Numerical simulation and design optimization on flow passage of underground pump station
LI Jiazhen1*, WANG Tao1, XUE Xingzu2, GUO Yongxin1, FU Hui1, JI Changzhi3
1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; 2. Jilin Province Water Resources and Hydropower Consultative Company, Changchun, Jilin 130021, China; 3. China Three Gorges Construction Engineering Corporation, Chengdu, Sichuan 610023, China
Abstract：Taking the flow passage of an underground pump station as a case study, the numerical si-mulation model was established. The hydraulic performance and defects of designed layout was analyzed, 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 2.30-2.45, while the flow velocity distribution uniformity and velocity weighted average angle are 95%-97% and 86.5°-87.5°, respectively. 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 water 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. Not only the hydraulic performance is improved, but also the excavation and lining of pressure tank is avoided. The research results can serve as guidance for other similar projects.
