Effect of UAV Configuration on Noise: Experimental Investigation and Analysis

In this paper, we conducted experiments to investigate the impact of different configurations on noise levels in Unmanned Aerial Vehicles (UAV). Specifically, we examined three key factors. Firstly, we studied the influence of the relative position between the rotor blade and the arm on noise. Secondly, we analyzed the effect of blade tip clearance on noise characteristics. Lastly, we explored the relationship between the distance and rotation direction of adjacent rotor blades and noise. Our findings revealed that the relative position of the propeller and arm had the most significant effect on noise levels. Rotor placement underneath the arm resulted in more than 3 dBA higher noise compared to placement above the arm. The primary difference between these cases was the tonal noise associated with the blade passing frequency (BPF). Interestingly, the direction of rotation between adjacent rotors did not have a substantial impact on noise levels, likely due to the tip vortex being out of reach. However, increasing the tip clearance between rotors led to a reduction in noise levels, although practical limits were observed. Based on our findings, we recommend mounting the rotor above the arm to minimize noise, although this configuration still generates more noise compared to a single rotor. By raising awareness of these factors, UAV designers can optimize their configurations for quieter operation and enhance public acceptance.