Effect of tip winglet angle on internal complex flow and aerodynamic performance of an axial fan

The effects of winglet angle on the flow characteristics in the tip clearance region of the AXF950 axial fan are studied in depth by numerical and experimental methods at different winglet angles (0°, 15°, 30°, 45°, 60°, and 90°). A comparison between the results of numerical simulations and those of experiments confirms the reliability of the simulations. The turbulent energy and tip leakage vortex area of the axial fan are effectively reduced by the winglet at the rated condition, while the uniformity of the blade surface pressure distribution is effectively improved and sharp pressure peaks are avoided at 15° and 30° winglet angles. The flow field is also influenced by the winglets at high flow conditions, which leads to lower and more uniform pressures at the leading edge. Airflow separation is mitigated and the aerodynamic performance characteristics of the axial fan are significantly improved. The application of winglets effectively suppresses the secondary flow at the blade midstream and trailing edges, whereas the area of the secondary flow region at the leading edge expands under low-flow-rate conditions. Our comprehensive analysis reveals that the aerodynamic performance of the axial fan is notably improved at a 15° winglet angle and that the application of winglets leads to a substantial enhancement of the efficiency of the fan. The effects of the winglet angle on the internal flow loss and aerodynamic performance of axial fans are elucidated, which has significant implications for the design and optimization of these fans.