Study for the Increase of Micro Regenerative Pump Head

The effect of inlet and outlet blade angles on the performance of a micro regenerative pump was examined. The head of the regenerative pump was little increased by changing the blade angles compared with the original pump with the inlet and outlet blade angles of 0 degree. The effect of the axial clearance on the performance was also examined. The head was increased largely by decreasing the axial clearance. The computation of the internal flow was performed to clarify the cause of the increase of the head due to the decrease of the clearance. The local flow rate in the casing decreased as the leakage flow rate through the axial clearance decreased due to the decrease of the clearance. By offsetting the performance curve with the local flow rate, the effect of the clearance did not appear and it was found that the larger head in the smaller clearance was just caused by the smaller local flow rate in the casing. In the case of the smaller clearance, the smaller local flow rate caused the smaller circumferential velocity near the front and rear sides of the impeller, and the angular momentum in the casing and the head increased.