ECFM-CLEH Model Reference


Theory	See ECFM-CLEH.
Provided By	[physics continuum] > Models > In-Cylinder Models
Example Node Path	Continua > Physics 1 > Models > ECFM-CLEH
Requires	Space: Three Dimensional Material: Multi-Component Gas Reacting Regime: Reacting StarIce: In-Cylinder StarIce: In-Cylinder Combustion
Properties	Key properties are: Start Time of ECFM, ECFM Fuels. See ECFM-CLEH Properties.
Activates	Physics Models	Ignition Models, Turbulent Viscous Regime, Segregated Flow, Equation of State, Time
	Boundary Inputs	Fuel/Oxidizer Mixing State Specification See Boundary Settings.
	Model Controls (child nodes)	Mixing Diffusion Post-Oxidation EGR Composition
	Other Nodes	[physics continuum] > Table Generators > ECFM-CLEH Equilibrium Table Generator See Table Generators Reference.
	Solvers	ECFM-CLEH Combustion. See ECFM-CLEH Combustion Solver.
	Monitors	Zf Variance
	Field Functions	AImode Combustion Heat Release Rate, Burnt Density, Burnt Temperature, DIFF mode Combustion Heat Release Rate, Diffusion Combustion Progress Variable, Enthalpy of [species], Equivalence Ratio, Exhaust Gas Recirculation Mass Fraction, Exhaust Gas Recirculation Mole Fraction, FPmode Combustion Heat Release Rate, Global Combustion Progress Variable, Input Equilibrium Library Temperature, Mass Fraction of [species], Molar Concentration of [species], Mole Fraction of [species], Molecular Weight of [species], PSTOXmode Combustion Heat Release Rate, SImode Combustion Heat Release Rate, Specific Heat of [species], Total Conditional Fuel Mass Fraction, Unburnt Temperature, YfeqDIFFFuel Equilibrium Mass Fraction Factor, YfeqPMFuel Equilibrium Mass Fraction Factor, YfeqPMLIMFuel Equilibrium Mass Fraction Factor, YfeqPSTOXFuel Equilibrium Mass Fraction Factor, YuC (S), YuH, YuN, YuNO, YuO, YuOH, YuYMWCLEH, Zf Segregation Factor, Zf Variance. See Field Functions.

ECFM-CLEH Properties

Convection

In transport equations, you can choose from a range of schemes that calculate the convection term at a cell face. This calculation requires Simcenter STAR-CCM+ to compute the face value of a quantity from the surrounding cell values. The method used for computing this face value has a profound effect on the stability and accuracy of the numerical scheme. For guidance on selecting a convection scheme, see Convective Flux.

1st-order: First-order convection scheme.
2nd-order: Second-order convection scheme.

Start Time of ECFM

Time at which ECFM combustion begins.

ECFM Fuels

The fuel selection for ECFM combustion. Any fuel containing C, H, O, or N is suitable.

Combustion Reset Time

Time at which species and tracers are transferred from burnt gases to exhaust gas recirculation (EGR). This allows all combustion progress variables and the flame surface density to return back to 0 after the reset for the next cycle.

Combustion Reset Option

Controls how combustion reset is performed for multi-cycle analysis.

Off
Enthalpy Conservation
Pressure Conservation
Temperature Conservation

Secondary Gradients

There are two sources of secondary gradients in Simcenter STAR-CCM+ flow solvers:

boundary secondary gradients for diffusion
interior secondary gradients for diffusion at cell faces

Use this property to control which gradients are included in the solver. On gives both gradients while Off excludes them. Interior Only and Boundaries Only select the corresponding gradients.

Flow Boundary Diffusion

When activated, this property includes the flow-boundary diffusion fluxes (or viscous fluxes for flow models) as given by Eqn. (899). This property is activated by default.

ZF Variance Computed

Solves total conditional fuels mass fraction variance.

Coefficient GapCmin

Main premix zone transfer coefficient.

Option GapCminRelax

Relaxation of main premix zone transfer coefficient (only available with Fuel Saturation Distribution Model).

Coefficient BtPremLim

Burning rate limit for premix transfer.

Coefficient RatioUmLim

Unmixed fuel limit coefficient for premixed mode (PM) to post-oxidation (POSTOX) transfer.

