Numerical Simulation of Transonic Buffet on Swept Wing of Supercritical Airfoils

This paper presents transonic buffet simulations over a swept wing of supercritical airfoils with Unsteady Reynolds-Averaged Navier-Stokes (URANS) and Detached-Eddy Simulation (DES) methods. The NASA SC(2)-0714 airfoil is used as wing profile. Computations are conducted at free-stream Mach numbers from 0.72 to 0.84 for Reynolds number 45.0 × 10 based on aerodynamic chord length. Firstly, 2D NASA SC(2)-0714 airfoil buffet simulation is performed. The computational results are compared with experimental measurements. The computational code successfully predicts the time-averaged pressure distribution and shock wave motion frequency. Then a 3D supercritical swept wing buffet simulations are performed with URANS and DES approaches. The URANS approach fails to predict buffet unsteady flow for this swept wing, while the DES approach predicts buffet unsteady flow at free-stream Mach number from 0.72 to 0.84. With the DES computations, the unsteady flowfield around the supercritical swept wing, aerodynamic performance, the moving shock wave behavior, coherent structures of disturbance waves, correlations between shock wave position and pressure fluctuation, are examined and characterized. It is found that the 3D supercritical swept wing shock wave oscillation pattern is determined by streamwise disturbance wave propagation and spanwise disturbance wave propagation, the pressure fluctuations are weak near the root and tip region, but become stronger about z/b = 30%-z/b = 90% of the wing half span. Finally, the Mach number angle of attack buffet boundary is mapped out through the DES computations in the Mach number range between 0.72 to 0.84. As the Mach number increases, the buffet starting angle of attack becomes smaller.