Experimental Study on Vortex Shedding in Water Medium of Closed Three-Way Side Branch Pipe
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摘要: 通过对封闭三通旁支管水介质下漩涡脱落现象进行研究，根据其三通管道漩涡脱落产生机理，建立了封闭三通旁支管试验装置进行机理验证。采用粒子图像测速（PIV）试验手段，获取不同流动工况下封闭三通旁支管三通位置处截面流线、速度等，分析了三通管道漩涡脱落产生的位置及其变化特征。试验结果表明：由于三通管道特有的流场结构会导致在三通位置形成压力波，在旁支管道内形成漩涡；在流体流经主管道与旁支管道的交界区域会产生很大速度梯度，导致在旁支管道前缘位置形成不断脱落的小漩涡团；由于流体粘性作用，旁支管道前缘流体会被主流区域流体带动向下游流动，在前缘位置产生真空区域；主管道与旁支管道交界面速度波动、旁支管道内的漩涡大小、旁支管道前缘的漩涡脱落速度均会随着流速的增加而 增大。Abstract: Through the study on the vortex shedding in the water medium of the closed three-way side branch pipe, and according to the vortex shedding mechanism of the three-way pipe, a test device for the closed three-way side branch pipe is established to verify the mechanism. The Particle Image Velocimetry (PIV) test method is used to obtain the cross-sectional streamlines and velocities at the three-way positions of the closed three-way side branch pipe under different flow conditions, and analyze the location and change characteristics of the vortex shedding of the three-way pipe. Tests have shown that due to the unique flow field structure of the three-way pipe, a pressure wave will be formed at the location of the three-way, and a vortex will be formed in the side branch pipe; a large velocity gradient occurs in the area where the fluid flows through the main pipe and the side branch pipe, resulting in the formation of a small vortex that is falling off at the front edge of the side branch pipe; due to the viscosity of the fluid, the fluid at the front edge of the side branch pipe will be driven by the fluid in the main flow area to flow downstream, creating a vacuum area at the front edge; the velocity fluctuation at the interface between the main pipe and the side branch pipe, the size of the vortex in the side branch pipe and the vortex shedding velocity at the front edge of the side branch pipe will increase with the increase of velocity.
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Key words:
- Three-way branch pipe /
- Vortex shedding /
- PIV test /
- Water medium
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图 4 不同时刻流速云图及流线图
Figure 4. Flow Velocity Cloud Diagram and Streamline Diagram at Different Moments
图 5 不同截面下x轴方向速度分量
Figure 5. Velocity Component in x-axis Direction under Different Sections
图 6 不同截面y方向流速分量
Figure 6. Flow Velocity Component in y Direction under Different Sections
图 9 流场仿真与PIV实验对比图
Figure 9. Comparison between Flow Field Simulation and PIV Experiment
表 1 试验工况
Table 1. Test Conditions
工况 1 2 3 流量/(m3·h−1) 1.36 1.56 1.74 流速/(m·s−1) 0.36 0.41 0.46 雷诺数 11465 13057 14649 帧率 1000 1000 1000 
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表 2 计算参数设置
Table 2. Calculation Parameter Setting
类型 参数名 参数值 模型尺寸 入口段长度/mm 736.5 出口段长度/mm 283.5 旁支管高度/mm 403 湍流模型 DES SST k-w 边界条件 速度入口/(m·s−1) 0.42 压力出口/Pa 0 操作压力/Pa 101325 入口湍流强度/% 5 Δt/s 0.0001
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