Experiment on Influence of Blade Angle on Hydraulic Characteristics of the Shaft Tubular Pumping Device

Abstract

In order to understand the influence of blade angle on the hydraulic characteristics of a shaft tubular pumping device, the energy characteristics, cavitation characteristics, runaway characteristics, and pressure pulsation of the tubular pumping device under different blade angles were studied by a model test. Comparing the efficiency of the best efficiency point of the pumping device under different blade angles, it can be seen that when the blade angle is +4°, the efficiency of the best efficiency point of the pumping device is the lowest, 74.10%. When the blade angle is −4°, the efficiency of the best efficiency point of the pumping device is the highest, 79.75%. Comparing the cavitation characteristics of the pumping device under different blade angles, it can be seen that when the blade angle is −4°, the overall cavitation performance of the pumping device is the best. When the design head point is deviated, the NPSHav (Net positive suction head available) of the pump will increase. At the same blade angle, the runaway speed increases with the increase in head. The runaway speed of the prototype pump decreases with the increase in blade angle. When the blade angle is −6°, the runaway speed of the prototype pump is the largest, which is not conducive to the safe operation of the pumping station. When the blade angle is −4°, the variation law of pressure pulsation is small, and there is no abnormal pulsation. The tubular pumping device has satisfactory hydraulic performance, high efficiency, cavitation, and runaway characteristics. Therefore, the shaft tubular pumping device has wide application prospects under ultra-low head, and we recommend prioritizing it in low-head pumping stations.