Identification and Analysis of Aerodynamic Sound Sources on the External Surface of an SUV

Currently, effective methods for analyzing the aerodynamic sound sources of Sport Utility Vehicles (SUVs) are still under development, and the relationship between sound sources and flow dynamics is not yet fully understood. This study presents a method for identifying multi-frequency sound dipole sources within the near-wall flow field by analyzing the relationship between unsteady flow field properties and dipole sources, thereby addressing the complex characteristics of aerodynamic sound sources on vehicle surfaces. Wind tunnel tests, along with full-scale (1:1) Large Eddy Simulation (LES) were conducted on a real SUV. The identification method was applied to analyze the location and magnitude of sound sources near the vehicle's surface. The results, validated using Acoustic Perturbation Equations (APE), indicated that the dipole sources are primarily distributed around the windward side of the front wheels, the side of the front headlights, the A pillar-rearview mirror-front side window region, and the raised structures near the chassis, accounting for more than 80% of the total sound energy. Using the Vortex Sound Equation, the study further explored the relationship between sound sources and flow field characteristics such as vortex structures, and analyzed the causes of sound dipole sources at various locations. The findings clearly demonstrate that the effect of flow separation significantly exceeds that of secondary attachment and turbulent boundary layers. The positions of flow separation and shedding vortices affect the spatial distribution of dipole sources, while variations in vorticity and velocity vectors influence the intensity of these sources.