Evaluation of Acoustic Frequency Methods Coupled to Blade Element Momentum Theory for the Prediction of Propeller Noise

The accuracy of several computationally-inexpensive acoustic frequency methods is evaluated across a range of propeller geometries and operational conditions. The acoustic models considered do not require chord-wise aerodynamic data and therefore do not need to be coupled to a panel or grid-based aerodynamic solver. Each implemented method is compared to fourteen test cases originating from nine separate published acoustic experiments. The experimental data considered encapsulates a range of propeller geometries, blade numbers, microphone locations, tip speeds, and forward Mach speeds. The implemented acoustic models demonstrate good agreement with the experimental data, particularly for the prediction of the maximum tonal noise for which the model based on Hanson's helicoidal surface theory of propellers has an average error of 7.2 dB. The presented results suggest that the implemented acoustic methods remain a valuable resource for propeller noise prediction, especially for design and optimization studies, where a low runtime is important.