Dynamic Control of Turbulent Transition in Cross-Flow Dominated Boundary Layers via Gaussian Processes

Surface temperatures on the swept fin were measured with infrared thermography. Heat flux was computed with an implicit two-slab finite volume method, which is shown to be less error-prone than standard approaches. Spectral analyses on the heating data identified critical cross-flow wavelengths.

Based on these results, two actuators were designed. The first actuator, Dynamic Discrete Roughness Elements, modulates the amplitude of surface roughness on the fin. The second actuator, Dynamic Wavelength Plasma Roughness, changes the voltage of a DBD plasma actuator and forces integer multiples of a design wavelength.

Both designs delayed turbulent onset and reduced surface heating. The experiments revealed a strong dependence of the critical wavelength on the fin yaw angle. Closed-loop control was demonstrated, in which a Gaussian Process model-based control system minimized the integrated surface heating utilizing the DWPR actuator and a real-time solution of the heat equation.<p></p>