In a perturbation analysis,a two-dimensional theoretical solution based on Navier-Stokes equations is constructed for gaseous slip flows in a micro-channel with different slip conditions.The micro-channel flow is investigated theoretically and numerically at various inlet pressure ratios,aspect ratios and fluid cases with several slip models.The influence of the rarefaction effect,thermal creep effect and slip conditions is emphasized.Simulations show that Kn is a key parameter in determining the magnitude of rarefaction effects while Re is a key parameter indicating the thermal creep.Excellent agreements with experimental results are observed in both theoretical and numerical results of low-velocity micro-channel flows at very large aspect ratios.

CH₄/Air premixed combustion within a two-layer porous medium burner is numerically simulated in a laminar combustion model.Heat exchanges with radiation in the solid and with convection between the gas and the solid are considered.A detailed reaction mechanism GRI 3.0 is used and a dispersion formula is added to the equations.The stabilization of the flame and the emission output are investigated.The results are compared with those of a one-layer burner.It is concluded that a two-layer burner has wider flux range in stabilizing the flame nearby the two-layer porous medium interface.

Gas filtration combustion in porous media differs substantially from the combustion with free flame. A one-dimensional model is proposed, and a perturbation theory is used for the combustion front velocity analysis of the methane-air premixed combustion in an inert packed bed, The temperature distribution is predicted for either fully-developed or transient combustion state, based on direct solution and Green's function method. Finally, computational experiments are given and the results are satisfactory.