Numerical Investigation of an Unmanned Aircraft Vehicle (UAV) Using Fluid-Structure Interaction

Abstract

This study employed Fluid-Structure Interaction (FSI), which is the coupling of Computational Fluid Dynamics (CFD) with Finite Element Analysis (FEA), to investigate the structural consequences of a wind gust on an Unmanned Aircraft Vehicle (UAV). The wind gust is modelled as a sudden increase to 23 ms⁻¹ in airspeed when the UAV is initially cruising at a velocity of 13 ms⁻¹. In the first step, CFD simulations were carried out using ANSYS FLUENT, and validated against XFLR5 (an open-source software based on Massachusetts Institute of Technology (MIT)’s low Reynolds number CFD program, XFOIL). A steep increase in aerodynamic loads is observed as a result of the wind gust. The values jumped to 244 N for lift and 13.2 N for drag compared to 77.2 and 4.34 N during normal cruise flight conditions. In the next stage, the CFD-obtained pressure fields were exported to ANSYS MECHANICAL to run a structural analysis of the wings’ response to the induced aerodynamic load. A slender component connecting the back-wing’s outer shell and spar, experienced the largest maximum stress of 75.0 MPa, which amounts to a threefold increase from 23.8 MPa during normal flight conditions. In the final step, the FEA numerical results are analytically calculated to determine the structural response of the wing-fuselage connectors. The entire investigation concludes that, although larger aerodynamic loads, and consequently larger stresses are generated due to an increase in wind speed (mimicking a sudden wind gust), the UAV’s structural integrity remains intact.