Design of Leading Edge Vortex Flaps for Delta Wings at Low Speeds

Engineering: 4th Place, Honorable Mention (The Ohio State University Denman Undergraduate Research Forum)Small unmanned aerial vehicles (UAVs) have become increasingly important in the role of tactical reconnaissance. Frontline troops rely on the ability to easily deploy UAVs from any position in order to collect time sensitive intelligence. One of the primary criteria for small UAVs is that of portability. In order to address this need, it has been proposed to design a UAV with a foldable delta wing made of a flexible material. However, delta wings typically suffer from decreased aerodynamic efficiency which is the ratio of the lift created to the drag produced. Poor performance in this regard is especially pronounced at low speeds. Since range is directly proportional to the maximum achievable aerodynamic efficiency, a delta wing equipped UAV would need to expend more propulsive energy to accomplish a given mission in comparison to conventional designs. A potential solution exists in the form of Leading Edge Vortex Flaps (LEVF). Essentially a flap-like control surface attached to the wings leading edge, such devices have been shown to improve aerodynamic efficiency by as much as 20 percent on conventional delta wing aircraft. The objective of this research was to determine an effective flap design with the goal of achieving the same aerodynamic improvements for flexible delta wings at low speeds. A secondary objective relating to the potential use of LEVF devices as a means of vehicle control was also investigated. Using Computational Fluid Dynamic (CFD), two and three dimensional analysis was performed on 30° and 60° delta wings in combination with various LEVF geometries. Effort was given to refining the geometry of a fully three-dimensional flap model as well as to determining the primary flow mechanisms that govern the creation of lift, drag, and ultimately aerodynamic efficiency. The results indicated that, at the low velocities tested, LEVF devices could improve the Aerodynamic Efficiency of a 30° delta wing by 4 percent and a 60° delta wing by as much as 10 percent. While a preliminary investigation into the potential for using LEVF devices as a means of vehicle control produced some encouraging results, additional work would be needed in order to make any definitive conclusions.Academic Major: Aeronautical and Astronautical Engineerin