泵站超大扩散角压力前池立柱阵列整流的优化设计

受场地布置尺寸的限制,山东省黄水东调二期工程加压泵站压力前池的扩散角度达到78.8°,大大超出正常前池扩散角的范围。根据该站不同运行工况时的压力前池三维流场数值模拟分析结果,该站压力前池内因扩散角过大而导致存在大范围的回流区,对水泵安全稳定运行构成严重威胁。为了使该站在前池扩散角很大的情况下能够为水泵进口提供较为理想的流态、保证水泵正常运行,采用基于Navier-Stokes方程和标准k-ε湍流模型的CFD方法,利用该站压力前池内的数十根结构支撑立柱,在压力前池控制尺寸不变的条件下,采用立柱排列与前池侧壁边界型线调整相配合的技术方案,进行了前池整流优化研究。研究结果表明:前池整流优化方案消除了该站大扩散角压力前池原方案中的大范围回流区和喇叭管附近的紊乱流动,各工况下水流能够较为平顺地流向喇叭管;各工况下喇叭管出口的流速分布均匀度平均值均不低于98%,水流角度平均值均不小于87°,可为水泵运行提供符合要求的流态;结构复核计算结果表明压力前池优化方案2能够满足柱体结构强度和顶板变形的要求。该泵站前池已按本文研究结果实施,泵站建成后的实际运行情况表明,水泵机组运行安全稳定。

Optimum design of rectifying flow of column array in pressure forebay with extra-large diffusion angle of a pumping station

Limited by the size of the site layout，the diffusion angle of the pressure forebay of the booster pumping station in the Yellow River East Water Diversion Project II in Shandong Province reaches 78. 8 °，which is far beyond the range of the normal forebay diffusion angle． According to the numerical simulation results of 3-D flow fields in the forebay under different operating conditions，there were large recirculation regions because of the large diffusion angle，which has a serious threat to the safe and stable operation of pump． In order to provide ideal flow pattern for the pump inlet to ensure the pump operation normal under the condition of large diffusion angel，the CFD method based on the Navier-Stokes equations and standard k － ε turbulence model was used to calculate flow field in the pressure forebay，by using dozens of structural support columns in the pressure forebay，the optimization of the forebay rectification was carried out by adopting the technical scheme of the columns arrangement and the adjustment of the boundary profile of the forebay side wall under the condition of keeping the control size of the pressure forebay unchanged． The study results show that: the large recirculation regions and turbulent flow near the bell-mouths in the original scheme of pressure forebay are eliminated by the forebay rectification optimization scheme，so that the current can flow smoothly to the bell-mouths under all operation conditions; the average values of velocity distribution uniformity at the outlet of bell-mouth are all larger than 98% under all operation conditions，and the average values of flow angle are all larger than 87°，so that the optimization scheme can provide flow pattern for the pumps to operate satisfactorily; the results of structural review calculations show that the optimization scheme 2 for pressure forebay can meet the requirements of column structural strength and roof deformation． The forebay of the pumping station has been built according to the optimization scheme． The actual operation of the pumping station shows that the pump units operate safely and stably．