Winglet design and analysis for low altitude solar powered UAV

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2016
Gölcük, Ali İhsan
To improve the aerodynamic performance of aircraft, comprehensive studies have been carried out in different areas such as wing optimization, tail types and fuselage shape, etc… One of the most important factors affecting the aerodynamic performance of the aircraft is lift induced drag caused by wingtip vortices. Winglet is a device referred as a small, vertical and angled extension attached at aircraft wingtip. It is used to minimize strength of vortices and reduce the lift induced drag. Various types of winglets have been designed and investigated to enhance aerodynamic performances of aircraft. This thesis describes winglet design and analysis performed on rectangular wing of MH 114 airfoil for TÜBİTAK Unmanned Air Vehicle (UAV). The aim of this study is designing elliptical winglet and performing Computational Fluid Dynamics (CFD) analysis for different winglet parameters. The main objective of this study is to compare aerodynamic characteristics of base wing and wing with winglet and investigate the performance of winglets shape in terms of different parameters such as cant angle, sweep angle, taper ratio, toe angle and twist angle. vi Winglet drawing is done in CATIA. In design algorithm, firstly, cant angle, sweep angle and taper ratio parameters are used in a triple combination with each other (27 models). Secondly, toe (6 models) and twist (6 models) parameters are applied to winglet separately which has the best L/D values in the first 27 models. Totally 39 different winglet models are investigated. The computational simulation was performed at low subsonic flow speed in ANSYS using finite volume approach. k-ω SST is used as a turbulence model. To compute the flow around the model, 3-D unstructured tetrahedral mesh is used. The aerodynamic characteristics of lift coefficient (CL), drag coefficient (CD) and lift to drag ratio (L/D) were compared for 39 different winglet models at cruise conditions and zero angle of attack (AOA). To investigate stall characteristic of clean wing and winglet (has best L/D ratio), they were compared at different AOA (-5° to 20°). Moreover, viscous and pressure effects of drag and lift force of clean and the best case configurations are compared and examined. A further point, at different velocities, clean wing and wing with winglet were analyzed in order to observe L/D change. Analysis showed that, elliptical winglet increased L/D value on the order of 8.32% compared to base wing. Hence, a significant improvement in aerodynamic performance is obtained for TİHAS.

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Citation Formats
A. İ. Gölcük, “Winglet design and analysis for low altitude solar powered UAV,” M.S. - Master of Science, Middle East Technical University, 2016.