Coefficient DiffSwLimPm

Fuel tracer gradient limit for premixed mode (PM) to post-oxidation (POSTOX) transfer.

Coefficient Ktrans

Transfer coefficient proportional to premixed mode (PM) burning rate.

Coefficient KtPstx

Premixed mode (PM) to post-oxidation (POSTOX) transfer rate for low premix burning rate.

Coefficient KtCleh

Premixed mode (PM) to diffusion (DIFF) transfer coefficient for low premix burning rate.

Coefficient IFC Equilibrium

Proportion of infinite fast combustion (IFC) limit in fuel equilibrium value.

AI Table Input Temperature Parameter

Input temperature parameter (0 to 1) for auto-ignition table.

Parameter of FSD Creation by Auto-Ignition

Parameter of flame surface density (FSD) creation by auto-ignition.

Burnt Fuel Mass Fraction Limit Allowing FSD Creation by AI

Burnt fuel mass fraction limit allowing flame surface density creation by auto-ignition.

Boundary Settings

Applies to Inlet boundary types. Applies to Outlet boundary types when Backflow Specification is set to Specified Scalars.

Fuel/Oxidizer Mixing State Specification: At the domain boundaries, allows you to specify if the fuel and oxidizer are unmixed or premixed at the subgrid level. Premixed is the default. For a fuel, for example H2 fuel, that is introduced through an inlet boundary as a gas phase, you are advised to set this property to an unmixed state.

ECFM-CLEH Combustion Solver

Under-Relaxation Factor: In order to promote convergence, this property is used to under-relax changes of the solution during the iterative process. If residuals show solution divergence or do not decrease, reduce the under-relaxation factor.
Verbosity: Allows you to choose how much information Simcenter STAR-CCM+ reports in the Output window while the simulation is running. This property is useful for debugging problems when they occur. The available options are None, Low, and High.
Solver Frozen: When On, the solver does not update any quantity during an iteration. It is Off by default. This is a debugging option that can result in non-recoverable errors and wrong solutions due to missing storage. See Finite Volume Solvers Reference for details.
Reconstruction Frozen: When On, Simcenter STAR-CCM+ does not update reconstruction gradients with each iteration, but rather uses gradients from the last iteration in which they were updated. Activate Temporary Storage Retained in conjunction with this property. This property is Off by default.
Reconstruction Zeroed: When On, the solver sets reconstruction gradients to zero at the next iteration. This action means that face values used for upwinding (Eqn. (905)) and for computing cell gradients (Eqn. (917) and Eqn. (918)) become first-order estimates. This property is Off by default. If you turn this property Off after having it On, the solver recomputes the gradients on the next iteration.
Temporary Storage Retained: When On, Simcenter STAR-CCM+ retains additional field data that the solver generates during an iteration. The particular data retained depends on the solver, and becomes available as field functions during subsequent iterations. Off by default.

Mixing

Turbulent Mixing Rate Multiplier: Constant used to multiply the turbulent mixing rate.

Diffusion

Diffusion Zone Reaction Rate Multiplier: Coefficient used to multiply the diffusion combustion rate in Eqn. (3871).
Diffusion to Post-Oxidation Transfer Coefficient: Normalized fuel tracer gradient limit used to compute diffusion to post-oxidation zone transfer $T_{D F \to P S T X}^{Z_{F}}$ in Eqn. (3862), Eqn. (3866), and Eqn. (3867).
Minimum Equivalence Ratio Limit: Minimum value for the equivalence ratio $Φ$ in Eqn. (3333).

Post-Oxidation

Post-Oxidation Activation Temperature for Forward Reaction: ${E a}_{1}$ in Eqn. (3872).
Post-Oxidation Activation Temperature for Reverse Reaction: ${E a}_{2}$ in Eqn. (3872).
Post-Oxidation Pre-Exponential Factor for Forward Reaction: ${A r}_{1}$ in Eqn. (3872).
Temperature of Maximum Post-Oxidation Reaction Rate: $T$ in Eqn. (3872).
Minimum Post-Oxidation Reaction Rate: Minimum value for ${{\tilde{\dot{ω}}}_{f} |}_{P S T X}$ in Eqn. (3872).
CO-CO2 Kinetic Cut Off Temperature
Reaction Rate Multiplier for Equilibrium Progression: $C$ in Eqn. (3871).
Minimum Equivalence Ratio Limit: Minimum value for the equivalence ratio $Φ$ in Eqn. (3333).
Post-Oxidation CO-CO2 Kinetic Factor: $k_{2}$ in Eqn. (4040).

