Influence of a "slip" splitter plate on transonic shock oscillation on airfoils

Abstract

The effect of a "slip" splitter plate to control the buffeting phenomena at transonic speed is reported. The aim is to examine the wake vortex of airfoils when there is large flow unsteadiness arising from self-excited shock induced oscillation. While the use of a "slip" splitter plate is a hypothetical one, its use here is as a tool to better understand the flow phenomena involved. The study is made using unsteady computation of Reynolds-Average Navier-Stokes equation with a two-equation k-ω turbulent model with lagged effect. Two different airfoils are investigated; a symmetric non-lifting 18% thick bi-convex airfoil and a lifting BQK No.1 supercritical airfoil. The effect of locating the splitter plate placed downstream from the airfoil trailing edge reveals that the influence from the interaction between the upper and lower surfaces is persistent. Our preliminary study here shows that although the vortex size can be decreased with a splitter plate the communication between the top and bottom surfaces at the trailing edge is still important and present with small separation distances. The size of the required splitter plate is approximately a function of the size of the vortex formed.