High-Lift Airfoil Interacting with a Vortical Disturbance: Wind-Tunnel Measurements

Abstract

This paper describes experimental investigations on the effect of large-scale disturbances interacting with the flow around a two-element airfoil. Quasi two-dimensional transversal vortices are created in a closed wind-tunnel test section shortly after the nozzle. Convecting along the test section, these vortices interact with a two-element airfoil in high-lift configuration. Various measurement techniques are used to identify and characterize these complex interactions. The techniques are phase-locked particle image velocimetry, time-resolving five-hole probe, time-resolving static pressure measurements, and time-averaged measurements of the static pressure distribution of the high-lift airfoil. The vortex generation and evolution along the empty wind-tunnel test section is discussed before considering the vortex–airfoil interactions. As a result, the influence of the induced vortices on the time-resolving static pressure along the airfoil surface and the interaction with the airfoil flap flow is described. The findings are linked to flowfield images and the induced flow effects (the circulatory effect and the local velocity effect) are discussed.