混流式转轮的性能预估和增容优化

Performance prediction and power capacity expansion of Francis runners

通过对原型混流式转轮的三维定常湍流计算,找出导致水轮机出力达不到设计要求的原因,根据计算结果对原型转轮提出增容优化改造建议,对改造后的转轮性能进行预估,以验证增容优化改造方案的可行性.流场计算以连续方程和雷诺时均N-S方程为基础,选用标准k-ε两方程湍流模型使方程组封闭,通过贴体坐标下的有限体积法对控制方程进行离散,数值求解采用SIMPLIC算法.计算结果表明,增容优化改造后的水轮机转轮流场分布较为合理,满足电站水力参数的要求,改造方案可行.此方法也可推广到转轮水力设计中.

Through 3-D stationary turbulence calculation of a prototype of Francis runner, the origin of its output deficiency from the design requirements of the turbine was found. According to the calculation result, a suggestion of optimization remodelling of its blades were proposed in order to expand the power capacity of the prototype and the performance of new runner was predicted to verify the correctness of the remodelling method. The calculation process was based on the continuity equation and Navies-Stokes equation. The standard κ-ε two-equation turbulence model was used to make the equation group closed. The control equation was discretized by using finite-volume method and solved numerically with SIMPLIC method. The calculation result of new runner indicated that the distribution of flow field in the remodeled runner was more reasonable, so that the requirement of hydraulic parameters of the power plant was met and the remodeling scheme was proved to be feasible. This procedure could also be extendedly used in the hydraulic design of the runner.