Prediction of noise from interaction of vorticity with airfoils using CAA

Abstract

The long-term objective of the research is to use computational aeroacoustics (CAA) to assess the source mechanism, generation and propagation of airframe noise. As one step towards this purpose, the noise which is caused by the interaction of vorticity waves with the leading edge of real airfoils is simulated using CAA. The perturbation equations about the mean flow are used as governing equations in solving this problem. In order to create accurate results and keep a minimum number of grid points, a non-uniform grid system is used in which local resolution enhancement is achieved by stepping the grid size of neighboring grid blocks by factors of two. In the area of two Cartesian grid interfaces, a combination of Tam & Webb's DRP and Lele's cell-centred high order differencing scheme are implemented. A direct Cartesian boundary treatment of curved-wall is implemented. Joukowski airfoils with different thickness are chosen in the simulation. The influence of the airfoil thickness and the airfoil profile on radiated noise is described.