def test_falloff(self):
r = ct.FalloffReaction('OH:2', 'H2O2:1')
r.high_rate = ct.Arrhenius(7.4e10, -0.37, 0.0)
r.low_rate = ct.Arrhenius(2.3e12, -0.9, -1700*1000*4.184)
r.falloff = ct.TroeFalloff((0.7346, 94, 1756, 5182))
r.efficiencies = {'AR':0.7, 'H2':2.0, 'H2O':6.0}
gas2 = ct.Solution(thermo='IdealGas', kinetics='GasKinetics',
species=self.species, reactions=[r])
gas2.TPX = self.gas.TPX
self.assertNear(gas2.forward_rate_constants[0],
self.gas.forward_rate_constants[20])
self.assertNear(gas2.net_rates_of_progress[0],
self.gas.net_rates_of_progress[20])
def _build_cantera_solution(cls, gdata):
p_ref = gdata['ref_pressure']
species_list = list()
for s in gdata['species']:
spec = gdata['species'][s]
ctspec = ct.Species(
s, ','.join(
[f'{k}:{spec["atom_map"][k]}' for k in spec['atom_map']]))
if spec['cp'][0] == 'constant':
Tmin, Tmax, T0, h0, s0, cp = spec['cp'][1:]
ctspec.thermo = ct.ConstantCp(Tmin, Tmax, p_ref,
list([T0, h0, s0, cp]))
elif spec['cp'][0] == 'NASA7':
Tmin, Tmid, Tmax, low_coeffs, high_coeffs = spec['cp'][1:]
coeffs = [Tmid] + high_coeffs + low_coeffs
ctspec.thermo = ct.NasaPoly2(Tmin, Tmax, p_ref, coeffs)
species_list.append(ctspec)
reaction_list = list()
for rxn in gdata['reactions']:
type, reactants_stoich, products_stoich, reversible = rxn[:4]
fwd_pre_exp_value, fwd_temp_exponent, fwd_act_energy = rxn[4:7]
fwd_rate = ct.Arrhenius(fwd_pre_exp_value, fwd_temp_exponent,
fwd_act_energy)
if type == 'simple' or type == 'simple-special':
ctrxn = ct.ElementaryReaction(reactants_stoich,
products_stoich)
ctrxn.rate = fwd_rate
elif type == 'three-body' or type == 'three-body-special':
ctrxn = ct.ThreeBodyReaction(reactants_stoich, products_stoich)
ctrxn.rate = fwd_rate
ctrxn.efficiencies = rxn[7]
ctrxn.default_efficiency = rxn[8]
elif type == 'Lindemann' or type == 'Lindemann-special':
ctrxn = ct.FalloffReaction(reactants_stoich, products_stoich)
ctrxn.efficiencies = rxn[7]
ctrxn.default_efficiency = rxn[8]
flf_pre_exp_value, flf_temp_exponent, flf_act_energy = rxn[
9:12]
ctrxn.high_rate = fwd_rate
ctrxn.low_rate = ct.Arrhenius(flf_pre_exp_value,
flf_temp_exponent,
flf_act_energy)
ctrxn.falloff = ct.Falloff()
elif type == 'Troe' or type == 'Troe-special':
ctrxn = ct.FalloffReaction(reactants_stoich, products_stoich)
ctrxn.efficiencies = rxn[7]
ctrxn.default_efficiency = rxn[8]
flf_pre_exp_value, flf_temp_exponent, flf_act_energy = rxn[
9:12]
troe_params = rxn[12]
ctrxn.high_rate = fwd_rate
ctrxn.low_rate = ct.Arrhenius(flf_pre_exp_value,
flf_temp_exponent,
flf_act_energy)
if len(troe_params) == 4 and abs(troe_params[3]) < 1e-300:
ctrxn.falloff = ct.TroeFalloff(troe_params[:3])
else:
ctrxn.falloff = ct.TroeFalloff(troe_params)
if 'special' in type:
ctrxn.orders = rxn[-1]
ctrxn.reversible = reversible
reaction_list.append(ctrxn)
return ct.Solution(thermo='IdealGas',
kinetics='GasKinetics',
species=species_list,
reactions=reaction_list)
def modify_reactions(self, coeffs, rxnNums=[]): # Only works for Arrhenius equations currently
if not rxnNums: # if rxnNums does not exist, modify all
rxnNums = range(len(coeffs))
else:
if isinstance(rxnNums, (float, int)): # if single reaction given, run that one
rxnNums = [rxnNums]
rxns_to_SRI = {}
for rxnNum in rxnNums:
rxn = self.gas.reaction(rxnNum)
rxnChanged = False
if type(rxn) in [ct.ElementaryReaction, ct.ThreeBodyReaction]:
for coefName in ['activation_energy', 'pre_exponential_factor', 'temperature_exponent']:
if coeffs[rxnNum][0][coefName] != eval(f'rxn.rate.{coefName}'):
rxnChanged = True
if rxnChanged: # Update reaction rate
A = coeffs[rxnNum][0]['pre_exponential_factor']
b = coeffs[rxnNum][0]['temperature_exponent']
Ea = coeffs[rxnNum][0]['activation_energy']
rxn.rate = ct.Arrhenius(A, b, Ea)
#elif type(rxn) is ct.PlogReaction:
