THE CEILING EFFECT AND FLIGHT INSIGHT OF UNMANNED AERIAL VEHICLES DURING PROXIMITY INSPECTION OF BRIDGES VIA COMPUTATIONAL FLUID DYNAMICS MODELING AND SIMULATIONS

UAVs face some critical challenges in pervasive applications, such as navigation in GPS-denying areas, obstacle avoidance, and tradeoff between payload and flight time. The INSPIRE UTC at Missouri S&T is developing a clamping UAV, a hybrid flying and traversing robot, to make it possible that the UAV flies under a bridge girder, grabs the girder, and moves along the girder for inspection. This heavy UAV is difficult to control underneath the deck when equipped with multiple cameras. In this study, CFD modeling and simulation are conducted to understand the flight behavior and ceiling effect of the UAV under the bridge deck. First, 3D scanning and reverse engineering are used to build CFD models. Second, a series of single propeller tests are conducted to validate the process of CFD modeling and the simulation results. Third, based on the workflow and technique validated through single propeller CFD analysis, the CFD model of an entire UAV is established and analyzed to predict the behavior of the UAV and understand its interaction with upper boundaries as it approaches the bridge ceiling vertically. The CFD simulation results show that the ceiling effect of the designed clamping UAV is insignificant when the UAV approaches the standard bridge deck with enough depth. These results provide a technical reference for the design and control of the clamping UAV for bridge inspection.