Influence of continuous trailing-edge variable camber on aerodynamic characteristics of transonic airfoils

The influence of continuous trailing-edge variable camber on the aerodynamic characteristics of transonic airfoils is investigated. Before the continuous trailing-edge variable camber is considered, the aerodynamic drag reduction optimization design of the transonic airfoil is carried out based on the optimization design system constructed in this paper. With different constraints added, two kinds of transonic airfoils are obtained, namely the shock-free airfoil and the supercritical airfoil. Then the optimization design is conducted based on the two airfoils at different lift coefficients, by taking the deflection angle of the trailing-edge as the design variable and the minimum drag coefficient as the objective. And the effect of the continuous trailing-edge variable camber on the drag polar of these two kinds of transonic airfoils is investigated and analyzed according to the optimization results. The results of the optimization design show that the aerodynamic characteristics of the shock-free airfoil are better than those of the supercritical airfoil at the design point, but the robustness is worse. Besides, when the lift coefficient is lower than the design lift coefficient, the drag polar characteristic of the shock-free airfoil can be improved greatly with the continuous trailing-edge variable camber applied, thus the drag coefficient is reduced by up to 3.9%. However, the situation of supercritical airfoil is different. The results also demonstrate that when the lift coefficient exceeds the design lift coefficient, the continuous trailing-edge variable camber method can significantly improve the drag polar performance of both airfoils with the drag coefficients of them being reduced by 2.4%-18.1% and 1.7%-13.2% respectively.