Unsteady aerodynamics of adaptive elasto-flexible membrane wing

点击翻译按钮获取中文摘要

Revolutionary concepts for unmanned aerial vehicles are aimed at mission scenarios that include both proportions of efficient loiter and endurance flight and high maneuverability flight. Such scenarios require aircraft which can optimally adapt their aerodynamic properties to the respective application conditions. This project is therefore concerned with new, technically feasible solutions for such versatile aircraft, based on an adaptive flying wing configuration with an adjustable aero-elastic flexible wing. Membrane wing configurations provide the possibilities to continuously alter one or more geometric parameters such as sweep, planform or airfoil and offers performance improvement potential for complex mission profiles. However, the inherent flexibility associated with the membrane creates strong coupling between unsteady aerodynamic loads and the airframe structural response giving rise to highly coupled, multidisciplinary physics. This nonlinear Fluid-Structure-Interaction causes aeroelastic instabilities which can be investigated using sophisticated experimental tools with good accuracy. This proposed research effort is aimed at such investigations which would analyze the effects of design variables involved and consequently would result in determination of aerodynamic and structural properties and configurations to achieve optimal flight conditions by various morphing states. The considered wind tunnel model consists of a beam structure with joints for varying aspect ratio, sweep and local incidence and a flexible lifting surface. Due to the anisotropic membrane design, the deformation of the wing under aerodynamic loads leads to passive flow control with respect to the airfoil shape. Up to now, a first understanding of these mechanisms and the related aerodynamic properties was gained by means of previous wind tunnel experiments and complementary numerical simulations. The current project is now aimed to link the aerodynamic characteristics to specific aerodynamic design variables and to exploit the concept with respect to overall unsteady aerodynamic problems resulting from stall behavior and gust impact. The basic concept of the massive form adaption as well as the use of a flexible lifting surface and its technical implementation combines fundamentally new approaches in the sense of aircraft aerodynamics.