The flow with solid-liquid two-phase media inside centrifugal pumps is very complicated and the relevant method for the hydraulic design is still immature so far. There exist two main problems in the operation of the ...The flow with solid-liquid two-phase media inside centrifugal pumps is very complicated and the relevant method for the hydraulic design is still immature so far. There exist two main problems in the operation of the two-phase flow pumps, i.e., low overall efficiency and severe abrasion. In this study, the three-dimensional, steady, incompressible, and turbulent solid-liquid two-phase flows in a low-specific-speed centrifugal pump are numerically simulated and analyzed by using a computational fluid dynamics （CFD） code based on the mixture model of the two-phase flow and the RNG k-~ two-equation turbulence model, in which the influences of rotation and curvature are fully taken into account. The coupling between impeller and volute is implemented by means of the frozen rotor method. The simulation results predicted indicate that the solid phase properties in two-phase flow, especially the concentration, the particle diameter and the density, have strong effects on the hydraulic performance of the pump. Both the pump head and the efficiency are reduced with increasing particle diameter or concentration. However, the effect of particle density on the performance is relatively minor. An obvious jet-wake flow structure is presented near the volute tongue and becomes more remarkable with increasing solid phase concentration. The suction side of the blade is subject to much more severe abrasion than the pressure side. The obtained results preliminarily reveal the characteristics of solid-liquid two-phase flow in the centrifugal pump, and are helpful for improvement and empirical correction in the hydraulic design of centrifugal pumps.展开更多
Flow characteristics of both oil and water in a horizontal pipe are the basic information for the design of crude oil transportation and production profile logging.The flow characteristics are more complicated when oi...Flow characteristics of both oil and water in a horizontal pipe are the basic information for the design of crude oil transportation and production profile logging.The flow characteristics are more complicated when oil or water carries sediment particles.In order to simulate the distribution of flow characteristic parameters of water-or oil-sediment mixture in a horizontal pipe,the governing equations and the boundary condition for the mixture phase of water-or oil-sediment were established by the mixture algebraic slip model (MASM) based on the Eulerian description method,and the numerical solution was obtained by the finite difference method and successive over relaxation (SOR).The simulation results indicated that the mainstream velocity moved downwards with increasing volume fraction of the particle phase and decreased with reducing pressure drop.The distributions of the volume fraction of the particle phase in the circular cross section were related to the mainstream velocity,and the volume fraction values increased downwards and sidewards with reducing mainstream velocity.Moreover the mainstream velocity of the oil-sediment mixture phase was larger than that of the water-sediment mixture phase.The mixture algebraic slip model could well simulate the flow characteristic parameters of the mixture phase with higher computing efficiency.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 21076198)Zhejiang Provincial Natural Science Foundation of China (Granted No. R1100530)National Basic Research Program of China (973 Program,Grant No. 2009CB724303)
文摘The flow with solid-liquid two-phase media inside centrifugal pumps is very complicated and the relevant method for the hydraulic design is still immature so far. There exist two main problems in the operation of the two-phase flow pumps, i.e., low overall efficiency and severe abrasion. In this study, the three-dimensional, steady, incompressible, and turbulent solid-liquid two-phase flows in a low-specific-speed centrifugal pump are numerically simulated and analyzed by using a computational fluid dynamics （CFD） code based on the mixture model of the two-phase flow and the RNG k-~ two-equation turbulence model, in which the influences of rotation and curvature are fully taken into account. The coupling between impeller and volute is implemented by means of the frozen rotor method. The simulation results predicted indicate that the solid phase properties in two-phase flow, especially the concentration, the particle diameter and the density, have strong effects on the hydraulic performance of the pump. Both the pump head and the efficiency are reduced with increasing particle diameter or concentration. However, the effect of particle density on the performance is relatively minor. An obvious jet-wake flow structure is presented near the volute tongue and becomes more remarkable with increasing solid phase concentration. The suction side of the blade is subject to much more severe abrasion than the pressure side. The obtained results preliminarily reveal the characteristics of solid-liquid two-phase flow in the centrifugal pump, and are helpful for improvement and empirical correction in the hydraulic design of centrifugal pumps.
文摘Flow characteristics of both oil and water in a horizontal pipe are the basic information for the design of crude oil transportation and production profile logging.The flow characteristics are more complicated when oil or water carries sediment particles.In order to simulate the distribution of flow characteristic parameters of water-or oil-sediment mixture in a horizontal pipe,the governing equations and the boundary condition for the mixture phase of water-or oil-sediment were established by the mixture algebraic slip model (MASM) based on the Eulerian description method,and the numerical solution was obtained by the finite difference method and successive over relaxation (SOR).The simulation results indicated that the mainstream velocity moved downwards with increasing volume fraction of the particle phase and decreased with reducing pressure drop.The distributions of the volume fraction of the particle phase in the circular cross section were related to the mainstream velocity,and the volume fraction values increased downwards and sidewards with reducing mainstream velocity.Moreover the mainstream velocity of the oil-sediment mixture phase was larger than that of the water-sediment mixture phase.The mixture algebraic slip model could well simulate the flow characteristic parameters of the mixture phase with higher computing efficiency.
