含沙水流水轮机两列导叶相对位置对活动导叶磨损的影响

Influence of relative setting position of double guide vane on abrasion of guide vane in hydraulic turbine operated in silt-laden water flow

为减轻含沙水流对水轮机活动导叶的磨蚀破坏,以比转速为150的混流式水轮机水力模型A227-46为研究对象,在分析导叶磨蚀机理的基础上,对水轮机两列导叶相对位置对活动导叶磨蚀的影响.采用CFD商用软件在含沙水流条件下分别对不同活动导叶与固定导叶相对位置的流场分布进行数值模拟计算,获得沿翼型弦长方向在导叶内外侧各选取的6个点上的压力,并换算为压力系数绘制出各布置方案的压力系数沿翼型弦长的变化曲线,得到压力分布变化规律.通过对比找出含沙水流条件下水轮机活动导叶与固定导叶周向偏置较好的相对安放位置角φsg为8°;同时,若减小两者的径向相对位置,即合理地增大活动导叶分度圆的直径,可使活动导叶区的流速下降,从而减轻泥沙磨损与空蚀破坏程度;同时,也改善了转轮的入流条件,有利于水轮机性能指标的提高.

In order to decrease the abrasion destruction of guide vane in hydraulic turbine operated in silt-laden water flow,a hydraulic model A227-46 for Francis turbine with specific speed 150 was taken as investigation as the object.Base on the analysis of the abrasion mechanism of guide vane the influence of relative setting position of the two rows of guide vane on the abrasion performance was investigated by using commercial software CFD for flow field simulation.Numerical simulation of flow field was carried out for the case of different relative setting position of stationary guide vane and movable guide vane,so that the pressure at 6 points on both the pressure water flow;and obtained the and suction sides was obtained and then transformed into pressure coefficient for plotting its variation curves and the variation pattern of pressure distribution along the streamline.After comparion of the results,it was found that the best circumferential offset angle of relative positioning of stationary and movable guide vane of hydraulic turbine φsg was 8°.Meanwhile,if the radial relative position was reduced,that is if the diameter of guide vane pitch circle was reasonably increased,the flow velocity in the guide vane area could be decreased,so that the degree of abrasion and cavitation damage degree was reduced and the flow condition of runner was improved at the same time in favor of turbine performance improvement.