An example of the research carried out by DSRI is shown below . It concerns acoustics and aerodynamics of swarm of drones .
The flight of unmanned aerial vehicles ( UAVs ) and swarms of UAVs will become increasingly present in the environment , including urban areas . Quadcopter drones , in particular , have been witnessing a considerable market demand during the last five years , thanks to the variety of their applications and affordable cost . As a result , quadcopter drones have been invading new emerging sectors such as agriculture , entertainment , energy , construction , surveillance , law enforcement , and delivery . Quadcopter drones can be of different sizes , but the majority are small to medium . They can fly thanks to the four propellers system . The propeller system is made of an electric motor that rotates a propeller made of multiple blades ( two or more ) that provide the fuselage ’ s lifting force ( or drone ’ s structure ). Today , quadcopters are massively produced at low costs and in different shapes and sizes , ranging from some centimeters to some meters .
One of the critical questions in the research and development of next-generation drones is designing silent drones with a low sound noise level . Having quieter drones is very important for environmental noise reduction with an impact on human health . To achieve the above , we need to advance our understanding of noise emanating from drones and swarms .
Bird swarms that travel in a specific geometric formation have always fascinated people , such as V-shape ( see figure on the left ). We have studied a swarm of quadcopter drones and their aeroacoustic noise generation and shown that the V-shape flight formation could halve the noise in the best human hearing frequency range .
Steady state velocity field around a swarm of drones moving at 9 m / s in the flight direction . ( a ) V-shape flight formation ; ( b ) U-shape flight formation .
Noise level prediction around a swarm of six quadcopter drones . The V-shape flight formation emits less noise compared to the U-shape flight formation .
Studies published by T . Dbouk and D . Drikakis , Physics of Fluids , American Institute of Physics , 2021 . https :// doi . org / 10.1063 / 5.0052505