Aerodynamic drag reduction, from science to control strategies in aerospace and sport

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Aerodynamic drag is a form of loss that manifests through pressure and shear. For aircraft, engines produce thrust to overcome drag. In sport such as cycling, drag limits the speed an athlete can maintain. Reducing drag has a direct path to energy conservation or increasing performance. This is important because the impact of the consumption of non-renewable energy sources on our environment is undeniable. In Olympic and Paralympic Games, as examples, aerodynamic advancements can greatly affect our national presence at the podium. Flow control is a key tool that can reduce drag, and consequently, conserve energy, or maximize performance. The theme of this research program and long-term vision is the development and implementation of novel physics-based flow control technology for applications relevant to Canadian aeronautical and sport-based industries. At the core, this program considers the fluid dynamics and control of boundary layers and flow separation. Expertise in these flows is also complementary because the boundary layer preceding separation influences the wake and pressure drag. This program is underpinned by creating knowledge within the gaps of the fluid dynamic mechanisms leading to drag as a precursor to the control innovations ultimately sought. In sport, the role of unsteady motion on drag is largely unknown. The methodology is to build from the study of flow separation and vortex formation for unsteady motion to launch new directions in drag reduction technology. In the short-term, the focus resides on the uncharted unsteady yaw motions, which parallel aspects of athlete limb motions, and forms the basis to reach the long-term goal of faster athletes. Active flow control systems targeting high shear events occurring in the turbulent boundary layer, or aimed at delay of transition to turbulence, opens new possibilities in the reduction of the environmental footprint of aircraft. The experimental framework of this research also inherently addresses practical challenges associated with use of sensors and actuators that relate to the applications this research supports. The short-term objectives address the boundary layer response to dynamic actuation within a tractable model flow control problem as an integral component of the long-term research vision of reduced aircraft drag. The practical ramifications of this research program are in energy conservation and increased performance. This research supports the Canadian aerospace and sport-based industries, and excellence of Canadian athletes. This research is also envisioned to bring public exposure to the significance of aerodynamic advancements and act as a catalyst to bridge the gap between science, media, and the community. At the core of this program are the HQP (2 PhD, 3 MASc, and 10 Undergraduate) that will advance this program and bring extensive training to support Canadian industry.