Aerodynamic and aeroacoustic characterization of an axial fan using Adaptive Mesh Refinement (AMR) based CFD and CAA

Abstract

This work focuses on numerical analysis of a low-pressure axial fan using Computational Fluid Dynamics (CFD) and Computational Aeroacoustics (CAA) methods. These simulations are performed with the commercial software Hexagon's Cradle scFLOW. The investigation focuses on flow prediction using incompressible Large Eddy Simulation (LES), and acoustic propagation based on the Ffowcs Williams-Hawkings (FW-H) equation. We present a method to evaluate the mesh resolution for LES and a mesh refinement approach to resolve strong flow interactions, particularly near the tip-gap region. Both the aerodynamic and aeroacoustics performance of the fan are compared to experimental measurements for model validation. The pressure rise, velocity profiles and surface pressure fluctuations are captured well. Similarly, the sound propagation results are in good agreement with the experimental measurements. At low-mid frequencies, the blade passing frequencies and subharmonic peaks are captured, and at high frequencies, the broadband energy content is underpredicted, but still reasonably correlated. Additionally, a discussion regarding the mesh quality for LES is presented.