BiGlobal Stability of Shear Flows: Spanwise & Streamwise Analyses

Laminar-turbulent transition dictates an increase in skin friction. The resulting turbulent skin friction contributes to approximately 40% of the total drag of commercial aircraft. Reducing the turbulent flow region by postponing transition can therefore significantly reduce the carbon footprint and costs of flying. Transition prediction is...

Plasma synthetic jet actuators for active flow control

In the last few decades, active flow control (AFC) technology has been developed to minimize the aerodynamic drag of transportation vehicles and maximize the propulsion efficiency of thermodynamic engines. The key of this technology is the actuators. Among all the actuators that have been proposed (i.e. fluidic, moving object, or plasma-based),...

Finite-dimensional approximation and control of shear flows

Dynamical systems theory can significantly contribute to the understanding and control of fluid flows. Fluid dynamical systems are governed by the Navier-Stokes equations, which are continuous in both time and space, resulting in a state space of infinite dimension. To incorporate tools from systems theory it has become common practise to...

Cross-Flow Instability: Flow diagnostics and control of swept wing boundary layers

The research presented in this booklet focusses on the cross-flow instability. Applying traditional and advanced flow diagnostics, the boundary layer evolution is studied in detail. The topology and evolution of both primary and secondary instability mechanisms is revealed with unprecedented detail for experimental research paving the way for...

Boundary Layer Separation: Diagnostics and Control

The research presented in this thesis focuses on boundary layer separation and, more specifically, on the related physical mechanisms, such as laminar to turbulent transition, with a vision towards effective separation control. The work is divided in three parts, each corresponding to a different separation scenario. The supporting data is...

Active Stall Control of Horizontal Axis Wind Turbines: A dedicated study with emphasis on DBD plasma actuators

The contribution of sustainable Wind Energy (WE) to the global energy scenario has been steadily increasing over the past decades. In the process, Horizontal Axis Wind Turbines (HAWT) became the most widespread and largest WE harvesting machines. Nevertheless, significant challenges still lie ahead of further expansion of HAWT, namely concerning...