混流式水轮机尾水管内部流场的PIV测试

TEST STUDY OF INTERNAL FLOW CHARACTERISTICS OF DRAFT TUBE OF FRANCIS TURBINE WITH PIV

以混流式水轮机尾水管为研究对象,设计构建了用于内部流场激光测量的模型水轮机尾水管试验台,对粒子图像测速仪(Panicle image velocimetry,PIV)技术测量水轮机尾水管内部流动的应用进行了实践。试验尾水管测试面由透明的有机材料制成,分别测试了在不同导叶开度下混流式水轮机尾水管的锥管段、肘管段出口、扩散段进出口不同测试位置上的瞬时速度,再通过时均处理,给出了速度、涡量及流线分布。在本试验条件下观察到锥管段内存在着与中心线垂直断面上的环形流动和小开度时子午面内的回流,肘管段和扩散段内产生了二次流,以及扩散段左右部分的流动不对称等现象。试验测量结果不仅加深了对尾水管内流动的理解,同时也为校验数值模拟结果提供了试验基础数据。

The tester of the draft tube of Francis turbine is specially designed and constructed for internal laser flow measurement model Francis turbine testing, where the testing planes of the draft tube is entirely made of transparent organic material. Instantaneous velocity is tested by PIV （Particle image velocimerry） on different guide vane opening in different positions, including the draft tube cone, the elbow and the inlet and outlet of draft tube diffusing section. By time averaged data process, the Internal-flow velocity, vorticity and distribution of streamlines are obtained. It is noted that it has round flow on radial planes, and back flow on meridian planes under different guide vane opening on the test conditions. There are secondary flow on the draft elbow and draft tube diffusing section. And moreover it is unsymmetrical on the left and fight planes of draft tube diffusing section. These experiment results not only help to understand the flow feature of draft tube, but also verify numerical simulation results of the flow of draft tube.