Numerical Study of Laminar Flame Propagation in a Closed Tube with a Full Navier-Stokes Approach

This paper describes a numerical study of the dynamics of the propagation of gas flames in enclosures. The proposed model is based on a primitive-variable, pseudocompressible flow approach, with a projection method to derive an elliptic equation for the perturbation pressure. Finite-rate combustion chemistry is taken into account. The numerical solution of the model equations is conducted by means of a method, developed by the authors, based on an explicit formulation for the time-dependent balance equations, and a direct, band matrix LU solver for the pressure elliptic equation. The use of high-order upwind schemes makes it possible to keep numerical diffusion to a minimum. The model was applied to the study of the transient development of a laminar methane-air flame in a closed cylinder. Detailed numerical results are presented and analyzed to investigate aspects of flame-flow interactions. Issues addressed include the role of location and shape of the ignition zone, the influence of the tube aspect ratio on flame propagation, and the effect of wall friction in the onset of a tulip-shaped flame.