水轮机过流部件出水边夹角对卡门涡频率的影响

Influence of Outlet Edge Angle of Hydro Turbine Flow Passage Components on Karman Vortex Frequency

利用数值模拟方法,模拟具有相同出水边厚度、不同出水边夹角的一组水轮机过流部件下游侧的卡门涡现象,研究出水边夹角对卡门涡频率的影响,结果表明,随着出水边夹角的增加,卡门涡频率逐渐降低;当出水边夹角增加到30°时,卡门涡频率模拟值大约降低到圆柱绕流卡门涡频率理论公式计算值的1/3。通过对数值模拟结果和理论公式计算值进行对比分析以及数据处理,获得斯特劳哈尔数与过流部件出水边夹角的关系曲线和近似的直线拟合公式。以某水轮机固定导叶出水边卡门涡振动测试数据为基础,对比验证水轮机过流部件卡门涡数值模拟方法的准确性,以及获得的斯特劳哈尔数取值计算公式的准确性。研究结果对合理设计水轮机过流部件出水边形状、避免发生卡门涡共振问题具有较高的指导意义和参考价值。

Karman vortex phenomenon near downstream side of a group of hydro turbine flow passage components with same outlet edge thickness and different outlet edge angle is simulated, by using numerical simulation method. Influence of outlet edge angle on Karman vortex frequency is studied. The results show that Karman vortex frequency decreases with an increasing outlet edge angle. Karman vortex frequency obtained by numerical simulation method decreased to one third as compared with the one obtained by using Karman vortex frequency theoretical formula for flow around circular cylinder, when outlet edge angle is increased to 30° . Based on the comparison between results of numerical simulation and values obtained by theoretical formula, and data processing, Relation curve and approximate linear fitting formula between Strouhal number outlet edge angle of flow passage components are obtained. By compared with the test data of Karman vortex vibration of stay vane outlet edge of an hydro turbine, accuracy of Karman vortex numerical simulation method for hydro turbine flow passage components is validated, and Strouhal number calculation formula is also validated. The research shows great significance in optimal shape design of outlet edge of hydro turbine flow passage components and avoiding vibration induced by Karman vortex.