Investigation of hydraulic transient flow and dynamic response performance of axial pump based on novel vibration signals characteristics and numerical analyses

Simulation studies were conducted to investigate structure of internal flow and pulsation in pressure properties of pumps under different flow circumstances. An empirical model for shear-stress transport turbulence was also used to investigate how tip leakage vortices affect turbulent flows. Experiments were conducted in order to validate CFD results for accuracy and reliability. The study found that the vortex at the tip of the internal flow affects the pressure difference between blade surfaces, thereby altering the clearance flow and tip leakage vortex. Additionally, the study observed unsteadiness near the surface and extra suction due to secondary flow besides vortices tip leakage upstream of suction wall. Depending on the inlet pressure, axial flow pumps have different pulsation characteristics. Pulsation amplitudes near the impeller are high because blade passage frequency is high. In small flow conditions, clearance backflow causes significant pressure fluctuations at blade tip of axial pumps. The pump frequency and amplitude decrease as flow increases. Simulations model tests showed that the amplitude pressure of impeller pump is significantly larger under low flow conditions, where there is substantial backflow clearance owing to pump having a large clearance.