Numerical Predictions of Tip Shape Effect on Helicopter Rotor Noise in Forward Flight.

The effect of helicopter rotor blade tip shape on overall aircraft noise level is analyzed, in forward flight conditions. The infamous HART-II experimental data is used as a base for validations. Commercially available CFD software Ansys/Fluent is used to model the flow field over rotor-body interaction with moving-deforming meshes. The blades are modelled individually to match the actual physical blade geometry and blade movement. The acoustics calculations are performed via FW-H modelling of the software. HART-II blade has a rectangular blade tip planform. Four different tip shapes are modeled and analyzed in addition to the original blade planform. Baseline case of HART-II experiment is used for the predictive calculations. The predictions show that the least sound pressure level obtained by %10 c notched tip shape having 10-degree anhedral angle with 2,23 dB(A) difference amongst other four tip shapes. [ABSTRACT FROM AUTHOR]