Zonal improved delayed detached-Eddy simulation of vortex generator jets at high Reynolds numbers for aeronautical flows

摘要

The present paper aims at a numerical concept for simulating pneumatic active flow control devices in aeronautical flows. The numerical approach simulates the effect of vortex generator jets (VGJ's) via chimera grids using Reynolds-averaged Navier-Stokes equations (RANS) and zonal detached-Eddy simulation (DES). The numerical results with active flow control over the flat plate and two-element DLR-F15 high-lift airfoil are validated against the experiments at chord-based Reynolds number upto Re_x = 7.67 × 10~6 and Re_x = 2.0 × 10~6 for flat plate and airfoil, respectively. The flat plate results showed that the use of DES model predicts the peak vorticity, turbulent transport, and flow dynamics of the vortex quite well at the expense of computational effort compared to the RANS approach. Numerical Unsteady RANS (URANS) simulations showed a positive effect of the VGJ's on the lift curve that lead to abrupt leading edge stall, whereas wind tunnel data that included tunnel side-wall effects indicate a more gentle stalling process. The zonal DES computations confirmed the stalling behaviour observed with URANS. At the highest angle of attack both approaches show growing cross flow separations that result from the common flow up behaviour between the longitudinal vortices.