Adaptive Surrogate-Based Optimization of Vortex Generators for Tiltrotor Geometry

The design of vortex generators on a tiltrotor-aircraft infinite wing is presented using an adaptive surrogate modeling approach. Particular design issues in tiltrotors produce wings that are thick and highly loaded, and so separation and early-onset buffet can be problematic, and vortex generators are commonly used to alleviate these issues. In this work, the design of vortex generators for the elimination of separation is considered using a viscous flowfield simulation. A large design space of rectangular vane-type vortex generators is sampled and simulated, and a radial-basis-function surrogate model is implemented to model the full design space. An efficient adaptive sampling approach for improved design space sampling has also been developed that balances the properties of space filling, curvature capture, and optimum locating. This approach has been tested on the design of a vortex generator on a highly loaded infinite wing, with a representative tiltrotor airfoil section, using a five-dimensional design space. The design of the vortex generators using this approach shows that elimination of the separation is possible while simultaneously reducing the drag of the wing with optimized vortex generators, compared to the clean wing.