The effects of tubercles on swept wing performance at low angles of attack

Abstract

Protuberances on the leading edge of wings, also known as tubercles, offer several benefits during stall. However, little is known about their effects on swept wing performance at low angles of attack. In addition, the exact mechanism that is responsible for these currently known benefits has not been experimentally determined. One possible application that could greatly benefit from such a flow control device, but is hindered by these unknowns, is the modern passenger aircraft. As such, this study investigates the effects of tubercles on wings that are similarly swept and tapered to modern passenger aircraft wings, and at low angles of attack. It was found, through flow visualization that tubercles act like vortex generators. Force measurements obtained at a Reynolds number of 220,000, show that for angles of attack ranging from 1° to 8°, tubercles reduce lift and drag by 4-6% and by 7-9.5%, respectively, resulting in a 2-6% increase in the lift-to-drag ratio, and a 3% increase in the maximum lift-to-drag ratio.