长短叶片混流式水轮机全流道内部流场数值模拟研究

Numerical Simulation of the Internal Flow Field in Full Flow Channel of Francis Turbine with Long and Short Blades

为研究某电站长短叶片混流式水轮机内部流动特性,利用仿真模拟软件CFX,基于N-S方程和标准k-ε湍流模型,在典型小流量工况下,对水轮机蜗壳进口到尾水管出口的全流道内部流场进行三维湍流计算,得到水轮机各过流部件的流动情况。计算结果表明,蜗壳内静压分布沿向心方向均匀降低,速度矢量均匀增大。导叶间速度和压力在圆周方向对称性良好,进出口无明显漩涡。长短叶片表面压力分布合理,工作面无明显回流及二次流。尾水管内流线顺畅,呈中心对称分布,速度沿向心方向均匀减小。各流线回旋形成较为对称的涡带,且涡带中心无偏移,管内无明显回流。研究结果对该水电站水轮机日后运行维护具有重要的指导意义。

In order to study the internal flow characteristics of a Francis turbine with long and short blades after the transformation of a hydropower station,the three-dimensional turbulence is calculated for the internal flow field of the full flow passage from the inlet of the turbine casing to the draft tube. The method is based on the N-S equation and the standard k-ε turbulence model under the condition of typical small flow,and the numerical simulation is carried out by using the simulation software CFX to obtain the flow of each flow component of the turbine. The calculation results show that the distribution of static pressure in the volute decreases uniformly along the centripetal direction,and the velocity vector increases uniformly. Vortex guide vane speed and pressure in the circumferential symmetry is good,and there are no significant vortex in the suction side and the outlet section. The length of the blade surface pressure distribution and the work surface no significant backflow and secondary flow. The flow lines in the draft tube are smooth and centrosymmetrically distributed,and the velocity decreases uniformly along the centripetal direction. Each streamline formed a more symmetrical vortex,and the center of the vortex without offset and no significant backflow tube. The research results have an important guiding significance for the future operation and maintenance of the hydropower station turbine.