Multirotor propulsion systems are increasingly applied to lift Vertical Take-Off and Landing (VTOL) configurations. Multirotor systems are popular for small scale drones used for surveillance, monitoring, search, aerial surveying and photography. In recent years multirotor systems have been scaled up and are today typical designs for eVTOL configurations for Urban Air Mobility. A major concern with drones, and vehicles for Urban Air Mobility in particular, is their noise emission. In order to be publicly accepted, the noise of Urban Air Vehicles must be barely audible compared to the city’s background noise. Therefore, Urban Air Vehicles must be designed from the beginning to meet stringent noise standards.

The present research project investigates noise radiation and propagation (installation effect) of multirotor systems. The objective of the GARTEUR group is therefore to gain knowledge in the physics of noise generation and near-field noise propagation of multirotor systems under the influence of the installation effects and to establish tools for the noise prediction. The focus is put on rotors in steady hover and forward flight but other operating states and configurations could also be considered. POLIMI/DAER is contributing with wind
tunnel experiments as well as with numerical simulations. Both, a common validation study and a common experiment inside the action group are ongoing. The common validation study aims at evaluating and improving the prediction accuracy of different fidelity simulation methods.