Global-optimization-based methods for use in boundary layer transition control

Turbulent flow has a significantly higher drag than the corresponding laminar flow at the same flow conditions, and therefore incurs a significant penalty of increased fuel consumption due to the extra thrust required. One possible way of decreasing the drag is to apply surface suction to delay the transition from laminar to turbulent flow. In this paper an aerofoil with three non-overlapping panels covering up to 20 per cent of chord for boundary layer transition control is considered. The problem is complicated by the fact that panels can change both their positions and lengths. The complexity of the optimization problem is such that it is not practical to perform the investigation using a single processor. A constrained global parallel algorithm based on a combination of deformed configuration methods and a controlled random search method is developed. It is shown that for the problem considered, good solutions can be found efficiently.