Boundary Layer Separation Control on a Salient Back-facing Ramp

Abstract

The research assesses the feasibility and the performance of the serration flow control devices on a salient edge where the laminar boundary layer separation is two-dimensional. Three geometries of serrations: a sharp delta, a double delta and a divergent delta are examined on 15° and 30° deflected, backward-facing ramps. Parameterizing the device spacing and the device-height-to-chord ratio assesses the performance change with different configurations. In addition to the serration geometries, two other improvements, partitioning plates and tip treatments, are investigated. The experiments are conducted in an open-loop wind tunnel with a Reynolds number of 68,000 based on the chord of the flat plate upstream of the ramp edge. In addition to the experimental data, fluorescent oil flow visualization is used to understand the fundamentals of flow physics. This research aims to provide a structurally simpler high-lift-system solution based on the serration devices for general aviation aircraft and UAVs.