A comparative study between winglet and raked wingtip wing configurations

Abstract

The impact on the reduction in reduced drag for a raked wingtip and winglet configuration was investigated at the University of Seville and compared against a clean wing configuration with no wingtip attached. The results were obtained by experiments in the wind tunnel facilities as well as numerically using the software package FLUENT from ANSYS. To find the optimal winglet configuration several iterations with different designs were done while the raked wingtip does depend heavily on boundary conditions so no iterations had to be done. Both preliminary designs were created in the free vortex-lattice code TORNADO for MATLAB. The results were taken for a detailed design in CATIA V5. Those design were the basis for the numerical investigation but served also as the master geometry for the rapid prototyping. The models were directly printed at the University’s 3D-printer which were later used for the wind tunnel experiments. To obtain the induced drag the classical Trefftz-plane analyze has been applied to the FLUENT results while the experimentally data had to be processed in a different way. Two alternative approaches are presented, one of which is too unstable to produce reliable results while the other approach works better given the right boundary conditions. It has been showed that the winglet reduces the induced drag the most while the raked wingtip reduces the induced drag as well but not as effective as the winglet. The raked wingtip might offer a weight reduction at the wing root due to its ability to reduce the bending and twisting moment as well but it was beyond the scope of the present investigation to give proof.