Optimised propeller geometries for low broadband noise

Karimian, Amin, Joseph, Phillip and Paruchuri, Chaitanya (2023) Optimised propeller geometries for low broadband noise. In Proceedings of the AIAA Aviation 2023 Forum: Propeller, Rotorcraft and V/STOL Noise I: Isolated Rotors. American Institute of Aeronautics and Astronautics.. (doi:10.2514/6.2023-3219).

Abstract

This research presents an experimental investigation of the far-field acoustic properties of propellers with varying pitch values. The study delves into the underlying physical principles governing noise source mechanisms in propellers based on pitch values. The classical propeller Broadband noise model was validated and used as an objective input for a genetic algorithm optimization process. The aim was to evaluate the propeller's turbulent Boundary Layer-Trailing Edge interaction Broadband noise and reduce it. Optimizations were carried out on two blade section profiles, targeting broadband noise reduction and boundary layer thickness, while maintaining aerodynamic properties within a 10% increase compared to the baseline propeller blade. As a result, a low noise propeller geometry profile was achieved, with minimal aerodynamic deviations from the baseline. Notably, significant broadband noise reduction was observed in the mid-frequency range (100 Hz to 3 KHz), accompanied by a shift in the peak of the Broadband spectrum to higher frequencies. The overall sound power level of the optimized propeller was reduced by 3 dB compared to the baseline, achieved through geometric alterations to the upper and lower airfoil surfaces, and the reduction of Boundary Layer thickness and wall shear stresses at the Trailing Edge.

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Contributors

Author: Amin Karimian

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