Abstract
The present study reports an experimental investigation regarding one of the most effective and most studied passive control technique in literature to mitigate the noise pollution radiating by a small drone: the Serrated Trailing Edge (STE). 23 quiet propellers have been designed and manufactured in order to identify the most silent configuration. An aeroacoustic pre-qualification of the designed propellers has been performed by means of microphone measurements within the anechoic chamber of Niccolò Cusano University. Then, an aeroacoustic and fluid dynamic characterization of the most performing configuration has been carried out by means of load cell, microphone and PIV measurements in the anechoic wind tunnel facility of TUDelft University of Technology in order to investigate the mechanism that stands behind the noise mitigation. With this purpose, the aerodynamic and aeroacoustic performance and even the velocity and vorticity field along the blade of STE propellers have been characterized. Particular attention is devoted to the fluid-dynamic aspects related to the low Reynolds number flow regime. Results show that serrations seems to modify the wake velocity and the tip voretx intensity resulting in a lower acoustic emission.
Highlights
Drones, usually referred as Unmanned Aerial Vehicles (UAVs) or Micro Aerial Vehicles (MAVs), are automatized vehicle with high manoeuvrability in both hovering and cruise operations tipically designed with vertical or horizontal take-off and landing capabilities, and can manoeuvre with extremely high versatility and speed
The present study reports an experimental investigation regarding one of the most effective and most studied passive control technique in literature to mitigate the noise pollution radiating by a small drone: the Serrated Trailing Edge (STE). 23 quiet propellers have been designed and manufactured in order to identify the most silent configuration
The reference system is centered with the propeller center, the x and y axis are normalized with respect to the propeller radius and the flow is aligned with the y axis
Summary
Usually referred as Unmanned Aerial Vehicles (UAVs) or Micro Aerial Vehicles (MAVs), are automatized vehicle with high manoeuvrability in both hovering and cruise operations tipically designed with vertical or horizontal take-off and landing capabilities, and can manoeuvre with extremely high versatility and speed. Due to their unique properties of versatility for different tasks the contexts where drones find possible application are manifold. Regardless of the specific field of use, the noise produced by UAVs is one the key aspect which is slowing down the widespread deployment of these vehicles in urban areas. Even the Wall Street Journal indicates, in an article publisched in 2018 ”Delivery Drones Cheer Shoppers, Annoy Neighbors, Scare Dogs” [2], Drone noise pollution as the main obstacle to widespread public acceptance of this technology in residential areas
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