Multi-inlet kerosene/air flame with a reduced scheme derived from Luche

Objectives

The Stochastic_ReducedLuche test case shows the reduction of a reduced version of the Luche scheme , for a 0D 2-inlet configuration. Started with 43 species and 302 reactions, we reduce to 23 species and 221 reactions.

Principle

The configuration has 2 inlets, one of air and the second one of pure n-decane. The Luche scheme represents the fuel with a composition mainly based on n-decane (~77%) and we choose to start from a 100% n-decane fuel here, in order to run a relatively quick test case. The target species here are $CO$, $CO_{2}$ and $O_{2}$.

Key parameters

The main parameters are found in the condition.cpp file.

  configuration = "MultipleInlet";
  step = "DRGEP_species";

When you perform the next steps, the given mech is the one chosen from the previously step.

  mech= "mechanisms/luche_red_43s.xml";
  mech_desc = "luche";

  //Inlet 1
  listInlets.push_back(new MultipleInlet(
               /*Temperature*/ 750,
               /*Pressure*/ 1E+05,
               /*Mass flow rate*/ 0.500,
               /*Xk*/ "O2:0.2321, N2:0.7679",
               /*Yk*/ "",
               /**/ false,
               /**/ 0.0,
               /**/ 0.0,
               /**/ 0.0,
               /**/ 0.0));

  //Inlet 2
  listInlets.push_back(new MultipleInlet(
               /*Temperature*/ 750,
               /*Pressure*/ 1E+05,
               /*Mass flow rate*/ 0.017,
               /*Xk*/ "NC10H22:1.0",
               /*Yk*/ "",
               /**/ true,
               /**/ 1.28E-05,
               /**/ 4.91E-4,
               /**/ 810,
               /**/ 251000));

A third inlet is set for the burned gases, with the composition calculated at equilibrium.

   //BurnedGases
  listInlets.push_back(new Characteristics_MultipleInlet(
               /*Temperature*/ 2000,
               /*Pressure*/ 1E+05,
               /*Mass flow rate*/ 0.200,
               /*Xk*/ "N2:0.76308, O2:0.093573, H2O:0.072355, CO2:0.070468",
               /*Yk*/ "",
               /**/ false,
               /**/ 0.0,
               /**/ 0.0,
               /**/ 0.0,
               /**/ 0.0,
               /*tau_t*/ 2e-04,
               /*delta_t*/ 1e-05,
               /*nbIterations*/ 200,
               /*BurnedGases*/ true));

Be careful, the new_mixing parameter must be set to true only for the first step (DRGEP_species in that case).

  new_mixing = true;

Results

DRGEP step

The DRGEP_Species step ranks the species as follows

0  NC4H3
1.12055e-05  C3H2
1.57332e-05  C3H3
0.00137745  C2H
0.00594322  C2H2OH
0.00886416  AC3H5
0.0125369  C2H2
0.0137016  CH2OH
0.0255753  PC4H9
0.0262539  CC10H21
0.0264408  DC10H21
0.0306194  HCCO
0.0318286  CH2HCO
0.0352984  CH2CO
0.0563039  C2H3
0.0568945  C2H6
0.0712826  H2
0.0905014  CH4
0.091268  EC10H21
0.0939194  AC10H21
0.0998347  AC5H11
0.108332  CH2O
0.133531  HCO
0.163655  CH3O
0.19981  AC8H17
0.207181  C2H5
0.241639  AC7H15
0.307516  CH3
0.30758  C2H4
0.416049  O
0.460056  OH
0.874397  H
0.911652  AC6H13
0.91635  BC6H13
0.999616  NC3H7
0.999616  C3H6
0.999907  HO2
1  O2
1  CO
1  CO2
1  NC10H22
1  H2O
1  N2

If we keep 23 species, the trajectories of the targeted species have the same shape as the reference ones but are offset, whereas with 22 species we don't have the good tendencies at all. See for example the CO trajectory with 22 and 23 species :

After choosing the 23 species 93 reactions scheme, we now rank the contribution of all reactions on the targeted species with the DRGEP_reactions step

step = "DRGEP_reactions";

mech = "mechanisms/drgepSpecies23.xml";

new_mixing = false;