Influence of blade profile on energy loss of sewage self-priming pump

Abstract

Sewage self-priming pumps are widely used in municipal sewage treatment and agricultural irrigation. The impeller is the key component to determine the hydraulic performance of sewage self-priming pump. In this study, the ZW100-100-15 sewage self-priming pump was selected as a research object. Five double-channel impellers with different blade profiles were designed based on the same meridional shape. The ANSYS CFX 16.2 and shear stress transport k–ω turbulence model were conducted to investigate the sewage pump models with five different impellers numerically. The entropy production theory was applied to analyze the internal energy losses of different sewage pump models. The mechanism of influence of blade profiles on the energy losses was investigated systematically. The results indicated that under different flow rate conditions, the hydraulic efficiency of S5 scheme with a concave blade angle distribution profile is higher than that of other schemes. At the design flow rate, the head of S5 was the highest, the flow state inside the impeller was the most stable and the energy loss inside the impeller was the least. In non-design conditions, the flow distribution and entropy production rate distribution of S5 were significantly better than those of other schemes. Results illustrated that flow separation, backflow, shock effect, vortex and rotor–stator interaction were the main inducers for the formation of entropy production. This research indicated that the entropy production theory can predict the irreversible energy loss in pump accurately and the blade profile optimization can effectively improve the sewage self-priming pump hydraulic performance and weaken the unstable flow and its internal energy loss.