Numerical prediction of the effect of free surface vortex air-entrainment on sediment erosion in a pump

Abstract

Sediment erosion through synergetic effects between free surface vortex (FSV) and particle erosion in silt-laden flow seriously affects the safe operations of pump. The purpose of this paper is to study the influence of free surface vortex entrainment on the erosion inner the pump impeller, aimed at the FSV and sediment erosion in sediment laden flow in a pump station of Yellow River, a new Eulerian-Lagrange approach was applied to simulate the sediment-laden flow by combining the Lagrange particle tracking approach and Volume of Fluid (VOF) method, followed by the application of Tabakoff model to estimate the erosion. Volume of fluid method was used to simulate the continuous flow FSV, and Lagrange method the particle trajectory. The theoretical model and filed results on site were used to verify the reliability of the proposed approach. Free surface vortex on particle motion and microscopic interactions between air and erosion were reviewed and discussed. Combined with the theoretical analysis and calculation results, the particle impact angle in the impeller was analyzed, and the erosion types were defined. Air entrainment by FSV does not directly erode the impeller components, but mainly changes the position, the local velocity and the concentration of the particles, which aggravates the sediment erosion in the impeller. Interestingly, air entrainment can reduce the surface erosion at some instantaneous moments. The present work may provide important engineering insights to resolve the erosion.

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Numerical Analysis of Water–Sediment Flow Fields within the Intake Structure of Pumping Station under Different Hydraulic Conditions

“…With the rapid development of measurement technology and CFD, the flow details and dynamic characteristics of complex 3D multiphase flow were further explored [16]. In order to analyze the erosion damage of pumping stations under the synergistic effect of free surface vortex (FSV) and sediment particles, Xijie Song et al [17] adopted the Euler-Lagrange method and Tabakoff model to simulate and discuss the microscopic interaction between the gas phase and erosion. To explore the development and evolution of the surface suction vortices in an open intake sump, X. Hou et al [18] conducted numerical simulations on the constructed intake sump model, analyzed the flow on the free surface, and determined the effects of the flow rate, Froude constant, and submergence depth on suction using the volume of fluid method.…”