A water tunnel flow visualization study was performed on isolated forebody models of varying nozzle position and nosecone semi-apex angle to investigate a reversal phenomenon observed in forebody vortex manipulation using forward facing nozzles. The effects of blowing at different rates were examined at various angles of attack. Three categories of vortex manipulation were observed and named: low-blowing reversal, where relatively low blowing rates caused attachment of the vortex on the blowing side; switch, where moderate rates of blowing caused detachment of the vortex, and high-blowing reversal where high rates of blowing caused re-attachment. The occurrence of the two reversal categories was found to depend upon a combination of nozzle azimuth and axial location, semi-apex angle, and, to a lesser degree, angle of attack. It is hypothesized that vortex manipulation results from two competing effects of the blowing fluid: entrainment favoring attachment, and displacement favoring detachment. A CFD analyses was attempted to gather additional insight but no valid solution could be produced.*; *This dissertation is multimedia (contains text and other applications not available in printed format).
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