Study On Hydraulic Performance Of A Pump Sump With Two Suction Pipes In Line With Flow

The thesis serves as a partial fulfillment of the requirement of Doctor Degree. It could also be regarded as the report of a research project of the "Study on Hydraulic Performance of a Pump Sump with Two Suction Pipes in Line with Flow" arising from the requirement of planning optimization of pump sump of nuclear/thermal power plants. The main object of this study is to get a better understanding of the complicated three-dimensional flow characteristics of the water intaking originated from two sources arranged in series and to get a scientific background to prove the availability and limitation of such pipes arrangement.Both experimental investigation and numerical simulating were conducted. The main aspects of the work proceeded and the results could be summarized as follows:(1) Systematic experiments were carried out in a 4.5 m ×0.32 m×0.6 m glass flume with two intaking pipes of diameter D = 8 cm spacing L apart in line with incoming flow. Hydraulic behaviors of the water intaking including the formation of air-entraining vortex were attentively observed with the relevant formula for predicting critical submergence depth presented. Under the same water depth and the same intaking discharge but with different (L/D), detailed X-Y, Y-Z, X-Z plane velocity fields were measured by PIV (Particle Image Velocimetry) and carefully analyzed. It has been demonstrated the remarkable high-3D and high-unsteadness of the flow in the water region between the pipes under certain conditions; the high dependence of (L/D) to the flow uniformity and steadiness into the pipe; the hydraulic response of the 2-intaking pipes placed in series could be accepted if L > 3D .(2) The complicated 3D flow with free surface of the same water region concerned were mathematically simulated by a CFD model, which solves the Reynolds averagedNavier-Stokes equations with the RNG k-e turbulence model and VOF model to treat the boundary of free surface. Thorough comparisons of the calculated results with the corresponding measured values show their good agreement in whole.The numerical modeling gives the same conclusions drawn from the parametric experiments. Studies on lower water level were extended.