Aeroelasticity Investigation of Generic SUAS-Membrane Wing Validation Study

Abstract

For the purpose of collaboration within AFRL and with outside research organizations on micro-munitions current and future research, a common SUAS configuration, named Generic Micro-Munition (GENMM) was designed and promulgated by AFRL. The GENMM design incorporates a circular fuselage, a thin cambered wing of 24 inches wingspan and a fuselage length of 17 inches, and a conventional tail. The objective of this effort is to study the aeroelastic characteristics of the GENMM at different Reynolds numbers using Direct Numerical Simulation and to investigate techniques to reduce the adverse effects of flow separation and unsteady aerodynamics. For the aeroelastic predictions, the first-principles-based approach is undertaken, where the flow solver is fully coupled with the structural dynamics solver. This approach, employed in the CoBi software, is able to accurately and efficiently predict the unsteady aerodynamics, boundary layer separation, lift and drag, and the stress and structural deformation of the flexible wing of GENMM. The focus of this paper is on the systematic validation of this coupled solver for a specific membrane configuration, where extensive experimental measurements are available. Comparisons between the present simulations and experiments are made for the following quantities: a) mean membrane shape; b) the dominant membrane oscillating frequencies under different angles of attack and freestream velocities; c) flowfield visualizations at low angle of attack; d) instantaneous velocity vector field; e) membrane displacement response to instantaneous flowfield; f) use of rigid and flexible membranes; g) the distribution of the mean velocity field at low and high angles of attack; and h) the distribution of turbulence intensity at low and high angles of attack. Comparisons of these quantities show favorable agreement of the present simulation against measurement and hence build a sound validation study for the coupled fluid-structure solver.