Unsteady flow computations of a slat with a blunt trailing edge

A detailed computational study of a high-lift configuration was conducted. The unsteady Reynolds Averaged Navier-Stokes (RANS) computations focused on the accurate simulation of the local flow field of a slat having a blunt trailing edge. At a slat deflection angle of 30 degrees relative to the main element, the simulations reveal the presence of strong vortex shedding at the slat trailing edge. The resulting flow unsteadiness produces large amplitude propagating waves. The local spatial resolution of the computed solution is sufficiently fine to capture the nearfield structure and propagation direction of the generated sound. The calculated shedding frequency is in good agreement with the measured acoustic frequencies obtained at NASA Langley's Low Turbulence Pressure Tunnel. At a lower slat deflection angle of 20 degrees, the computation suggests that the shedding process is severely damped and that no waves propagate, in agreement with the acoustic measurements.