Aeroacoustics Of Oscillating Airfoil Under Icing Conditions

Abstract

Ice accumulation on airfoil shapes changes the airfoil shape significantly depending on the severity of icing conditions. In rotor blades, blade profile goes under oscillation motion in forward flight. The shape change due to ice accumulation affects aerodynamic performance of the oscillating rotor blade and may risk the flight safety. Shape change of profile also affects pressure variation over the blade therefore acoustic signature is expected to change. In order to investigate possible use of acoustic signature change due to ice accretion, oscillating airfoil analyses are conducted with iced and clean profiles using Ffowcs Williams-Hawking approach. Acoustic pressure changes and frequency content are investigated. Significant sound pressure levels changes are observed at a specific frequency range at the one and two chord length distances. Sound energy is integrated at receiver locations. Comparison of sound energy for iced and clean profiles shows increasing trend with ice accumulation. Furthermore, the effect of exposure time on noise generation is explored. Horn formation is observed to change sound energy levels significantly. Changes in aerodynamic characteristics are resulted to be in line with noise generation.