Experimental investigations on aerodynamic and psychoacoustic characteristics of three-blade looprop propeller

Abstract

Aeroacoustic noise in multiple rotor drones has been increasingly recognized as a crucial issue. This study focuses on addressing this challenge by introducing a novel low-noise looprop propeller design with three blades. Unlike traditional propellers, the looprop propeller utilizes three closed-loops to generate thrust. Through comprehensive experimental investigations conducted in an anechoic chamber using a hover stand test, we conducted an integrated study of the propeller's aerodynamic, aeroacoustic, and psychoacoustic characteristics. The results demonstrate that the three-blade looprop propeller achieves a notable reduction in the overall sound pressure level (OASPL), particularly in tonal noise at the blade passing frequency where the tone reduction amounts to approximately 15 dB. Additionally, we employed Zwicker psychoacoustic annoyance models to evaluate the propellers' psychoacoustic performance and discussed the environmental noise mask effect. The findings indicate that the three-blade looprop propeller exhibits an improved sound quality while maintaining aerodynamic performance comparable to that of conventional propellers. Overall, our study suggests that the looprop propeller design offers significant advancements in acoustic performance, particularly in terms of psychoacoustic characteristics. These findings hold promising implications for the field of drone technology and the potential for notable improvements in noise reduction.