混流式水轮机空化流动特性分析

采用混合物空化模型对混流式水轮机的内部流场进行了数值计算,得到了大流量工况、最优流量工况、小流量工况水轮机的内部流动特性。计算结果表明：在大流量工况和小流量工况下,尾水管中心截面的低压区与涡带是相对应的,压力脉动的幅值主要受尾水管涡带直径两端压力差的影响,其尾水管进口段左右两侧以及弯肘段附近均有较大的漩涡区域,造成较大的能量耗散,尾水管内有明显的回流现象,水轮机内部流动比较紊乱。

Cavitation Characteristic Analysis of Francis Turbine

A mixture cavitation model for francis turbine internal flow was developed,and the numerical calculation was carried out.As a result,the internal flow characteristics of high flow condition,the optimal flow conditions and low flow condition turbine were obtained.The results showed that in the high flow conditions and low flow conditions,the low pressure area of the draft tube center section corresponded to the vortex.The amplitude of the pressure fluctuation was mainly affected by the pressure difference of the draft tube vortex diameter ends.There was large whirlpool area at the ends of the tube inlet sides and near the elbow segment.It caused larger energy dissipation and reflow phenomenon in the draft tube and disorder in the turbine flow.