Generic chemistry interface for Cantera

The generic chemistry interface for Cantera defines a number of common methods that are used for all Cantera-based simulations. These methods create and modify Cantera phase objects for sensitivity analysis.

Initialization function summary

cantera_utils.measurement_initialize(filename, chemistry_model)

Read a text file to initialize a batch of measurements

cantera_utils.measurement_initialize_pd(source, chemistry_model=None, **kwargs)

Read a database file in Excel into a Pandas dataframe, then process the dataframe into a batch of measurements

Parameters:source – The file that contains the experimental database.
Key chemistry_model:
 The Cantera chemistry model. It must be a chemistry model that can be used to make a Cantera phase object

Generic chemistry model method summary

CanteraChemistryModel(T, Patm, composition, …) A class for Cantera chemistry models.
CanteraChemistryModel.sensitivity(…[, tq]) Evaluates the sensitivity of the model value with respect to the model parameters
CanteraChemistryModel.get_parameter(parameter_id) Retrieves a model parameter’s value.
CanteraChemistryModel.perturb_parameter(…) Replaces a model parameter’s value by a new value.
CanteraChemistryModel.reset_model() Reset all model parameters to their original values
CanteraChemistryModel.get_model_parameter_info([…]) Gets the list of available parameters for this model
CanteraChemistryModel.prepare_chemistry([…]) Instantiate the Cantera chemistry model and get information about the reaction model.
CanteraChemistryModel.initialize_chemistry() Create the Cantera phase object and set its initial state
CanteraChemistryModel.blank_chemistry() Erase the Cantera phase object, Cantera reactor object, and Cantera simulation object.

Generic Cantera chemistry model class

class cantera_chemistry_model.CanteraChemistryModel(T, Patm, composition, chemistry_model, **kwargs)

A class for Cantera chemistry models.

Parameters:
  • T (float) – The unburned gas temperature in Kelvins
  • Patm (float) – The pressure in atmospheres (will be converted internally to Pa)
  • composition (str,ndarray(float)) – The composition of the unburned gas. Can be a float array or a Cantera composition string
  • chemistry_model (str) – The chemistry model for the flame. Must be a chemistry model that can be used to make a Cantera phase object
Key no_falloff:

If False, the falloff parameters for reactions will be available as active parameters (default True)
Key no_energies:
 

if False, the activation energies will be available as active parameters. (default True)

This is a class that implements certain common methods for the Cantera-based simulations in this package. It is a subclass of Model. It implements the following methods required by Model:

You cannot instantiate a member of this class because it does not have an evaluate() method.

It also includes the following methods that permit easier access to the Cantera objects that the model contains:

In addition, the method initialize_reactor() is provided as an abstract method. Subclasses of this class must define this method or else they cannot be instantiated.

sensitivity(perturbation, parameter_list, logfile, tq=True)

Evaluates the sensitivity of the model value with respect to the model parameters

Parameters:
  • perturbation (float) – The amount to perturb each parameter during the sensitivity analysis
  • parameter_list (array_like) – The list of parameters to perturb. This will be a list of parameter identifiers, which are usually ints or strs.
  • logfile (str) – The logging file that will contain the sensitivity calculation output.
Returns:

model_value,sensitivity_vector
Return type:

float,ndarray
get_parameter(parameter_id)

Retrieves a model parameter’s value.

This will retrive the parameter specified by parameter_id, which will be either a reaction pre-exponential factor or an activation energy.

Parameters:parameter_id (int) – The parameter identifier.
Returns:parameter_value
Return type:float
perturb_parameter(parameter_id, new_value)

Replaces a model parameter’s value by a new value.

This will replace a reaction’s pre-exponential factor or activation energy with a new value

Parameters:
  • parameter_id (int) – The parameter identifier.
  • new_value (float) – The amount to change the parameters value.
reset_model()

Reset all model parameters to their original values

This version works by erasing the chemistry and re-initializing it from the CTI file.

get_model_parameter_info(no_efficiencies=False, no_energy=False, no_falloff=False)

Gets the list of available parameters for this model

Parameters:
  • no_efficiencies – If True, then do not consider the third-body efficiencies as active parameters
  • no_energies – If True, then do not consider activation energies as active parameters
  • no_falloff – If True, then do not consider high- and low-pressure limits as active parameters
Returns:

model_parameter_info
Return type:

list of dicts
prepare_chemistry(no_efficiencies=True, no_energy=True, no_falloff=True, **kwargs)

Instantiate the Cantera chemistry model and get information about the reaction model. This is called during instantiation of the model and normally would not be called at any other time.

initialize_chemistry()

Create the Cantera phase object and set its initial state

This method does the following:

  • Checks to see if a Cantera Solution object exists that defined the thermodynamic state of the Cantera reactor, and creates that object if it does not exist
  • Sets the state of the Cantera Solution object to the state specified in self.initial
blank_chemistry()

Erase the Cantera phase object, Cantera reactor object, and Cantera simulation object.