Fire Safety Science Digital Archive

Improvement in the understanding of the structure of flames in micro-gravity is a critical issue for spacecraft fire safety. A numerical study of the influence of a gas diffusion flame on a flow of air over a flat plate in micro-gravity environment is presented in this paper. 3D DNS simulations with a mixture fraction model for combustion have been performed with an adaptation of the Fire Dynamics Simulator code (FDS) developed at NIST. A particular flow speed representative of ventilation in spacecrafts and a fuel injection speed comparable to those induced by pyrolysis is used to illustrate the effect of the sample geometry, the fuel injection and thermal expansion of the flow characteristics. This work is benchmarked with experiments conducted on board of the CNES Airbus-300 and with the numerous observations available in the literature. It was observed that a leading edge can cause velocity overshoots and that fuel injection can have a significant effect in propagating the pressure perturbations downstream. Nevertheless, the calculations show that thermal expansion affects the flow in a much more dramatic way, thus becomes the most important parameter to be considered when evaluating the precision of analytical models.