Influence of Wing Trailing Edge Flap Deflection of a Transport Aircraft Configuration on the Aerodynamic Flight Performance in Off-Design Flight Conditions

Kurzfassung

In the present work, the influence on the aerodynamic flight performance of a transport aircraft configuration under off-design flight conditions is investigated by varying flap deflections at the trailing edge of the wing. For this purpose, the DLR-F25 aircraft configuration. The flap deflections are added to the configuration through mesh deformation. Based on numerical simulations with the DLR TAU code, different flap deflections are analyzed in the design point at flight altitude 35000 ft and in the off-design point at flight altitude 29000 ft. In addition, the Mach number is varied in the off-design point. The optimal flap deflections are determined either on the basis of the results of the simulations from the Design of Experiments (DoE) or by means of surrogate-based optimization (SBO). The glide ratio is used to evaluate the aerodynamic flight performance. For an optimized configuration in the off-design, aerodynamic-structure coupled calculations were carried out to identify the influence of aeroelasticity on the aerodynamics. The results of these investigations have shown that the current wing area is not optimized for the design point. In order to increase the glide ratio and thus improve the aerodynamic performance, the flaps must be deflected variably in the spanwise direction. The aerodynamic flight performance can also be improved in off-design by flap deflections. The glide ratio can be increased by decreasing velocity in the off-design conditions. Taking into account the aeroelastic forces at the off-design point results in deformation of the wing. This in turn leads to an impairment in aerodynamic performance.