Aerodynamic and Aeroacoustic Performance of an Isolated Multicopter Rotor During Forward Flight

The forward flight stage of multicopters accounts for a relatively large amount of flight time in comparison with hovering, ascending, and descending conditions; therefore, understanding its aerodynamic and aeroacoustic performance is significant for preliminary design, aerodynamic optimization, and control methodologies. By setting different rotation speeds, shaft angles, and freestream velocities according to realistic operation conditions, an investigation of a full-scale isolated rotor in a low-speed anechoic wind tunnel is conducted. When the freestream velocity increases and the shaft angle decreases, the thrust, power, moments, and sound pressure level (SPL) of the rotor increase by maintaining the same rotation speed. Through appropriate normalization methods, the loading coefficients and SPL collapse to one surface with respect to the advance ratio and shaft angle, and third-order polynomials are applied to fit nondimensional data. Using the fitted polynomials, power consumptions and noise emissions for generating the required lift during the level flight are calculated from different parameter combinations, and optimal solutions are suggested.