GALCIT Colloquium

A computational parameter study of the viscous axisymmetric supersonic flow over a double cone is made with a view to determining the boundary of the region in which such flows are unsteady. The study is restricted to the case when the boundary layer is laminar. The features of both the steady and unsteady flows in different characteristic regions of the parameter space are described. In particular, the phenomenon of pulsating flow typical of spiked blunt bodies (small first cone angle, θ₁, and large second cone angle, θ₂), appears to be inviscid in nature. In θ₁ − θ₂ space the region of unsteady flow is enclosed in a loop with a lower θ₂ branch and an upper θ₂ branch and a maximum θ₁ between. The location of the lower θ₂ branch is determined by the second-cone detachment angle θ_2d . For this reason, the gas model in one of the conditions is chosen to be thermally perfect carbon dioxide (at Mach number 8) for which θ_2d is quite large. In the other cases the gas model is perfect-gas nitrogen at Mach numbers 2, 4 and 7.7.

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