NUMERICAL OPTIMISATION OF ADAPTIVE TRANSONIC AIRFOILS WITH VARIABLE CAMBER

A special research group (SFB 409) has been established at Stuttgart University to investigate the potential of adaptive structures for aerospace application. One project deals with concepts and aerodynamics of adaptive transonic wings. To cope with the problem of flight at transonic Mach numbers adaptive mechanisms are introduced. Aerodynamic efficiency at off-design conditions is improved by the application of a shock control bump (SCB) on a variable camber (VC) airfoil. Since a SCB has to be properly shaped and positioned to generate a favourable effect, relevant geometrical parameters were investigated using direct numerical optimisation. An optimisation environment was developed consisting of a hybrid optimiser, a geometry module and a coupled Euler boundary-layer code. For a specified offdesign condition bump shapes were optimised, while the influence of various geometric bump representations was investigated. Shape optimisations for an adaptive bump were carried out for different Mach numbers at a fixed lift coefficient. To overcome the problem of narrow Mach regions of significant drag reduction for one-point designed bumps, multi-point designs were performed. Finally a VC-SCB combination was numerically optimised in order to improve the performance for several off-design conditions.