Premixed Strained Flame

This example shows how to simulate a steady premixed strained flame. This is essentially the “default” flame configuration for Ember, and most other flame configurations are described by how they differ from this one.

example_single.py:

#!/usr/bin/python
"""
Similar to as is done experimentally (https://doi.org/10.1016/j.combustflame.2009.06.011),
a single disc flame opposing a cold inert is established at a given strain rate. Infinite
burner separation distance assumed. The converged axial velocity profile is plotted.
"""

from ember import *
import matplotlib as mpl
mpl.use('Agg')
import matplotlib.pyplot as plt

output = 'run/ex_single'
a = 300.0

conf = Config(
    Paths(outputDir=output),
    # Chemistry(mechanismFile='gri30.yaml'),
    General(twinFlame=False,
            flameGeometry= 'disc',
            nThreads=4),
    InitialCondition(fuel='CH4:1.0',
                     oxidizer = 'N2:3.76, O2:1.0',
                     equivalenceRatio=1.0,
                     counterflow = 'N2:1.0',
                     Tcounterflow = 300.0,
                     xLeft=-0.01,
                     xRight=0.01,
                     centerWidth=0.005,
                     slopeWidth=0.001,
                     ),
    StrainParameters(initial=a,
                     final=a),
)

if __name__ == '__main__':
    conf.run()

    struct = utils.load(output + '/profNow.h5')

    plt.figure()
    plt.plot(struct.x, struct.V / struct.rho)
    plt.xlabel('Position [m]')
    plt.ylabel('Axial Velocity [m/s]')
    plt.savefig(output+'/FinalAxialVelocity.png')
    plt.close()

The given configuration parameters override default values. The full set of configuration parameters is described in Configuration Options.

• Paths

  • outputDir is the directory where periodic periodic output profiles (prof000000.h5, prof0000001.h5, etc.) and time series output files (out.h5) will be saved. If a relative path is given (as in this example), the path is relative to the directory from which the script is run.

• InitialCondition In this example, the molar fuel composition is specified using the string format supported by Cantera. Alternatively, a vector of mole fractions can be supplied. Here, the oxidizer composition is left with at the default value, which corresponds to air, i.e. "N2:3.76, O2:1.0".

• StrainParameters specifies how the strain rate imposed on the flame varies as a function of time. In this case we specify a constant strain rate.

• TerminationCondition specifies the conditions under which the time integration will be terminated. Here, we specify integration until a specific time. Another option is to integrate until a steady-state solution is reached.

To try this example, run the following command:

$ python -m ember.examples.example_premixed

Or copy the example_premixed.py file to another directory, make any modifications you desire, then run:

$ python example_premixed.py