Experimental study on hydraulic performance optimization of ultra-low specific speed centrifugal pump

To improve the head and efficiency performance of an ultra-low specific speed centrifugal pump, this paper takes a marine magnetic-driven ultra-low specific speed centrifugal pump with a specific speed of 27 as the object of study. On the basis of the original model impeller with three blades, impeller A and impeller B with four blades of the same outer diameter and outlet widths of 4 and 2.5 mm were optimized and designed. Taking methanol as the medium, the impacts of factors such as the structure of the impeller, the aperture diameter of the throttling ring, and the cutting impeller outer diameter on the hydraulic performance of the ultra-low specific speed centrifugal pump are investigated. The influence of impeller structure, throttle ring aperture, cutting impeller outer diameter, and other factors on the hydraulic performance of an ultra-low specific speed centrifugal pump was explored. The study shows that the flow condition range of the original model impeller pump is very small, and the head decreases very fast, which cannot meet the design requirements; the head and efficiency of impeller A and impeller B are generally improved, but the flow or head deviates from the design condition, so it is necessary to set up a throttling ring or cut the outer diameter of the impeller to regulate the pump's operating parameters. The pump outlets were set up for the 12 and 15 mm inner diameter of the throttle ring and no throttle ring, respectively. Comparative experiments show that impeller A in the design head point using three kinds of throttle ring structure and the pump flow is greater than the design value of impeller B in the throttle ring bore diameter of 15 mm and that the pump flow and head can be achieved at the same time as the design value.