Cavitation flow and blade loading characteristic in impeller tip region of axial flow pump

In order to take into account the local density of gas-liquid mixing area in cavitation flow field in impeller tip region of axial flow pump, the turbulent viscosity term in SST k-ω turbulence mode was corrected. NPSH curves, cavitation characteristic and blade loading were analyzed based on full cavitation model with simulation and experimental methods. The investigation results show that the modified SST k-ω turbulence model and cavitation model can predict the cavitation flow field with gas-liquid two-phase flow in the impeller tip region, and the relative error of the critical cavitation number between experimental and predicted values is 7.79% under design conditions, which is satisfactory for the computational accuracy. The high speed phohography experiments show that the cavitation inception is induced by blowing cavitation, clearance attached cavitation and tip leakage vortex cavitation, and the cavitation region continually spreads with the decrease of cavitation number. The break of cavitation bubble cluster occurs at the aft of the blade, and the position of bubble break moves toward the middle of the blade span. The angular interval between (13° and +13° is the main region of the suction side with low pressure. Within the 3% area attached to the blade tip clearance, the pressure gradually decreases with the increase of radius coefficient r*, decreasing the blade surface loading. Near the tip clearance, the blade loading decreases more obviously. © All Rights Reserved.