Analysis of aerodynamic and aeroacoustic performances of axial flow fans with variable winglet curvature in chordwise direction

Abstract

This study introduces a novel concept for axial-flow fans with winglets featuring gradually decreasing curvature along the chordwise direction. The objective is to mitigate the formation of leakage vortices in the gap flow region between the fan blade tip and the shroud. Two types of axial-flow fans, denoted as VR-A and VR-B, are designed, each incorporating variable winglets with differing rates of curvature reduction compared to the baseline CR fan with constant winglet curvature. The research encompasses a comprehensive approach involving computational fluid dynamics (CFD) simulations and experimental analyses. Numerical simulations employ incompressible Unsteady Reynolds-averaged Navier-Stokes (URANS) equations to capture intricate flow behaviors, while a virtual fan performance tester is used for flow performance predictions. Furthermore, the Ffowcs Williams & Hawking (FW–H) integral equation is utilized to estimate the radiated aerodynamic noise. Experimental measurements include flow performance assessments and noise evaluations, yielding data on flow rate, efficiency, and sound pressure spectrum. Comparisons between numerical and experimental results validate the numerical methods. Subsequent evaluations highlight the advantages of the VR fans over the CR fan, showing increased flow rates and reduced noise levels. These enhancements are attributed to the weakened leakage vortex in the gap flow region. The findings provide valuable insights for optimizing axial-flow fans partially covered by shrouds, offering improved flow performance and decreased noise radiation.