Generalised Modelling of Sound Signatures for Characterization of Multi-copter Unmanned Air Vehicles based on Aero-acoustics Measurements and CFD Analysis

Abstract

In this research work, the aim is to characterize the aero-acoustic signature of multi-copter Unmanned Air Vehicle based on the FW-H acoustic analogy. Characterization of single propeller sound signature and quad-copter’s sound signature has been done, so that the two sound signatures can be compared and generalized characterization for every multi-copter UAV configuration can be formalized. An unstructured grid has been used. The flow is being simulated by using Large Eddy Simulation, and FW-H acoustic analogy is being utilized in the ANSYS Fluent® environment to estimate the acoustics levels at the specified receiver locations. An aero-acoustic signature pattern is recognizable based on a tonal frequency which is a function of Blade Passing Frequency (BPF) and the number of propellers being used on the respective configuration of the multi-copter UAV. Sound pressure varies logarithmically in every direction with distance and shows asymmetrical behavior on a radial plane downstream of the quad-copter, however, the behavior is nearly symmetric for a single propeller