Expt 3: Numerical Characterization of Laminar Premixed Methane-Air Flames

Numerical experimentation:

Use of mathematical model to understand flame characteristics under certain controlled conditions. It mimics a real-life situation.



Necessary tools


    Elements of mathematical model:
  • Equations (also called governing equations) that describe behavior of the system under consideration.

  • Auxiliary equations (also called boundary conditions) that describe how the system can be modified.

  • Methods and algorithms to combine the above two elements in order to obtain numeric data for a given set of conditions.



Definition of the problem


    Importance of laminar premixed flame:
  • Simplest of the flame configurations
  • Essential for understanding of practical combustion systems
  • Model problem for combustion


    Typical configuration:
  • Flame is situated in a flowing mixture of methane fuel and atmospheric air.
  • Far away from the flame to the left, no reaction occurs -> cold boundary.
  • Reactions and heat release occurs in a narrow region.
  • To the right, only products exist at high temperatures.


    Problem Definition
  • Model the behavior of flame in response to changes in equivalence ratio.
  • Describe flame structure; calculate burning velocity at three equivalence ratios.


  • During the combustion process:
    • The components and heat are transported from flame zone to other locations.
    • Mass diffusion and heat conduction occur predominantly near the flame.

  • Governing equations should reflect these physical processes in terms of
    • Physical laws of motion (Newton's laws)
    • Energy (first law of thermodynamics)
    • Mass conservation

  • Our task:
    • Apply these principles to a reacting flow process.
    • Take into account the simplifying assumptions.
    • Build a model of the laminar premixed flame.