1. Determination of the Flame Speed of Methane
Muzammil Arshad
Mechanical and Aerospace Engineering Department
Florida Institute of Technology
December 10, 2009

2. OBJECTIVES
To calculate the Laminar flame speed of Methane using Correlations and Chemkin. Verification of calculations experimentally by using a flat flame burner.
These are test calculations for my thesis. The calculations and subsequent experiments were done to check the results which should be similar to the flame speeds achieved by Botha & Spalding.
Methane flame speeds at different pressures, Temperatures and Molar Concentrations of Oxygen are done before.
Project Goal: To calculate the methane flame speed by calculating the Mass flow rate of Methane, nitrogen and oxygen and subsequent experimentation on a test setup.
Objectives
1. Calculation of flow rate of methane, nitrogen and oxygen and finding out the
subsequent pressures.
2. Finding out the Flame speed using Correlations and Chemkin
3. Running various eq. ratios to find out the Laminar flame speeds
4. Comparing the results with Botha & Spalding (also discussed in Glassman)
Approach
1. Literature Review
2. Development of a Generic Hydrocarbon Mathematical Model using Excel and Chemkin
3. Development of a Physical setup for experiments
3. Running Experiments
4. Analysis & comparison of results to the previous research
1/1/2019

3. Literature Review Flat Flame Burner: McKenna Burner
Usage: Experiments on Flame stabilization, heat transfer & flame speeds/structures
Flames generally stabilizes close or even attached to surface of flame holder =>
Conduction + Radiation to flame holder (heat)
Burner Head Cooling methods:
Water cooling
Heating of flame holder well above temp: of unburned gas (Q net loss of flame to burner = 0 (Ideally),=>Adiabatic =>SL = Vu), Q measured by thermocouples attached to burner head
Stabilization of flame far from the surface of burner (depends on burner exit speed)
Vb < SL, Tf < Tad
Botha & Spalding determined heat loss of flames by using water cooled burner and measured it by temperature rise of water
Q is inversely proportional to Vu (also in Figure 19, Glassman)
When Vu = SL and Vu exceeds SL => flame does not remain plane but distorts. The value of Vu corresponding to Q = 0, is found by extrapolation.
1/1/2019

4. Physical Model
1/1/2019

5. Mathematical Model in Excel
Shroud Gas
Area of shroud
E-05 m2
Flow rate
E-05
m3/s
Density
kg/m3
Mass flow rate
E-05
kg/sec
Area of shroud (m2)
Flow rate (m3/s)
Density (kg/m3)
Mass flow rate (kg/s)
Flow rate (CFM)
Flow Rate (SCFM)
Volume flow rate (m3/s)
Volume flow rate (cfm)
Volume flow rate (scfm)
Fuel
Nitrogen
Oxygen
Shroud gas (Nitrogen)
Burner
1/1/2019

6. Mathematical Approach
Mass and Mole fractions of Methane, Nitrogen and Oxygen
Flame Speed Calculations using Correlations
Total Mass flow rate at burner outlet
Mass flow rates of Methane, Nitrogen and Oxygen
Orifice selection
Running time of gas cylinders
1/1/2019

7. Experimental Results & Conclusions
Four sets of experiments performed till now:
Set No. 1:
The results were found in close agreement with previous research i.e. 40 cm/sec. (Plotted Unburned velocity Vu and Heat loss Q)
Main Problem: The trend line for the linear fit was found to be 0.2 which is not linear at all.
Reason: Change in temperature too big.
Set No. 2:
The second round of experiments were performed by reducing the delta T to a minimum of 2 K.
The results produced a linear relationship between Vu and Q but the flame speed came out to be 22 cm/sec. Also, the slope of the line became positive which should have been negative according to Botha & Spalding.
Set No. 3 and 4:
Experiments performed with different approach through which we learned more about the process. New idea has emerged which will be applied in new set of experiments.
Note: Chemkin is being used to find the Flame Speed (SL) that is used in the calculations to get accurate mass flow rates and subsequent pressures
4. Literature Review in Progress to find out more details about the procedure.
1/1/2019