Passive Control of High-Speed Separated Flows Using Splitter Plates

An experimental investigation was conducted to study the effects of passive splitter plates placed in the recirculation region behind a blunt-based axisymmetric body in supersonic flow. The goals of this research were to obtain a better understanding of the physical phenomena that govern these massively separated high-speed flows and to determine the flow-control authority of this passive device. Triangular splitter plates dividing the near wake into 1/2, 1/3, and 1/4 cylindrical regions were designed to exploit specific stability characteristics of this flow, to alter the base pressure, and ultimately to affect base drag. Mean static pressure measurements acquired from the base and splitter plate surfaces were the primary metric to assess the influence of these plates. Schlieren imaging, surface flow visualization, and pressure-sensitive paint measurements were also employed to document the near-wake flowfield, surface flow structure, and surface pressure, respectively. The insertion of these splitter plates only slightly affected the base pressure and near-wake flowfield, which suggests that the recirculation region may not be the most sensitive area to apply this flow control methodology.