Global Aero-Structural Design Optimization of Composite Wings with Active Maneuver Load Alleviation

In the scope of the DLR project VicToria~(Virtual Aircraft Technology Integration Platform), an integrated process for aero-structural wing optimization based on high fidelity simulation methods is continuously developed and applied. Based upon a parametric geometry, flight performance under transonic flight conditions and manoeuvre loads are computed by solving the Reynolds-averaged Navier-Stokes equations. Structural mass and elastic characteristics of the wing are determined from structural sizing of the composite wing box for essential manoeuvre load cases using computational structural mechanics. Static aeroelastic effects are considered in all flight conditions and active manoeuvre load alleviation is integrated in the process. Global aero-structural wing optimizations are successfully performed for wings with and without active manoeuvre load alleviation. The active manoeuvre load alleviation is introduced with a simplified modelling of control surface deflections by using a mesh deformation technique. The minimization of the fuel consumption for three typical flight missions represents the objective function. Wing optimizations are performed for variable and constant wing planform parameters as well as for wings with conventional composite wing box structure and for more flexible wings. The latter is accomplished by introducing modifications of the structural concept and the strain allowable. A significant mass reduction of the optimized wing box is obtained for wings with active manoeuvre load alleviation, resulting in a drop in fuel consumption of about 3%. For wing optimizations with the more flexible wing concept the active manoeuvre load alleviation shows an additional reduction of the fuel consumption in the order of 2%. The wings with active manoeuvre load alleviation results in optimized wing geometries with increased aspect ratio and reduced taper ratio.