Aerodynamic Analysis of Rotor Higher Harmonic Control Using a CFD Technique

Abstract

This paper shows the results of aerodynamic and acoustic analysis of rotor higher harmonic control (HHC) using a CFD technique. HHC is one of the techniques for rotor blade-vortex interaction (BVI) noise reduction. A moving overlapped grid method is applied in the CFD code and three types of grid, inner and outer background grids, and blade grid are used to accurately simulate the blade-vortex interaction (BVI) phenomena. The calculated model is a single-blade rotor and the experimental data was obtained by the cooperative work between JAXA and Kawada Industry. In this calculation, the frequency of HHC is 20Hz (2/rev), and the amplitude is ±2.6°. 72° and 250° of control phase angles are chosen. These phases are selected for the weak BVI noise case and strong BVI noise case in the wind tunnel test, respectively. Our CFD code well captured the HHC effect on the blade surface pressure and acoustic waveform. However, the tendency of computed noise with respect to the control phase shows the reverse tendency compared with experimental results.