泵站正向进水前池底坎整流机理数值模拟

为研究正向进水前池存在的不良流态,基于N-S方程和Realizable k-ε紊流模型,采用SIMPLE算法,数值模拟了正向进水前池中无任何措施和增设底坎整流措施的流态.CFD计算结果表明：原方案的前池两侧出现了大面积的回流区,泵站两侧机组进水条件差,水流偏斜较为明显;加底坎,且当底坎离进水池较远时,整流效果并不明显,前池内仍有大面积的回流产生,偏流依然严重;当底坎离进水池较近时,坎后旋涡直接影响到进水池的流态;通过CFD优化,底坎设在离进水池入口（7~10）D处,能明显改善前池的流态,水流能较均匀地流入各台机组;随着底坎坎高的增大,底层回流区会逐渐变小,较大回流区发生的位置也由坎后变为坎前,坎高的取值约为0.3H＇时,前池内流态较好;底坎的顶宽尺寸对前池流态的影响较小.CFD计算结果与试验结果基本吻合,研究成果对正向扩散前池流态改善有借鉴价值和实际意义.

Numerical simulation of mechanism for sill rectifying flow in pumping station intake

To eliminate vortices in a pumping station intake,the flow patterns in the intakes without and with a sill in their bottom were simulated based on the incompressible N-S equations,Realizable k-ε turbulence model and SIMPLE algorithm.It was shown that there were large recirculation zones in both sides of the intake without a sill and the main stream was obviously off the central line and shifted to one side,causing unbalance flow rate in both sides.For the intakes with a sill,the large recirculation zones still existed if the sill was placed further away from the intake outlet and the main stream kept to be shifted one side considerably as well.If the sill was moved to the intake outlet closer,the vortices shed from the sill could disturb the flow pattern near the outlet straightforward.When the sill was located at the distance（7-10） D away from the intake outlet,then the flow pattern was improved significantly,leading to the flow rate distributed uniformly into each pump suction pipe.The downstream recirculation zone at the bottom of the sill kept shrunk until it disappeared at all with increasing height of the sill,eventually,an upstream recirculation zone occurred.It was illustrated that a better flow pattern was achievable with the height of approximate 0.3H＇.Note that the top width of sill had a less effect on the flow pattern.The predicted flow patterns were in good agreement with the measure-ments.These outcomes can be useful for flow pattern improvement in pumping station intakes with expanding width towards the intake outlet,but also has practical significance.