Publication de 6 numéros par an
ISSN Imprimer: 2150-766X
ISSN En ligne: 2150-7678
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A Solid-Phase Model for Plasma Ignition of Solid Propellant
RÉSUMÉ
In this study we present a one-dimensional model that describes the ignition of solid propellant by a hot gas resulting from the mixing of a plasma jet with the air initially present in the combustion chamber. This model provides information about the ignition process, such as the ignition delay and the effect the physical properties of the ignition stimulus have on it.
Our model is based on a solid phase (thermal) model for ignition. The solid phase theory of propellant ignition is mostly successful in situations where the propellant is exposed to a strong flux of energy, and the velocity of the heating stimulus is high. Plasma ignition is such a situation.
The main conclusions that emerge from our study are the following: (i) Propellant ignition begins when the plasma energy and mass (partial density) in the combustion chamber reache values that change only slightly with the level of input power density, (ii) The ignition time delay is mostly sensitive to the value of the plasma temperature at the capillary exit, and to a smaller extent to its exit velocity, (iii) For low velocities of the ignition stimulus, the radiative flux of energy is always the main factor leading to ignition. However, during the early moments of propellant heating, the convective energy flux is larger than the radiative one. The convective energy flux plays the role of a "pre-heating" factor. At higher velocities and for small values of the density of input energy, the convective energy flux can overcome the radiative one. (iv) The penetration depth of the heat wave into the propellant is very small up to ignition onset. It is larger for longer ignition time delays obtained with lower input powers, (v) Semi-quantitative agreement with experimental measurements was found.
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Zoler D., Appelbaum G., Shafir N., Roshu S., Goldenberg C., Wald S., Shapira M., A new in situ method for the measurement of ignition delays and the propagation of the ignition wave in gun charges, IEEE Transactions on Magnetics, 39, 1, 2003. Crossref