Near-Boundary Flow Phenomena in Unmanned Aerial/Underwater Vehicles

The growth of the Unmanned Aerial and Underwater Vehicle (UAUV) industry is outpacing our understanding of how UAUVs behave in near boundary environments. Search and rescue UAUV applications occur in tight, confined spaces filled with complex obstacles and boundaries. Water sampling UAUV applications occur over wide-open water bodies that involve amphibious operations such as breaching the water's surface. Near-boundary flight provides aerodynamic benefits, such as the "ground effect," seen in animals and helicopters. However, near-boundary flight advantages can be hard to harness because boundary effects can also be destabilizing. They perturb lift (near ground-air or water-air boundaries) and introduce a chaotic amphibious transition region (near water-air boundaries). We studied the aerodynamics and performance of rotor blades near solid and liquid surfaces to explore these near-boundary effects. We then conducted a study of how Micro Aerial Vehicles interact in near-boundary situations and how their aerodynamic performance is affected by the ground. Third, we explored various applications that leverage the advantages of near-boundary flight. Lastly, we compared ground effect over water and solid ground surfaces. The flow structures discovered in this work can quantify the benefits of the near-boundary flight UAVs and offer design strategies for UAUVs that can fly more stably in these near boundary scenarios.