Low Fidelity Modelling of the Nonlinear Aerodynamics of Spoilers

Abstract

Spoilers are secondary control surfaces mainly used for roll control, load alleviation and as airbrakes. However, when considering very flexible wings, spoilers could also play a primary role in controlling the aircraft's attitude as an ideal alternative or complement to ailerons since they are distributed over the wingspan and, therefore, potentially less affected by the wing deformation. However, due to its nonlinear nature, spoilers aerodynamics can only be accurately simulated through high-fidelity software, such as CFD. The work presented in this paper aims to provide a novel method to model spoiler aerodynamics in a low-fidelity Unsteady Vortex Lattice framework by proposing an approach able to predict the impact of multiple spoilers on the wing lift distribution. The approach is verified through data acquired in a series of wind tunnel tests on a rigid wing equipped with servo-controlled spoilers carried out in the University of Bristol Low Turbulence Wind Tunnel. Load cell measurements and PIV data are shown for comparison. Numerical predictions show good agreement with the experimental data proving the low-fidelity UVLM aerodynamic solver's ability to successfully model the nonlinear flow field behind the extended spoiler.