Drag minimization using active and passive flow control techniques

The objective of this paper is to appraise the practicability of weakening the shock wave and hereby reducing the wave drag in transonic flight regime using flow control devices such as two-dimensional contour bump, individual jet actuator, and also the hybrid control which includes both control devices together, and thereby to gain the desired improvements in aerodynamic performance of air-vehicle. To validate the numerical study, a natural laminar flow airfoil, Rae5243, is chosen and then comparisons with experimental data have been made before the optimization of flow control parameters. After validation study, an efficient gradient-based optimization technique is used to optimize 2D bump parameters including the length, the maximum height, the bump position via shock location, and the crest position via bump and also the jet actuation parameters such as mass flow coefficient, suction/blowing angle, actuation location over the upper surface of the airfoil. The process generally consists of using the simulation code to obtain a flow solution for given parameters and then search the optimum parameters to reduce the total drag of the airfoil via the optimizer. Most importantly, it is shown that, the optimization yields 3.94% decrease in the total drag and 5.03% increase in lift, varying the design parameters of active and passive control devices.