(The) accurate fluid-structure coupling techniques for high aspect ratio wings

Abstract

If the aircraft is perfect rigid body, there will be no aeroelastic phenomena. Aeroelastic phenomena in modern high-speed aircraft have profound effects upon the design of structural members and somewhat lesser but nonetheless important effects upon mass distribution, lifting surface planforms, and control system design. Divergence, Control system reversal, Control effectiveness and load distribution are some of the areas in which static aeroelasticity plays an important role. Several phenomena that can be dangerous and limit the performance of aircraft occur because of the interaction of the flow with flexible components. For example, an aircraft with highly swept wings may experience vortex-induced aeroelastic oscillations. Also, undesirable aeroleastic phenomena due to presence and movement of shock waves occur in the transonic region. In this study, a generic airfoil designed by the inverse method was evaluated with several candidate airfoils. Each airfoil was compared with respect to aerodynamic performance to meet the requirement of HALE (high altitude long endurance) aircraft. The next step was to optimize the candidate airfoils using several optimization formulations to down select an best airfoil. For the analysis of low Reynolds number 2D flow, Drela’s streamtube method was used. After comparing the aerodynamic results, the best airfoil was chosen to construct the baseline 3D wing. The Navier-Stokes code was used to evaluate the overall aerodynamic performance of designed wing compared with other wings. The results show that the designed wing has the best performance in comparison with other wings. An accurate method of static fluid-structure coupling for high aspect ratio wings was developed. By extending the traditional Rayleigh-Ritz method which only captures the first-order transverse motion, the second-order accurate quadratic modes method is proposed to predict the correct deflection of high aspect ratio wings. The same methodology is also ...