Limit cycle oscillation prediction in high-aspect-ratio wing with freeplay in control surface

Abstract

The presence of nonlinearities in aeroelastic systems can change the dynamics of flight. There are several types of nonlinearities, such as geometrically nonlinear behavior and freeplay, and they can lead the system to limit cycle oscillations (LCO). The first type of nonlinearity is usually found in flexible high-aspect-ratio wings (HAR), which achieve large deformations and have the intrinsic geometrically nonlinear behavior. On the other hand, freeplay typically arises from hinge connections, for example, on the control surfaces of wings. Furthermore, it is common for HAR wings to include control surfaces, and therefore, the resulting system can exhibit both types of nonlinearities. Although several works consider them separately, these nonlinearities can act simultaneously on the system to affect the LCOs. In this context, the present research aims to investigate how the control surface freeplay affects the limit cycle oscillations already existent in HAR wings due to the geometrical nonlinearity. The strain-based formulation will be used combined with the unsteady aerodynamics theory. Numerical simulation will be carried out in the time domain and bifurcations diagrams and phase portraits will be prepared by using the aeroelastic responses. A benchmark HAR wing (without freeplay) will be considered to reproduce the LCO, the different amplitude of freeplay will be included to perform the analysis. (AU)