Simulation and Control of Three-Dimensional Separated Flows around Low-Aspect-Ratio Wings

Kunihiko (Sam) Taira Postdoctoral Research AssociateDepartment of Mechanical and Aerospace EngineeringPrinceton UniversityPrinceton, NJ Micro air vehicles often fly with flow separation on their low-aspect-ratio wings due to the unique design and operational environment. However, three-dimensional flows around such vehicles have not been well understood compared to the classical high-Reynolds-number flows around conventional aircraft. To offer fundamental understanding of the flow field around small-scaled vehicles, a new formulation of the immersed boundary method is developed and used to perform three-dimensional flow simulations around low-aspect-ratio wings at low Reynolds numbers. The study highlights the unsteady nature of separated flows for various aspect ratios, angles of attack, and planform geometries. Following an impulsive start, the short and long time behavior of the wake and the corresponding forces exerted on the wing are examined. At high angles of attack, the leading-edge vortices are observed to detach in many cases, resulting in reduced lift. Inspired by how insects benefit from the added lift due to the leading-edge vortices, actuation is introduced to increase lift by modifying the three-dimensional dynamics of the wake vortices behind translating wings. Successful control setups that achieve lift enhancement by a factor of two in post-stall flows for low-aspect-ratio wings will be presented.

Location: Seaver Science Library (SSL) 150

Audiences: Everyone Is Invited

Contact: April Mundy