1. Aerodynamic Analysis of Airplane Winglet to Maximize Design Efficiency Cooper Gould   Texas Christian University 2901 Stadium Drive TCU Box Fort Worth, TX, 76129, US
Abstract
One debated topic within the aerospace world is what winglet design actually maximizes lift while minimizing drag. The topic has substantial bearing given that improving wing design could save airlines/customers millions of dollars while concurrently reducing jet fuel consumption. At this stage in my honors thesis, I have been striving to replicate a study done by the American Journal of Engineering Research in an effort to validate my methodology, thus substantiating original designs to be tested in the future. I propose to delve further into winglet intricacies, analyzing the aerodynamic impact of varied cant, blend, airfoil shape.
1. Airfoil and Winglet Modeling
All of my airfoil/winglet combinations were modeled on Autodesk Inventor using techniques including splining and lofting. The airfoil used in the AJER study, and thus my experiments, is the NACA 0012 airfoil – a symmetric wing with no camber and 12% maximum thickness. Given a maximum span of 6 inches, I was able to determine the appropriate chord length while maintaining the proper aspect ratio. The winglet’s were designed using the criteria illustrated in Figure 1. Extensive geometry was utilized to maintain uniformity between all design variations as related to the airfoils, winglets, and wind tunnel fasteners.
2. 3D Printing of Designs
Upon completion of CAD designs, the airfoils were sliced into layers and then exported to a Stratasys 3D printer. Given that surface smoothness is essential to accurate modeling, investigation was done into the orientation with which the airfoils were printed. It was found that layering the ABS plastic progressively higher along the cross section of the foil produced the most polished curvature. Furthermore, threads and countersinks were utilized to enhance strength and aerodynamic properties.
3. Wind Tunnel Testing
The TCU wind tunnel was exploited in order to perform an abundance of tests comprised of variable combinations of speed, angle of attack, and winglet blend angle. The procedure included calibrating the drag force due to the attachment post itself, iterative zeroing of the force transducer, and experimental testing taken at random order in an effort to eradicate experimental error. The results are shown below in Figures 3 – 5, highlighting the correlation between my results and those found by AJER. Proper fan speed for my experiments was derived through a Reynold’s Number matching. Both studies highlight the effectiveness of the 30 degree winglet in generating lift while also illuminating the advantage of this design in terms of lift to drag ratio. The drag associated with the airfoil without a winglet appeared to be particularly high, especially with increasing angle of attack. Both studies illustrate stall, a result of flow separation replacing laminar condition, occurring at around a 10 degree angle of attack. Clearly, results align, thus promoting further investigation into the effect of winglets on wing tip vortices and associated induced drag forces.
Fig. 2 Winglet Design
Fig. 1 Winglet Design
Fig. 3 Lift
Fig. 4 Drag
Fig. 5 L/D Ratio
Fig. 6 AJER Lift
Fig. 6 AJER Drag
Fig. 7 AJER L/D Ratio
Proceedings of the 2018 ASEE Gulf-Southwest Section Annual Conference The University of Texas at Austin
April 4-6, 2018