桨叶穿孔对轴流转桨式水轮机性能的影响

Effect of Blade Perforation on Performance of Kaplan Turbine

以某电站轴流转桨式水轮机为研究对象,在桨叶进口边布置5个直径为4 mm的微孔,研究了叶片穿孔对轴流转桨式水轮机性能的影响。采用SST k-ω湍流模型对桨叶进口边未穿孔和穿孔的水轮机进行了单相流稳态数值模拟计算,并在此收敛的基础上结合Mixture混合模型和Zwart空化模型进行气液两相流瞬态计算。根据数值模拟结果分析了穿孔前后桨叶吸力面负压区及空泡的面积分布、转轮体内的空泡体积及涡量分布、尾水管进口处监测点的压力和水轮机效率等的变化。结果表明:本文所选用的多相流及空化模型能较好地模拟转轮的空化情况;该打孔方式能有效减少转轮内的空化面积和涡量,且对尾水管进口处的压力脉动影响不大;此种打孔方式不会对水轮机效率产生影响。

The Kaplan turbine is taken as the research object,and five pores with diameter of 4mm are arranged at the blade inlet to study the effect of blade perforation on the turbine performance.SST k-ω turbulent model is used to do steady numerical simulation of single-phase flow in the turbine with and without perforation at the blade inlet.Based on the convergence,the transient numerical simulation of gas-liquid two-phase flow is carried out by combining the Mixture and Zwart model.The negative pressure zone,bubble area,cavitation bubble volume and vorticity distribution in runner,efficiency and the pressure at the draft tube inlet are analyzed.The results show that the multiphase flow and cavitation model can well simulate cavitation.The blade perforation can effectively reduce the cavitation and vorticity in runner,and has little effect on the pressure fluctuation at the inlet of draft tube and the efficiency of turbine.