Ground-effect aerodynamics and wingtip vortex and their control

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The long-term objective is the incorporation of ground-effect aerodynamics into aircraft, including rotorcraft, MAVs (micro aerial vehicles) and eVTOLs (electric vertical takeoff and landing vehicles), flying close to the ground to optimize their aerodynamic performance. The optimized aerodynamic performance will lead to a better fuel efficiency and a quieter and safer flight with a reduced environmental signature and impact. The ground effect research is thus of both fundamental and practical significance. The enhanced ground effect-produced lift increase and drag decrease will also advance the aerodynamic efficiency of environmentally friendly winged ground-effect vehicles; a potential cargo and passenger transportation for Canada's vast lakes and iced lands. Over the next 5 years, this research program will investigate the aerodynamic properties and flow physics of both static and oscillating wings and its control in the presence of the ground. Oscillating airfoils and wings in ground effect are two interesting and well-known research subjects. Despite the numerous research work on both subjects, much effort is still needed to investigate these two subjects together. To bridge this gap, extensive measurements of the ground-effect aerodynamics, including wingtip vortex, and flowfield of both static and oscillating wings will be acquired in McGill's wind tunnels by using a combination of various conventional and laser/optics flow diagnostic techniques, including the unique boundary-layer transition and separation detection through the unique multi-element hot-film sensor (MHFS) arrays (designed and fabricated at McGill University). These measurements will also serve as guidelines for lift and drag control in ground effect. To practicalize the ground-effect research, both uniform and non-uniform ground surfaces are investigated. The research program involves several steps: (1) Measurement and characterization of ground effect-produced lift increase and wingtip vortex lift-induced drag reduction of static and oscillating wings and airfoils. (2) Identification of boundary-layer transition and separation and dynamic-stall flow events in ground effect both non-intrusively and in real-time via the use of MFHS arrays. These measurements will then serve as experimental guidelines for lift and drag control of unsteady wings in ground effect. (3) Investigation of non-uniform ground effect, including surface roughness, on aerodynamics and wingtip vortex and their control. It is essential for engineers and researchers to do their part in this type of research for the sake of producing more aerodynamically efficient vehicles operating in ground effect and ultimately reducing their impact on the environment. The benefits of this research will provide HQP (3 PhDs, 4 Masters, and 5 undergraduate interns) that are directly aimed at advancing the nation's aerospace industry and the sustainment of our environment.