Aeroacoustic characteristics of twin-isolated system in forward flight

This study presents an experimental investigation of the aeroacoustic characteristics of isolated-twin propeller configurations in forward flight, with a focus on the effect of the blade tip separation distance between the propeller blades. Two identical 5-bladed propellers with a diameter of D = 9” and P/D = 1 were used. Measurements were acquired at fine increments of wind tunnel speeds ranging from 8 m/s to 16 m/s corresponding to various advance ratios while maintaining a constant rotational speed of 8000 rotations per minute. The spectra and directivity of the far-field noise were studied in detail for both broadband and tonal components.