Research on hump characteristics improvement of low-mid specific speed high-power centrifugal pump

Abstract

The hump phenomenon is a typical hydraulic instability of centrifugal pump. The hump curve is easily found on H-Q characteristic curves of centrifugal pump at low flow conditions. Hump phenomenon causes large vibration and noise and affects the unit stability of star-up process. The impeller model with specific speed ns=100 was used an initial impeller for the high-power centrifugal pump to be developed, and the meridian flow channel keep unchanged. The impeller geometry, the blade profile, blade exit edge, wrap angle, inlet blade angle were optimized to improve hump characteristics. The 3D pump model with the initial and optimized impeller were simulated to obtain the H-Q characteristic curve. The numerical simulation results show that the inlet secondary reflux is significantly weakened, energy characteristics and hump margin of the optimized impeller are obviously improved compared with the initial impeller. The optimized impeller was also tested on the model test system to verify the hump margin. The test results demonstrate that the optimized design considerably improve the centrifugal pump’s hump margin. The results of simulations and model tests verified that impeller optimization was a suitable and efficient way to enhance the hump characteristics. The result provides design reference for long-term safe and stable operation of low-mid specific speed high-power centrifugal pump.