Design of Adaptive Transonic Airfoils By Means of Numerical Optimization
A. Sommerer, Th. Lutz and S. Wagner
Proceedings ECCOMAS 2000: European Congress on Computational Methods in Applied Sciences and Engineering, September 11-14, 2000, Barcelona, Spain
In the context of efforts made in order to reduce wave drag while flying at transonic Machnumbers, investigations were carried out regarding the mechanisms of the shock control bump (SCB). An introduction to the physics of the SCB explains how wave drag reductions can be achieved by means of isentropic compression waves. Since the bump has to be properly positioned and shaped to generate a favourable effect, critical geometrical parameters were investigated in the present paper using numerical optimisation tools. An optimisation environment was developed consisting of a hybrid optimiser, a geometry module and an efficient analysis tool, namely an Euler solver, coupled with an integral boundary layer method. For a specified off-design flight condition bump shapes were optimised. The influence of various geometric bump representations was investigated. With respect to an adaptive bump, shape optimisations were performed for different design Machnumbers but identical lift coefficient. To overcome the problem of narrow Mach-regions of optimum drag reduction for one-point designed bumps, multi-point designs were utilised in addition.