Feedback-Circulating Design Space Exploration by Multi-Sampling Kriging Model: Exploitation for the Lift Rise by an Aircraft Flap with Yaw-Wise Rotation

Abstract

This study has investigated whether adding yaw-wise rotation to an aircraft flap improves lift performance and elucidated its improvement mechanism. The aircraft is optimized for cruising conditions and lacks takeoff and landing performance. Hence, high-lift devices, such as slats and flaps, compensate for the lift performance. Since flaps move along rails, the gap between the wing and the flap is spanwise constant. However, since the flow field is three-dimensional, the gap should also have a spanwise distribution to raise the lift. Thus, this study defined a design problem for lift maximization with the gap and the yaw-wise rotation angle as design variables. This problem adopted a surrogate model because of the small number of objective functions and design variables. A Kriging model modified to add multiple sample points optimized this problem. Furthermore, the study utilized a feedback-circulating exploration to reach the physical essence of the problem. The result eventually revealed that adding a rotation angle ameliorated the lift. The acceleration of the flow velocity through the gap at the appropriate spanwise position causes the separation of the flap’s upper surface to recede, further reducing the pressure on the wing’s upper surface and growing the lift on both the flap and the wing.