Effect of Volute Tongue-impeller Gaps on the Unsteady Flow in Mixed-flow Pump

The three-dimensional steady and unsteady numerical method was applied to simulate the flow in the mixed-pump with different volute casings. The base circle diameters of three volute casings were 280 mm,290mm and 300mm,the characters of the pressure fluctuation were obtained with different base circle diameters. The results show that the pressure pulsation presented an obvious periodicity. At the same flow rate,the smaller the radial clearance,the larger frequency domain of pressure fluctuation at each monitoring point. The fluctuation amplitude near the volute tongue is larger than other points. For the mixed-pump with 290mm volute base circle diameters its performance experiments and numeric simulations were done. The calculated results are in good agreement with measurement results. Numerical simulation is believable.