Design and numerical analysis on an axial-flow model pump with high specific speed

Abstract

An inverse method based on the model of radial equilibrium equation and 2-D panel method is used to design the axial-flow model pump with high specific speed. The numerical simulation is based on the CFX-TASCflow CFD code solving the 3-D RANS equations with the RNG k-ε model of turbulence. The multiple frame of reference capability (stage method) is applied to model the interaction between the impeller and guide vane as well as the grid embedding is used to simulate the tip clearance. The experimental results show the design method can assure design characteristic of the pump. A comparison of the calculation and the measurements demonstrates a very good agreement of the head and hydraulic efficiency at design point, but a significant departure at off-design point. The calculation also shows the negative thrust has turned up when the head is still positive, which exactly explain why the impeller is raised at high flow rate.