基于流场数值模拟的蜗壳优化改造

Improvement of Spiral Case Based on Numerical Simulation of Flow Field

针对以等速度矩设计的混流式水轮机蜗壳在含泥沙水流中长期运行时尾段磨蚀严重的问题,提出型线优化方案,利用数值模拟方法对改型前后的水轮机全流道进行数值验证,结果表明改型后的蜗壳鼻端速度降低,减小了磨蚀对水轮机的破坏。通过对比分析蜗壳改型前后的速度矩、速度切向分量平均值及液流出流角的变化规律,得到一种工程中切实可行的蜗壳抗泥沙磨损及提高水力性能的改造方案。实例应用表明,该改造方案有效可行,可在工程中推广应用。

Aiming at the problem that the tail section of spiral case of Francis turbine designed by the constant velocity moment generates serious abrasion in the long run of the silt flow,the contour optimization scheme is proposed.The numerical simulation method is used to verify the whole flow path of the turbine before and after the modification.The results show that the velocity of the end of spiral case after the modification is reduced and the damage to the turbine is reduced.The change law of velocity moment,velocity tangential component and liquid flow angle were compared and analyzed before and after renovation.A feasible scheme to improve spiral case hydraulic performance and anti-abrasion is obtained in practice.Case study shows that the improved scheme is effective and feasible,and it can be popularized in engineering.