Numerical Analysis of Cavitation Flow in Low Specific Speed Condensate Pump Impeller

The low specific speed condensate pump has the characteristics of high head, small flow, large outer diameter of the impeller and low efficiency.However, during cavitation, the head is reduced, the efficiency is reduced, and the noise is increased significantly.This paper takes 105-34-1500 type condensate pump as the research object.Based on numerical calculation and experimental method, the flow rule of cavitation in condensate pump impeller is studied.The results show that at 0.6 times design flow, with the inlet pressure decreases, the cavitation on the suction surface of the blade is significantly larger than the cavitation on the pressure surface and there is a significant fracture cavitation occurs in the volute. At the design flow rate, significant gap cavitation occurs in the volute with the inlet pressure decreases. At 1.4 times the design flow, the cavitation is intensified and fills the entire flow path. With the pressure decreases, the cavitation zone on the pressure surface gradually disappears, and there is obvious cavitation at the exit of the volute. This phenomenon causes the pump characteristic curve to drop faster, and this condition should be avoided as much as possible.