Sound Generation from Gust-Airfoil Interaction Using CAA-Chimera Method

Kurzfassung

The sound field around a finite-span airfoil subjected to a two-dimensional periodic gust is simulated using CAA-Chimera method. The perturbation equations about the mean flow are used as governing equations in solving this problem. The Chimera methodology in conjunction with the high-order central difference DRP (Dispersion-Relation-Preserving) scheme, so called CAA-Chimera, has been employed to show the usefulness of the approach for realistic aeroacoustics problems. The body fitted grid is only used in a very narrow zone close to the curved body. The primary computational grid is a Cartesian grid. Special non-homogeneous inflow boundary conditions are derived to generate incoming disturbances with different angles of incidence. A multi-domain Cartesian grid system is used in which local resolution enhancement is achieved by stepping the grid size of neighboring Cartesian grid blocks by factors of two. In the area of two Cartesian grid interfaces, a combination of DRP and a specially optimized cell-centered high order differencing scheme is implemented not requiring any interpolations. In a systematic study the influence of different gust wave numbers and the airfoil camber on the radiated noise is described. The effect of mean flow compressibility on noise radiation is also studied.