Algorithm development for RPAS noise propagation within a rigid walled urban street canyon

Complaints by urban and rural communities, due to the noise associated with recreational and commercial utilization of Remotely Piloted Aircraft Systems (RPAS), are expected to multiply in the near future. As part of the current efforts to guide the formulation of future regulations related to multi-rotor RPAS noise in Canada, as well as to support the development of new international standards, various numerical algorithms were developed and complimentary experimental studies were undertaken at the National Research Council Canada (NRC). The present article concentrates on the numerical algorithms developed to simulate RPAS noise propagation within a rigid walled urban street canyon, including multiple reflections, noise source signature strength and directivity, as well as atmospheric attenuation and turbulence. The input parameters for the numerical simulations consist of acoustic sound signatures for selected RPAS, measured under simulated steady hover conditions within a fully anechoic chamber at NRC, the geometrical characteristics of the urban street canyon, the positions of the noise source and the receiver, and the atmospheric conditions (temperature, relative humidity and ambient pressure). Moreover, a second set of numerical algorithms were developed to study the noise propagation allowing for diffraction by a building edge when the RPAS is parked on, or takes off from, a building roof top without a direct propagation path to the receiver. The implemented theoretical approaches, as well as the numerical results obtained for various studied configurations, are presented and discussed.