Accuracy of Aerodynamically and Structurally Non-Linear Unsteady Vortex Lattice Method for Aeroelastic Prediction in Low-Reynolds Flows

Panel-based aeroelasticity models are commonly used to conduct mid-fidelity aeroelastic analysis. The unsteady vortex lattice method (UVLM) in particular is used when non-linear aerodynamic corrections are needed, for example by utilizing the α-convergence method. While this method is well tested for non-linear corrections in high-Reynolds transonic flows for both steady and unsteady cases, its effectiveness has not been well researched in unsteady low-Reynolds flows. This paper tests the effectiveness of the α-convergence method in this regime by comparing modeling results with original wind tunnel test results. In the steady aeroelastic displacement tests, the aerodynamic non-linearity improved the modeling results significantly, with an error under ±10% at all tested angles of attack, compared to a maximum error of −30.8% for the aerodynamically linear models. In the flutter test case, the aerodynamic non-linearity had less of an impact, with structural non-linearity being more important in this case. However, the maximum flutter speed error for the aerodynamically non-linear model was still lower, at −14.4%, compared to +19.6% for the aerodynamically linear model.