Aeroelastic modeling and analysis of wings in proximity

Abstract

This study investigates the effects of aerodynamic interaction on the aeroelastic characteristics of wings in proximity which is considered to be aerodynamically more efficient than the single wing case. The structural model of the wing is based on the first-order shear deformation theory and analyzed by the finite element method. The flow surrounding the wings is governed by potential theory and the aerodynamic loads are computed using the unsteady vortex lattice method. The aeroelastic simulation framework is established by integrating the structural and aerodynamic models within the flexible multibody dynamic program to solve the aeroelastic equations of motion in the time domain. Cantilever wings in proximity, arranged in biplane configuration, with different geometric parameters such as gap, sweep angle, dihedral angle, and stagger are considered in the analysis. The numerical results show that the smaller gap between the wings magnifies the aerodynamic interaction effect and decreases the onset of flutter speed. Sweeping the wing backward further reduces the flutter boundaries of the biplane model mainly due to changes in the wing's structural modal whereas the effect of dihedral angles is understated. The effect of stagger is more evident for a smaller gap and mostly leads to an increase in the flutter boundary. The aeroelastic responses are independent of initial disturbance and show a natural tendency to oscillate with a phase difference. This investigation warrants the importance of considering biplane wings as a single system for a gap lower than wing chord length as well as the significance of other geometric parameters in the aeroelastic calculation.