使用粒子图像测速(PIV)技术对各二维开缝圆柱环流流场的动力特性进行定性及定量研究，揭示雷诺数(Re)、开缝位置角、开缝倾角及相对缝宽(s/d，s为缝隙宽度，d为圆柱直径)对环流动力特性的影响规律.获取瞬态流场、时均流场以及斯特劳哈尔数(Sr)等关键流场信息，研究开缝圆柱环流流场的结构及演变规律.结果表明：脱落涡与圆柱表面环流的此消彼长，引起120° 以及180° 开缝圆柱的吹吸效应，显著提前圆柱尾流脱落涡的耦合时间；240° 开缝圆柱的缝隙位置接近圆柱后缘，流体未达到缝隙位置时已经发生流动分离，不会形成有效吹吸效应；120° 以及180° 开缝圆柱的尾流脱落涡运动轨迹振幅较大，其流阻系数大于基准圆柱以及240° 开缝圆柱的尾流流阻系数；狭缝角α为180° ，相对缝宽为0.15开缝圆柱的尾流Sr在0.218～0.225范围内波动最小，具备最优的线性稳定性.
The particle image velocimetry (PIV) experiments are carried out to qualitative and quantitative study the flow field dynamic characteristics for different slit cylinders in order to reveal the influence of the Re, the slit position, the incline angle and width of the slit on the overall flow characteristics. The transient flow field, the time-averaged flow field and the Sr are obtained and the detailed overall flow structures and its transformation disciplines are studied. The results show that the interactions of the shedding vortex and the circumflux around the cylinder surface induce the blow-suction effect of the 120° and 180° slits, which makes the wake shedding vortex coupling happen significantly earlier. The 240° slit is close to the cylinder trailing edge so that the flow separation already happens before the fluid reach the slit, which fails to generate the effective blow-suction effect. The wake flow resistances for the 120° and 180° slit cylinders are higher because the motion trajectory amplitudes of shedding vortex are higher than that of the basic and 240° types. Sr values for the slit cylinder with α=180° and s/d=0.15 (α is the slit angle, s is the gap width, d is the cylinder diameter) are in the range of 0.218～0.225, which exhibits the strongest linear stability.
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