Numerical simulation and design optimization on flow passage of underground pump station
Taking the flow passage of an underground pump station as a case study,the numerical si-mulation model were established.The hydraulic performance and defects of designed layout was ana-lyzed,moreover,the optimal layout was presented.The results show that the flow separation occurres at the entrance of inlet pipe in the designed layout,which resultes from the large intersection angle of 70° between the inflow direction and the connection line from the center of inlet pipe entrance to that of the circular tunnel outlet.The head loss coefficient reaches 2.31-2.44,while the flow velocity distribu-tion uniformity and velocity weighted average angle are 95.09%-96.80%and 86.51°-87.41°,respec-tively.The pressure tank connectes the foregoing circular tank using sudden expansion cross-section and the following inlet pipe using abrupt contraction,without any guidance structure,which lead to large head loss coefficient.The optimal layout adoptes manifold tube and branch pipes to distribute wa-ter flow and two 60° elbows to offset the flow.There is no sudden expansion or contraction structure,and the head loss coefficient is largely reduced to 0.93-1.07.The hydraulic performance is improved,and the excavation and lining of pressure tank are avoided.The research results can serve as guidance for other similar projects.