A computational model of three-dimensional, time-dependent flame spread in microgravity environment is presented. The solid is assumed to be a thermally-thin, pyrolysing cellulosic sheet. The gas phase model includes ...A computational model of three-dimensional, time-dependent flame spread in microgravity environment is presented. The solid is assumed to be a thermally-thin, pyrolysing cellulosic sheet. The gas phase model includes the full Navier-Stokes equations with density and pressure variations and six-flus model of radiation heat transfer. The solid phase model consists of continuity and energy eqllations whose solution provides boundary conditions for the gas phase equations. In the numerical procedure, the gas-and solid-phase equations are solved sepaxately and iteratively at each time step. Predictions have been made of flame spread in slow forced flow under gravitational acceleration normal to fuel surface and flame spread in a quiescent environment in an enclosed chamber under gravitational acceleration parallel to fuel surface. Numerical simulations show that, under microgravity, slow-flow conditions, flame spread process is highly unsteady with the upstream flame spreads faster than the downstream flame after a period of ignition. It has also been shown that the level of microgravity has a significant effect on the name spread process.展开更多
文摘A computational model of three-dimensional, time-dependent flame spread in microgravity environment is presented. The solid is assumed to be a thermally-thin, pyrolysing cellulosic sheet. The gas phase model includes the full Navier-Stokes equations with density and pressure variations and six-flus model of radiation heat transfer. The solid phase model consists of continuity and energy eqllations whose solution provides boundary conditions for the gas phase equations. In the numerical procedure, the gas-and solid-phase equations are solved sepaxately and iteratively at each time step. Predictions have been made of flame spread in slow forced flow under gravitational acceleration normal to fuel surface and flame spread in a quiescent environment in an enclosed chamber under gravitational acceleration parallel to fuel surface. Numerical simulations show that, under microgravity, slow-flow conditions, flame spread process is highly unsteady with the upstream flame spreads faster than the downstream flame after a period of ignition. It has also been shown that the level of microgravity has a significant effect on the name spread process.
