大型泵站正向前池防淤优化模拟研究

Simulation study of preventing sedimectation in front inflow forebay at large-scale pumping station

针对从多沙河流取水的大型泵站前池泥沙淤积问题,以甘肃省景电灌区内大型正向泵站前池为研究对象,利用Fluent软件基于ICEM-CFD软件构建的原型前池结构三维模型对直边正向与曲边正向前池水流流态进行了模拟分析,探索了造成前池泥沙淤积的原因和机理,提出了采用压水板改善流态的前池泥沙淤积防治措施,并模拟了直边正向与曲边正向前池不同压水板参数组合的防淤效果.结果表明：泵站前池水流形态数值模拟结果与实际运行情况一致,平面和立面扩散较差,主流效应严重,泥沙淤积主要分布在前池内两侧流速较低的回流区,由直边正向前池改造形成的曲边正向前池泥沙淤积有所减少,但仍存在大面积回流区;在泵站前池内设置45°压水板可增强水流横向扩散度,增大扩散速度,使得直边正向和曲边正向前池两侧回流区范围和强度减小,减少了泥沙淤积;引入流速分布均匀度指标,对压水板整流前后泵站前池内的流速分布均匀度进行了分析,验证了增加合理的整流措施可以有效改善前池流态;由于曲边前池端机组取水空间狭窄,使得水泵进水条件较差,削弱了45°压水板的整流效果.本研究成果可为同类泵站工程前池的更新改造和优化设计提供参考和依据.

For the sediment deposition problems of the large-scale pumping station forebay that getting water from the sandy river;choosing the large-scale pumping station front inflow forebay in Jingdian Irrigation District in Gansu province as a typical representative area;using the ICEM-CFD software to build a 3 D model of forebay prototype structure and Fluent software to simulate its flow regime;including the front inflow forebay and the curved-edge front inflow forebay;to explore the reason and mechanism of sediment deposition in the front inflow forebay;and put forward the measures of using depressed plate to improve the flow pattern to prevent sedimentation.Meanwhile;the effect of silt prevention of the two types of front inflow forebay with different parameters of water pressure plate is simulated.The study results show that the numerical simulation of the flow regime of pumping station forebay is consistent with the actual operating conditions.The surface diffusion and vertical diffusion of the water flow is poor and the mainstream effect is serious;the sediment deposition mainly distributed in low velocity recirculation zone onboth side of the forebay.Sediment deposition of the curved-edge front inflow forebay has been reduced which is formed by the front inflow forebay;but there is still a large area of the recirculation zone;lateral diffusion of water flow can be enhanced by set the 45°water depressed plate in pumping station forebay;and increasing the speed of diffusion;it can significantly reduce the range and intensity of the recirculation zone on both sides of the forebay and the amount of sediment deposition.The velocity distribution uniformity index is introduced to analyze the velocity distribution uniformity in the forebay of the pumping station before and after using the water pressure plate.It is proved that the reasonable rectifying measures can effectively improve the flow pattern of the forebay.However;due to the space is narrow;pumps at both end＇s inlet conditions are poor;and rectifier effect of the 45°pressure water plate are weaken.The study results can provide reference and basis for the renovation and reconstruction and the optimization design of the similar project of pumping station forebay.