Combustion simulation on combustor Model
Aim:
To Perform a combustion simulation on the combustor model.
Objective:
plot the variation of the mass fraction of the different species’ in the simulation using line probes at different locations of the combustor .
To plot for CO2, H2O, CH4, N2, O2, NOx emissions & Soot formation.
add the water content in the fuel from 5% to 30% by mole and observe the effect of it on the results.
Given Geomentry(3D model):
Converted 2D geomentry:
By using Split command to its particular plane.
Meshing:
Meshing methods: All Triangles method
Capture promximity enabled
element size: 1 mm
Setup:
General:
Energy enabled
Viscous model:
Species model:
Nox model:
Soot model:
Boundaries:
Air inlet velocity: 0.5 m/s
Air inlet temperature: 300 k
Species mass fraction at air inlet: O2= 0.23
Fuel inlet velocity: 80 m/s
Fuel inlet temperature : 300 k
Species mass fraction at Fuel inlet: CH4 = 1
Initialization method : hybrid
Number of iterations = 1000
Part: 1:
plot the variation of the mass fraction of the different species’ in the simulation using line probes at different locations of the combustor
Residual:
Temperature contour:
Countour Plots for CO2, H2O, CH4, N2, O2, NOx emissions & Soot formation:
Temperature contour Animation of combustor:
using line probes at different locations of the combustor:
Variation of CO2 mass fraction in all line probes:
Variation of H2O mass fraction in all line probes:
Variation of CH4 mass fraction in all line probes:
Variation of N2 mass fraction in all line probes:
Variation of O2 mass fraction in all line probes:
Variation of NOx mass fraction in all line probes:
Variation of Soot mass fraction in all line probes:
Conclusion:
The temperature contours display a flame envelope, within which the temperature initially attains a maximum value following which it achieves a steady state.
The mass fraction of methane decreses to zero as it gets completely consumed to generate heat and by products.
The mass fraction of oxygen is very low in region of combustion that is , the initial lower region of the domain as it gets consumed to generate heat .
The mass fraction of CO2 and water is high in regions of high temperatures as it generate along the heat.
Part-2:
To study the effect of adding water with fuel a parametric study is conducted, The mole fraction of CH4 and mole fraction of water at fuel inlet are the input parameters.
Here Parameter 1 is Mole fraction of CH4
Parameter 2 is mole fraction of water
case: 1 : DP 1 :
Contour plots:
NOx:
Soot:
Variation of Soot mass fraction in all line probes:
Variation of nox mass fraction in all line probes:
case: 2 : DP 2 :
Contour plots:
NOx:
Soot:
Variation of nox mass fraction in all line probes:
Variation of soot mass fraction in all line probes:
Case :3 : Dp 3:
Contour plots:
Nox:
Soot:
Variation of Nox mass fraction in all line probes:
Variation of soot mass fraction in all line probes:
case: 4 : DP 4 :
Contour plots:
NOx:
Soot:
Variation of Nox mass fraction in all line probes:
Variation of soot mass fraction in all line probes:
case: 5 : DP 5 :
Contour plots:
NOx:
Soot:
Variation of Nox mass fraction in all line probes:
Variation of Soot mass fraction in all line probes:
Conclusion:
Supplying Water with fuels to minimize Temperature peaks during the combustion.
Hence the NOx concentrated in the exhaust gas, can be done by means of supplying water into the cylinders , so called wet technologies.
The emulsion supplied in to the cylinder causes the increase of self-ignition delay which affects the flammable mixture becoming more homogeneous in the whole volume of the combustion chamber.
The increased self ignition delay extends the time necessary to spread the injected fuel which results in fewer zones with not enough oxygen. that decreases the intensity of soot and co formation.
Emulsifying the mixture reduces local zones with temperature peaks which leads to decreasing nitrogen activity and NOx concentration.