Numerical simulation of unsteady flow in centrifugal pump volute

Unsteady flow characteristics in a centrifugal pump volute were investigated by using duel time stepping method in the numerical simulation. The simulation results indicated that 'jet/ wake' phenomenon was identified near the impeller. The configuration of the 'jet/wake' was varied from inlet to outlet in the volute. The wake center was located at about 10% of the impeller passage behind suction side at the central region of the volute and about 20% at the cutwater region. Simulation results showed that static pressure fluctuation was mostly affected by blade-tongue interaction, and dynamic pressure fluctuation was mostly influenced by the 'jet/ wake' flow structure. When the flow rate was lower than the designed flow rate, static pressure increased from inlet to outlet in the volute. When the flow rate was higher than the designed flow rate, static pressure decreased from inlet to outlet in the volute. Additionally, the position of tongue stagnation point moved outside into inside of tongue with the flow rate increased.