Comparative assessment of propeller noise prediction methods against flyover data

Abstract

This study presents a noise prediction toolchain for propeller aircraft, specifically designed for application in early preliminary design phases. Thereby, novel propeller aircraft designs can be provided with low-noise capabilities, and optimal landing and takeoff trajectories as well as the impact on the communities of such aircraft can be investigated. Two aerodynamic modeling approaches for propeller load prediction are compared: a simple blade element method and a full 3D aerodynamic model. This data is furthermore processed and provided as input for the noise prediction. Based on these results, the study evaluates tonal noise predictions from Hanson’s and Farassat’s models against flyover noise measurements of a Do 228 aircraft under various operating conditions. The comprehensive study assesses model performances across different velocity regimes. Key findings reveal that unweighted maximum sound pressure levels increase with both airspeed and rotational speed. Flight speed significantly influences the radial position of the thrust peak, shifting it outward from approximately 65–85% of the blade radius as speed increases. However, this outward shift does not significantly affect tonal noise emission. While both noise models successfully predict the velocity trend, simulations consistently underpredict noise levels by 3 dB to 5 dB compared to experimental data.