Investigation into the Effects of Blade Tip Twist on Noise Reduction for a NACA 0012 Rotor Blade

Abstract

The advancement of the urban air mobility concept is heavily dependent on the public acceptance of the aircraft vehicles used for air taxis. The importance of the perception of noise by humans is crucial to the passing of legislation and proposals working to implement the new transport system. The investigation into how the noise perception can be reduced is vital to the success of the personal air travel industry. The air taxi design has been geared towards the rotorcraft models. Therefore, the investigation into the rotor blade designs is necessary because, similar to helicopters, the main component in noise generation is the rotors and its blades. The blade-vortex interaction creates noise which humans perceive as the most annoying and disruptive type of noise produced by rotorcraft. The blade-vortex interaction noise is due to the interaction between the advancing blade and the vortexes generated by the tips of the previous rotor blade. This study looks into the effect of tip twist on rotor blades. Understanding how twist in a blade will affect thrust production and noise production will aid in the progress of developing the acceptance of the urban air mobility movement. This investigation is carried out through the use of high-fidelity rotorcraft modeling software developed by Continuum Dynamics Incorporated called the Comprehensive Hierarchical Aeromechanics Rotorcraft Model (CHARM) coupled with the aeroacoustic processing package PSU-WOPWOP to produce sound data files at the wake of the rotor blades. The noise reducing parameter under investigation is the tip twist of the rotor blades. Particularly, interest is on how this change affects the frequency of sound pressure levels. The reduction of this type of noise will aid in determining the design of efficient and safe air taxis that will utilize a system of smaller porting stations as drop off zones, similar, only in concept, to those ride-sharing services.