Unsteady Simulation of Transonic Buffet of a Supercritical Airfoil with Shock Control Bump

Abstract

The unsteady flow characteristics of a supercritical OAT15A airfoil with a shock control bump were numerically studied by a wall-modeled large eddy simulation. The numerical method was first validated by the buffet and nonbuffet cases of the baseline OAT15A airfoil. Both the pressure coefficient and velocity fluctuation coincided well with the experimental data. Then, four different shock control bumps were numerically tested. A bump of height h/c = 0.008 and location xB/c = 0.55 demonstrated a good buffet control effect. The lift-to-drag ratio of the buffet case was increased by 5.9%, and the root mean square of the lift coefficient fluctuation was decreased by 67.6%. Detailed time-averaged flow quantities and instantaneous flow fields were analyzed to demonstrate the flow phenomenon of the shock control bumps. The results demonstrate that an appropriate “λ” shockwave pattern caused by the bump is important for the flow control effect.

Experimental Characterization of Upper Trailing Edge Flaps for Transonic Buffet Control

“…With this device the quasi-normal shock wave is replaced by a λ-shaped shock wave, with the working principle extensively described by Bruce and Colliss (2015). Colliss et al (2016); Ogawa et al (2008) have confirmed that an array of 3D SCBs is more efficient than a 2D bump configuration (which spans along the full span of the model as described in detail by Zhang et al (2021)) in view of the streamwise vortices developing from the tail of the bumps. Applications of the use of SCBs for controlling buffet are discussed in the numerical studies of Mayer et al (2018) and Geoghegan et al (2020), which confirmed the dependence of the performance of a SCB on its size, shape and position relative to the shock.…”

Closed-Loop Control of Transonic Buffet Using Active Shock Control Bump

“…Jacquin et al [3] performed the buffet experiment on the OAT15A airfoil section in the ONERA S3Ch transonic wind tunnel and developed an extensive experimental database for the validation of numerical buffet simulations. It was found that the most promising approach was using high-fidelity Reynolds stress models and higher-order methods which can capture essential flow physics, such as detached-eddy simulations by Deck [4], Grossi et al [5], Zhang et al [6], and Huang et al [7]. However, such techniques are currently not practical for exploring a large parameter space due to their extremely high computational cost.…”