DIRECT NUMERICAL SIMULATIONS OF FLAP SIDE EDGE NOISE

Direct numerical simulations of noise generation and radiation from aircraft flap side edges are performed in the presented paper. The objective of this work is to identify the generating mechanism of flap side edge noise. A CFD/CAA approach is taken in which the mean flow field around a three element high-lift system is provided by RANSICFD calculations and the unsteady flow field involving shear layer instability waves and acoustic waves is calculated by a linearized Euler/CAA method. The high accuracy DRP finite difference scheme with PML boundary conditions is used to guarantee the accuracy of the unsteady calculations. A multi-domain, multiple time step technique is used to enhance the efficiency of the calculations. The computed results indicate that the feedback/interaction among side-edge shear layer instability waves is the dominant noise generating mechanism.