Modeling unsteady flame propagation over thermally thick solid fuels in a microgravity environment

A model for the prediction of unsteady, laminar flame propagation over thermally thick solid fuels under microgravity conditions is presented. Finite-rate chemical kinetics are employed in both combustion and pyrolysis reactions, and the flow field is resolved through numerical solution of the differential equations for continuity, momentum, species mass fraction and energy.;External flows, which range from 0-15 cm/s, are applied and are arranged such that the flames move against the freestream. Oxygen concentration, freestream velocity, radiative surface emittance and ambient pressure are varied in order to gain insight into how they affect the predicted flame spread rate. Results show that surface radiation inhibits the flame spread rate, but has little effect on anything else. Ambient pressure, although it strongly increases the flame spread rate for high opposing flow velocities, is of little consequence at near-quiescent conditions. Decreasing the opposing flow level, for the range of velocities considered, always results in a decreased spread rate, but gas radiation must be taken into account at low velocities if extinction is to be avoided. Lowering oxygen concentration is found to decrease both flame temperature and spread rate. (Abstract shortened by UMI.)...