Aeroacoustics of Coaxial Co-Rotating Propellers: Experimental Analysis and Mid-Fidelity Prediction

This work investigates the advantages and limitations of fast turnaround methods for the prediction of the aerodynamic performance and tonal noise emissions of coaxial co-rotating propellers. An extensive aeroacoustic experimental campaign has been performed to confirm the trends highlighted in previous literature, further investigate the relation between propulsive efficiency and noise emissions, and provide a database for the validation of the numerical methodology. A surface panel method is used to predict the aerodynamic coefficients. The pressure distribution on the blade surface is used to predict the tonal noise using a rotating dipole formulation. This combination of numerical tools successfully predicts the trends observed experimentally and can thus be used in optimization studies involving phase offset angle and axial separation distance, allowing a fully virtual preliminary design of co-rotating propellers.