Aerodynamic Analysis and Vibration Response of Spherical Shell with Meshed Net for Unmanned Aerial Vehicle Application

Abstract

Shelled unmanned aerial vehicle (UAV) has proven to be efficient and effective in visually inspecting wide varieties of structure types in challenging locations including narrow or complex environments. In bridge inspection, shelled UAVs can encounter another problem considering the outdoor environment such as the presence of wind. Improving the flight performance by reducing the overall drag means decreasing the overall area of shell as well. However, this could danger the UAV because of the larger openings of the shell. Prospect solution is the additional protection of the spherical shell by adding meshed net. In this study, the aerodynamic characteristics of the fullerene type spherical shell with meshed net was investigated at different wind speeds and sideslip angles. Moreover, in the presence of wind, the spherical shell with and without meshed net will experience significant vibrations that will also affect the flight performance of UAV due to the combination of the wind load and its material structure. Thus, the vibration response was also investigated at different wind speeds. For the aerodynamic investigation, computational fluid dynamic (CFD) simulations and wind tunnel experiments were conducted to determine the performance of the shelled UAV with and without meshed net. The contribution of drag force by the spherical shell increased by an average of 3.95. For vibration response, a wind tunnel test was performed. Experimental data at different wind speeds were extracted and analysed via the MATLAB vibration toolbox. Based on the evaluation on the frequency-response, the spherical shell with multifilament fishing line mesh indicated higher amplitude value compared to the spherical shell with monofilament nylon mesh.