Abstract: In order to study the influence of volute outlet position on the performance of a low specific speed centrifugal pump, the outlet position of the volute is adjusted on the premise of ensuring that the base circle of the volute, the area and shape of the first eight sections, the outlet diameter of the volute and the center height keep the same. Three types of volute A, B and C are designed respectively as a result. Based on Reynolds averaging method and RNG k-ε turbulence model, the numerical calculation of a centrifugal pump with a specific rotating speed of 46 is carried out by taking clear water as a medium. The results show that the change trend of external characteristics of the centrifugal pump is basically the same under three different outlet positions, but the highest efficiency is different from each other. At each operating condition, the efficiency of type C is higher than that of type A and B. The higher efficiency region for the three types tends to shift to heavy operating conditions. For the three types of volute centrifugal pumps, the static pressure distribution, turbulent kinetic energy distribution and streamline distribution at inlet of the impeller are roughly the same under their respective working conditions, while the three distributions in outlet of the impeller and flow passage of the volute vary greatly. It has been illustrated that changing outlet position of the volute has little effect on flow field at inlet of the impeller, but affects mainly the change of the flow field both at outlet of the impeller and in the volute channel.

Key words: centrifugal pump, volute outlet position, low specific speed, pressure fluctuation, numerical calculation