Influence of a Winglet Combined with a Groove Tip on the Performances of a Variable-Pitch Axial Flow Fan

Taking a two-stage variable-pitch axial fan as the research object, five schemes, including a single counter-flow rib layout grooved tip, are numerically simulated using the fluent software. The results indicate that, compared with the original blade tip, the total pressure rise and efficiency of the four proposed schemes have been improved to various degrees, with Scheme 4 (groove tip with double counterflow ribs) displaying the best performances. The total pressure and efficiency are increased by 113.44 Pa and 0.955%, respectively. The blade tip leakage flow is reduced to varying degrees under different schemes, according to the following order: Scheme 1, Scheme 2, Scheme 4, and Scheme 3 leading to a reduction of 7.44%, 6.46%, 5.36%, and 4.35%, respectively. Steady results are used as the initial condition for the ensuing strength check and modal analysis.