Detached Eddy Simulation of Micro-Vortex Generators Mounted on NACA 4412 Airfoil

Abstract

Micro-vortex generators (MVGs) are simple vane-type devices installed on surfaces , i.e., aircraft wing and tail, to control boundary layer flow separation. They are cost-effective and require an efficient numerical method to resolve the embedded longitudinal vortical structure, as the flow behind them is highly unsteady. This numerical study aims at analyzing the effect of MVGs on the NACA 4412 airfoil performance using the detached eddy simulation (DES) at 60,000 Reynolds number based on the freestream velocity of 11 m/s and the wing chord of 0.1 meter. The MVGs are installed in a row in counter-rotating configuration at 10% chord of the airfoil. The DES is utilized to resolve the high energetic scales of the vortex behind the MVGs which Reynolds-averaged Navier–Stokes (RANS) is not likely to resolve properly. A comparison of DES simulations with the RANS simulations shows that RANS modeling is not sufficient to capture the airfoil flow characteristics at higher angles of attack. The DES simulations resolve the turbulent scales downstream of the MVGs effectively and produce significant improvement in NACA 4412 wing performance. It has been observed that airfoil lift coefficient at 10 deg angle of attack with the MVGs is 5% higher than the airfoil without MVGs. MVGs along the airfoil chordwise location demonstrate that MVGs at 25% chord are more effective in managing separation over the airfoil compared to those at 10% chord location.