Effect of blade top clearance on semi-open fuel pump performance and leakage vortex

In order to reveal the fuel pump performance and leakage vortex characteristics under different blade top clearances, three schemes with blade top clearances of 0.1 mm, 0.2 mm, and 0.3 mm are chosen in this paper to reveal the fuel pump performance and leakage vortex characteristics under various blade top clearances. The SST k-omega turbulence model is then used to numerically simulate the semi-open fuel pump and analyze the fuel pump external characteristics, leakage vortex structure, motion trajectory, formation mechanism, blade pressure loading, and entropy generation rate in the impeller. The results demonstrate that as the blade top clearance increases, the hydraulic performance of the fuel pump decreases and the area of the separated vortex area in the blade top clearance area increases; at phi = 0.3 mm, the fuel pump's efficiency is about 6% less efficient than at phi = 0.1 mm; under all three blade top clearances, there are two leakage vortices, TLV1 and TLV2, with TLV1 having the most influence on the flow pattern in the main flow area. the pressure coefficient difference Delta C-p is the greatest near the leading edge of the blade, leading to the formation of TLV here; from the blade inlet to outlet, TLV motion trajectory gradually away from the blade suction surface, and as the blade top clearance becomes larger, the motion trajectory deviates from the blade suction surface more, which is mainly caused by the Koch force term in the vortex transport equation; entropy generation rate and TLV distribution location are basically the same, mainly distributed in the blade suction surface side. The closer the blade top clearance area, the higher the entropy generation rate; the larger the blade top clearance, the larger the distribution area of high entropy generation rate, the stronger the mechanical energy dissipation effect in the fuel pump.