Challenge on Combustion

#1 Different types of Combustion Simulations in Fluent

Mixing

• Non-Premixed: The reaction zone in distinct stream, mixing takes place at the time of combustion.
• Premixed: The Fuel and oxidizer are mixed at molecular level before ignition.
• Partially Mixed : Fuel and oxidiser are partially pre-mixed at non uniform rations before combustion.

Phase

• Fluid Phase (Volumetric Reactions): When combustion takes place ain fluid phase.
• Wall (Surface Reactions): When combustion takes place on wall.
• Particles (Surface Reactions): Combustion taking place on the surface of the particles.
• Porous Regions : Combustion taking place inside the pores.

#2 Combustion Simulation

2D model

Meshing (Element size 0.5mm)

Setup and Boundary conditions

• Turbulence model: k-epsilon, Standard, Standard Wall functions
• Spices Transport, volumetric
• Mixture material- Methane air
• Mass Fraction of NH4 = 1
• Mass Fraction of O2 = 0.23
• Chemical energy interaction= EDDY DISSIPATION MODEL

Temperatur contour

Post Processing

Results:

Mass Fraction of Methane (CH4)

Mass Fraction of CO2

Mass Fraction of H2O

Mass Fraction of N2

Mass Fraction of O2

Here, apart from good looking images and graphs, no results for mass of pollutants i.e. NOx because N2 is an inert gas, the fraction of NOx concentration is very low. However, by turning on NOx equation in setup spices model , the following image and plot can be achieved for NOx mass fraction.

Results and Cunclusions

• The Highest temperature found in this setup was 2026 C.
• The better mesh refinement will give more realistic data and smooth curves in graphs, the setup is bounded only for around 67000 mesh elements which lead to convergence results in only around 80 iterations, however this is a sufficient setup to predict the combustion behaviour.
• The line probes are being placed with the distance of 0.02 m in distance upto 0.14m length which is fair enough for analysis.