Breno Moura Castro, Wellington Luziano Paulo Junior, Douglas Domingues Bueno, Cleber Spode
DOI Number: N/A
Conference number: IFASD-2024-186
Wind tunnel tests were conducted using a flexible, half-wing model with a control surface. The main purpose of these tests was to evaluate a methodology developed to accomplish nonlinear aeroelastic analyses. A flexible connection of the control surface was fitted with a freeplay mechanism to introduce nonlinear effects in the system. An important feature of the experimental setup was that the model was installed in the horizontal position inside the test section. Therefore, the control surface was subjected to preloading due to
the moment around the hinge line generated by its own weight. Limit cycle oscillations (LCO) were observed in the subsonic wind tunnel tests but only when the equilibrium position of the control surface, which depends on the tunnel flow velocity, was within the freeplay deadspace. The treatment of preloading found in the literature (see Laurenson and Trn [1]), however, was not developed for such a condition. The condition in which the preloading formulation was developed in Ref. [1] assumed that the equilibrium occurs only outside the freeplay deadspace. Therefore, a special treatment for a preload equilibrium inside the freeplay deadspace was developed, for frequency-domain aeroelastic analyses, based on the same assumptions of Ref. [1], for the present conditions. The new approach needed a method for determining the equilibrium position of the control surface for a given wind tunnel flow condition (preload parameter). The determination of the control surface equilibrium position demanded specific aerodynamic coefficients along with mass and inertia properties of the aeroelastic system. Aerodynamics were evaluated both by Vortex Lattice and Computational Fluid Dynamics (CFD) methods. The results of such equilibrium position calculations, then the preloading parameter, agreed well with experiments. The predictions of the adapted methodology for the aeroelastic analysis of a nonlinear system
with preload were consistent with the experimental LCO frequencies and amplitudes evaluated in the wind tunnel tests.