Exploring the effects of phase delay on propeller noise: an experimental study in tandem configuration

Noise cancellation is a revolutionary control strategy, so effective that it has been integrated into high-end headphones. Implementing this approach on drones may seem challenging, but at the same time, it is highly appealing. The idea is to use some rotors, which constitute the main noise source, as a secondary pressure wave to eliminate the noise emitted by the entire propulsion system by inducing destructive interference among the individual sources. Implementing this kind of technology requires a significant understanding of the interaction mechanism of pressure waves emitted by the blades. The associated signature is not sinusoidal and exhibits strong directivity. This article will clearly demonstrate the potential of this approach by focusing attention not only on the effects but also on the nature of the interference mechanism. This finding is pivotal for the design of an active noise control system.