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用实验方法测量了非对称阶跃扩张管道中湍流分离区的三维速度分布。测量是用自制的双差动型声-光频移二维激光测速仪完成的。管道扩张比为2:1,展高比为3:2,实验雷诺数为5700。在分离区紧靠台阶的下游,测得了一对展向涡,涡心位置随高度略有变动。沿展向再附点的位置也不同,在中心截面再附长度最大,接近两侧壁时分离区有缩小趋势。用激光可视化技术得到了回流区和展向涡的流动图形,与激光测速的定量结果很一致。
The three-dimensional velocity distribution of the turbulent separation zone in the asymmetric step-expansion pipe was measured experimentally. The measurements were made with a self-made dual-differential acousto-optical frequency shift 2D laser gun. The pipeline expansion ratio is 2: 1, the aspect ratio is 3: 2, and the experimental Reynolds number is 5700. Immediately downstream of the step in the separation zone, a pair of vortices was observed, with the vortex position slightly varying with height. The location of reattachment points along the exhibition is also different, with the maximum re-attachment length in the center section. The separation area tends to decrease when approaching the two side walls. The laser flow visualization technique was used to obtain the flow patterns of the recirculation zone and the vortex-shedding vortex, which was consistent with the quantitative results of laser velocimetry.