Summer Researcher with Dr. Zubaer Hossain
Mechanical Engineering, Mathematics
University of Delaware
I am a Rising Senior at the University of Delaware majoring in Mechanical Engineering and minoring in Mathematics. I am looking forward to graduating in the upcoming year and joining the Aerospace industry to assist in the design of hydrogen-powered aircraft.
Donovan’s Research Summary:
First, the design of individual winglets was completed in SolidWorks. The first winglet was made to be a poorly designed benchmark winglet, with a rectangular cross section and flat front face to increase drag and decrease lift. Three other winglets were designed with identical airfoiled wings to reduce any error associated with wing design as opposed to winglet design.
Simulation of all winglet designs were done in the software Simscale. Boundary conditions in Simscale were initialized by meshing around the winglet and using slip conditions on the surrounding walls, assuring a uniform non-zero velocity around the mesh. The no-slip condition was applied to all surfaces and vertices of the winglet to generate net pressure and viscous forces on the winglet. Note that all forces involved are net forces, so they are applied to the winglet and 200 millimeter wing connection.
This simulation method yields more accurate results than if the winglet was just present without the winged connection. The four
winglets that had simulations performed on them were the NASA Whitcomb Winglet, Dihedral Sailplane Winglet, 90 degree
Raked Winglet, and poorly designed winglet.
In terms of optimizing the drag and lift coefficients the Dihedral Sailplane winglet outshined the others, however, the stress analysis performed in SolidWorks revealed the Dihedral winglet experienced the most Von Mises Stress under load. It was determined this high Von Misses stress could potentially lead to earlier failure than the other winglets due to a lower fatigue limit.
In contrast the winglet with the lowest Von Misses stress was the 90 degree Raked Winglet, which also had the second highest coefficient of lift to drag ratio just behind the Dihedral winglet. The stress gradient revealed that most of the stress is dissipated into the center of the winglet, while most of the stress is directed into the wing. Thus, leading to a conclusion of the raked winglet out performing all designs in terms of rigidity and stress dissipation. But falling slightly short to a winglet solely designed to reduce drag and increase lift. Therefore, the raked winglet is better suited for applications where wing design takes prevalence over winglet design, while the dihedral winglet is better suited for high performance at lower flight
Note, that after stress simulations it was determined a dihedral winglet spanning the entirety of the airfoiled wing would be relatively equal in terms of stress dissipation, making it the ideal design for passenger aircraft.