A study on wake vortex alleviation of a wing with a reverse delta type add-on device using particle image velocimetry (PIV)

Abstract

The hazardous consequences of a following aircraft encountering the wake turbulence of a large lead aircraft has been well documented and current practice of mandatory separation is less than ideal. The motivation of this project is to develop improved passive add-on devices that are both practical and efficient in alleviating this problem. Particle Image Velocimetry was used in a closed loop low speed wind tunnel to investigate the vortex structures of a half-span wing model with a slender reverse delta type add-on device in the landing configuration. The experimental setup is repeated for various angles of attack and roll angles, and different dimensions of the reverse delta type add-on device. This work investigates the characteristics of the resultant vortices produced by the reverse delta type add-on device, and the wingtip/flap-tip of the half-span wing model by analyzing the flow field in downstream planes perpendicular to the free stream direction. The vortex characteristics dependence on angle of attack and roll, at mean chord based Reynolds number is also analyzed. The peak tangential velocity, peak vorticity and the circulation magnitude of the resultant vortices produced downstream of the half-span wing model are explored. The results are analyzed thoroughly in order to determine if there is any significant decay in the resultant vortex structures. It was found that the reverse delta type add-on device reduces significantly the tangential velocity, vorticity and circulation magnitude by up to 82.9%, 92.6% and 42.8%, respectively and increases the resultant vortex core radius by a factor of 6.57. As it is desirable that add-on devices have a minimal impact on the overall wing, a six component force balance was used to obtain the aerodynamic performance of the half-span wing model. It was found that the reverse delta type add-on device causes a maximum lift reduction of 4.9% and a maximum drag increment of 15.2%.