IUTAM Symposium on Combustion in Supersonic Flows pp 237-248 | Cite as
Numerical Simulations of Unstart Phenomenon in Ramac Device
Abstract
The structure of the detonations around the throat of a ram-accelerator device is numerically studied. The mixture studied is stoichiometric hydrogen-air at 0.1 atm. The physical model includes the integration of a detailed set of chemical reaction rates. The numerical model uses a TVD upwind algorithm and a semi-implicit finite difference scheme for the coupling of the flow equations with the chemical reaction rates. The study focuses on flowfields which result in the unstart phenomenon. We do observe the unstart phenomenon in a limited range of incoming Mach numbers. Although the residence time of the reactive gas in the ramac device is not long enough to induce exothermic chemical reactions, we do observe a chemical reaction originating from a vortex downstream from the throat. Snapshots of the computed unstart show the formation of a very strong detonation outrunning the projectile. Analyses show the importance of the flowfield near and behind the shoulder of the projectile (the throat of the RAMAC device). Changes to the projectile geometry modify the conditions to observe the unstart.
Keywords
Induction Time Deflection Angle Inflow Velocity Fluid Element Freestream VelocityPreview
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