Optimization based control of boundary layer transition-theory and experimentation

Summary form only given. The use of suction to reduce the drag force on an aircraft will, of course, only be worth doing if the energy saved is greater than the energy required to drive the suction system. In particular, it is possible to suck too hard and hence the suction system consumes more energy than it saves. Hence if we wish to achieve a specified transition position (dictated by the aerodynamics of the implementation) we must seek the suction distribution which achieves the desired result for the minimum energy cost. Also it is highly desirable not just to show an energy profit but to maximize it. Given these requirements, the route to design is obviously via an appropriately formulated nonlinear constrained optimization problem and in the work to-date we have used a number of methods of solving such problems, namely gradient descent based algorithms, genetic algorithms, simulated annealing. In this presentation, we will cover the following aspects; background and problem formulation; solution algorithms and relative performance comparisons; experimental facilities and comparisons of predicted and measured performance; and on-going research.