EGR Composition

[species] EGR Mass Fraction: $Z_{E G R}$ in Eqn. (3875) to Eqn. (3877).

Field Functions

AImode Combustion Heat Release Rate: Auto-ignition heat release rate (part of the premixed zone).
Burnt Density
Burnt Temperature: $T_{b}$ in Eqn. (3933).
DIFF mode Combustion Heat Release Rate: Heat release rate in the diffusion zone.
Diffusion Combustion Progress Variable: $\tilde{α}$ in Eqn. (3874).
Enthalpy of [species]: The enthalpy of the specified species.
Equivalence Ratio: $ϕ$ used to calculate laminar flame speed. See Flame Speed Calculations.
Exhaust Gas Recirculation Mass Fraction: $Z_{E G R}$ in Eqn. (3875), Eqn. (3876), and Eqn. (3877).
Exhaust Gas Recirculation Mole Fraction: $X_{e g r}$ in Eqn. (3946).
FPmode Combustion Heat Release Rate: Flame propagation heat release rate (part of the premixed zone).
Global Combustion Progress Variable: Mean combustion progress variable of the four combustion zones.
Input Equilibrium Library Temperature: The unburnt temperature that is used to enter the equilibrium library by taking into account heat losses from combustion.
Mass Fraction of [species]: The mass fraction, $Y_{i} = {m_{i} / m}_{m}$ , of species $i$ in mixture $m$ .
Molar Concentration of [species]: The molar concentration, $C_{i} = ρ_{m} Y_{i} / W_{i}$ , of species i in a mixture m, where $ρ_{m}$ is the mixture density, $Y_{i}$ is the species mass fraction, and $W_{i}$ is the species molecular weight.
Mole Fraction of [species]: The mole fraction, $X_{i} = Y_{i} W_{m} / W_{i}$ , of species i in a mixture m, where $Y_{i}$ is the species mass fraction, $W_{m}$ is the molecular weight of the mixture, and $W_{i}$ is the molecular weight of the species.
Molecular Weight of [species]: The molecular weight of the specified species.
PSTOXmode Combustion Heat Release Rate: Heat release rate in the post-oxidation zone.
SImode Combustion Heat Release Rate: Heat release rate from spark ignition.
Specific Heat of [species]: The specific heat of the given species.
Total Conditional Fuel Mass Fraction: Fuel mass fraction in the unburnt zone.
Unburnt Temperature: The conditional temperature in the unburnt gases. Allows you to construct the flame speed.
YfeqDIFFFuel Equilibrium Mass Fraction Factor: ECFM-CLEH equilibrium fuel mass fraction factor in the diffusion zone.
YfeqPMFuel Equilibrium Mass Fraction Factor: ECFM-CLEH equilibrium fuel mass fraction factor in the premixed zone.
YfeqPMLIMFuel Equilibrium Mass Fraction Factor: ECFM-CLEH equilibrium fuel mass fraction factor limit in the premixed zone, taking into account the proportion of fuel mass fraction that is added to the equilibrium fuel mass fraction from libraries.
YfeqPSTOXFuel Equilibrium Mass Fraction Factor: ECFM-CLEH equilibrium fuel mass fraction factor in the post-oxidation zone.
YuN2: Unburnt mass fraction of N2.
YuO2: Unburnt mass fraction of O2.
YuCO2: Unburnt mass fraction of CO2.
YuH2O: Unburnt mass fraction of H2O.
YuCO: Unburnt mass fraction of CO.
YuH2: Unburnt mass fraction of H2.
YuYMWCLEH: Mass fraction of ECFM-CLEH virtual species—representing all complex chemistry species that are not taken into account by ECFM-CLEH, in order to recover the correct complex mixture molecular weight.
Zf Segregation Factor: Fuel tracer segregation factor.
Zf Variance: Fuel tracer turbulent fluctuation variance.