Unmanned aerial systems (UAS) will radically transform our cities – alleviating traffic and accelerating mobility. But this vision of the future isn't without its challenges, both aerodynamically and acoustically.
The National Research Council of Canada (NRC) worked with Bell Helicopters to overcome some of these challenges by evaluating the acoustics of Bell's ducted axial fan, a part of the air taxi propulsion system that enables transition from a vertical takeoff or landing in to forward flight.
Noise standards for air taxis are still under development, and regulations have not yet been finalized, but Bell is aiming to limit air taxi noise to 62dBA at an elevation of 250 feet (76m).
The NRC used its 9 m Low Speed Wind Tunnel to conduct full-scale testing and evaluation of the fan, measuring its aerodynamics and acoustics at different airspeeds, geometries, angles of attack and rotor blade pitch angles. Results from the wind tunnel environment were correlated to free-air conditions.
New technologies create new challenges, and the NRC has more than 300 technical experts who can help companies overcome the hurdles they face in developing, testing and certifying new technologies.