Reducing the noise of Micro-Air Vehicles in hover

Abstract

Micro-Air Vehicles (MAV) are becoming common devices in a wide range of operations while the optimization of their propulsion system is rarely addressed. On the one hand, an aerodynamic optimization would have a straightforward effect on the endurance. On the other hand, an aeroacoustic optimization might increase discretion in military operating conditions, reduce noise pollution in civilian, urban environment and allow sound recordings in dual applications. This contribution aims at presenting a complete methodology for the design of silent and still efficient rotors for MAV, from aerodynamic prediction to aeroacoustic optimization and experimental validation. This approach is suitable for engineering purposes. The aerodynamic and acoustic modeling are described and the optimization procedure is presented. A step-by-step optimization is achieved and measured on an experimental bench suitable for non-anechoic environment. A discussion on the results is proposed. Key parameters on the blade geometry for the reduction of rotor noise are provided at the end of the paper.