Abstract:An ejecting self-priming centrifugal pump of type UJM75-2 with additional water baffle was selected as test model to improve the pump self-priming performance.The influencing rule of the added water baffle at the back of the diffuser on gas phase flow capacity in the pump chamber was analyzed by using a combined experimental validation and numerical simulation method. Furthermore, the mechanism that the water baffle influences ejecting self-priming pump performance was studied based on the analytical results.The results indicate that the outflow of the mixed fluid is affected by the relative position between the outlet holes above the baffle and the ribs at the back of the diffuser, and the optimal installation position existes. When the liquid flowes to the pump chamber from the outlet holes, it has a scouring effect at the pump outlet, leading to an insufficient gas-liquid separation, and in consequence, a part of the liquid enteres the pump discharge pipe to block the gas to be discharged.When the angle between the symmetric center line of the outlet holes and the center line of the pump outlet is 90°, the experimental self-priming height is up to 8.5 m and the self-priming time is 3 min. The pump with the water baffle shows a little difference in performance in comparison with that without the baffle. Thus, the baffle can improve self-priming performance under stable operational conditions.