, the phenomenon of Karman vortex extends to pipe flow (ternary flow) and got the following formula: f = S_o (V / D) where f V - the free flow rate before the fluid is blocked; d - the diameter of the choke cylinder; and S_t - the proportionality factor, which is the strouhal. Since Re is close to a constant between 600 and 300000 St, so under a certain diameter, there is a ratio of v to f