This paper shows the present status of the work that has been done at ONERA on numerical optimisation techniques applied to the design of some wing tip devices for lift-induced drag reduction. A wing tip design code has been built by coupling a gradient-based minimisation code with a geometry generator, a grid generator and an aerodynamic code solving the Euler equations. A first geometry generator has been developed for a blended winglet. The straight original wing tip is parameterised so as it can be distorted through continuous deformations depending on the set of design variables to become a blended winglet. A second geometry generator has been developed for a spiroid wing tip following the concept that has been tested in flight on the Grumman Gulfstream II executive aircraft. The design variables define the spiroid loop shape and its twist law. Both wing tip concepts have been applied to an Ultra High Capacity Aircraft (UHCA) generic wing. Full optimisation of a blended winglet leads to substantial drag reduction. But due to the time required to build a complex structured grid generator for a blended spiroid wing tip, only a first attempt of optimising the twist law of a prescribed spiroid tip shape has been made until now. Although the analysis of the global performance of this spiroid tip is somewhat disappointing, it shows promising features for lift-induced drag reduction and a full optimisation including more design variables still should be done.
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