# # Search for altered reactions, if found convert to SRI
# for n, rate in enumerate(rxn.rates):
# if rxnNum in rxns_to_SRI:
# break
# for coefName in ['activation_energy', 'pre_exponential_factor', 'temperature_exponent']:
# if coeffs[rxnNum][n][coefName] != eval(f'rate[1].{coefName}'):
# rxns_to_SRI[rxnNum] = 'SRI'
# break
# continue
elif type(rxn) is ct.FalloffReaction:
for key in ['low_rate', 'high_rate', 'falloff_parameters']:
if 'rate' in key:
for coefName in ['activation_energy', 'pre_exponential_factor', 'temperature_exponent']:
if coeffs[rxnNum][key][coefName] != eval(f'rxn.{key}.{coefName}'):
rxnChanged = True
A = coeffs[rxnNum][key]['pre_exponential_factor']
b = coeffs[rxnNum][key]['temperature_exponent']
Ea = coeffs[rxnNum][key]['activation_energy']
setattr(rxn, key, ct.Arrhenius(A, b, Ea))
break
else:
length_different = len(coeffs[rxnNum][key]) != len(rxn.falloff.parameters)
if length_different or (coeffs[rxnNum][key] != rxn.falloff.parameters).any():
rxnChanged = True
if coeffs[rxnNum]['falloff_type'] == 'Troe':
rxn.falloff = ct.TroeFalloff(coeffs[rxnNum][key])
else: # could also be SRI. For optimization this would need to be cast as Troe
rxn.falloff = ct.SriFalloff(coeffs[rxnNum][key])
elif type(rxn) is ct.ChebyshevReaction:
pass
else:
continue
if rxnChanged:
self.gas.modify_reaction(rxnNum, rxn)
def set_mechanism(self, mech_dict, species_dict={}, bnds=[]):
def get_Arrhenius_parameters(entry):
A = entry['pre_exponential_factor']
b = entry['temperature_exponent']
Ea = entry['activation_energy']
return A, b, Ea
if len(species_dict) == 0:
species = self.gas.species()
else:
species = []
for n in range(len(species_dict)):
s_dict = species_dict[n]
s = ct.Species(name=s_dict['name'],
composition=s_dict['composition'],
charge=s_dict['charge'],
size=s_dict['size'])
thermo = s_dict['type'](s_dict['T_low'], s_dict['T_high'],
s_dict['P_ref'], s_dict['coeffs'])
s.thermo = thermo
species.append(s)
# Set kinetics data
rxns = []
for rxnIdx in range(len(mech_dict)):
if 'ElementaryReaction' == mech_dict[rxnIdx]['rxnType']:
rxn = ct.ElementaryReaction(mech_dict[rxnIdx]['reactants'],
mech_dict[rxnIdx]['products'])
rxn.allow_negative_pre_exponential_factor = True
A, b, Ea = get_Arrhenius_parameters(
mech_dict[rxnIdx]['rxnCoeffs'][0])
rxn.rate = ct.Arrhenius(A, b, Ea)
elif 'ThreeBodyReaction' == mech_dict[rxnIdx]['rxnType']:
rxn = ct.ThreeBodyReaction(mech_dict[rxnIdx]['reactants'],
mech_dict[rxnIdx]['products'])
A, b, Ea = get_Arrhenius_parameters(
mech_dict[rxnIdx]['rxnCoeffs'][0])
rxn.rate = ct.Arrhenius(A, b, Ea)
rxn.efficiencies = mech_dict[rxnIdx]['rxnCoeffs'][0][
'efficiencies']
elif 'PlogReaction' == mech_dict[rxnIdx]['rxnType']:
rxn = ct.PlogReaction(mech_dict[rxnIdx]['reactants'],
mech_dict[rxnIdx]['products'])
rates = []
for plog in mech_dict[rxnIdx]['rxnCoeffs']:
pressure = plog['Pressure']
A, b, Ea = get_Arrhenius_parameters(plog)
rates.append((pressure, ct.Arrhenius(A, b, Ea)))
rxn.rates = rates
elif 'FalloffReaction' == mech_dict[rxnIdx]['rxnType']:
rxn = ct.FalloffReaction(mech_dict[rxnIdx]['reactants'],
mech_dict[rxnIdx]['products'])
# high pressure limit
A, b, Ea = get_Arrhenius_parameters(
mech_dict[rxnIdx]['rxnCoeffs']['high_rate'])
rxn.high_rate = ct.Arrhenius(A, b, Ea)
# low pressure limit
A, b, Ea = get_Arrhenius_parameters(
mech_dict[rxnIdx]['rxnCoeffs']['low_rate'])
rxn.low_rate = ct.Arrhenius(A, b, Ea)
# falloff parameters
if mech_dict[rxnIdx]['rxnCoeffs']['falloff_type'] == 'Troe':
falloff_param = mech_dict[rxnIdx]['rxnCoeffs'][
'falloff_parameters']
if falloff_param[-1] == 0.0:
falloff_param = falloff_param[0:-1]
rxn.falloff = ct.TroeFalloff(falloff_param)
else:
rxn.falloff = ct.SriFalloff(
mech_dict[rxnIdx]['rxnCoeffs']['falloff_parameters'])
rxn.efficiencies = mech_dict[rxnIdx]['rxnCoeffs'][
'efficiencies']
elif 'ChebyshevReaction' == mech_dict[rxnIdx]['rxnType']:
rxn = ct.ChebyshevReaction(mech_dict[rxnIdx]['reactants'],
mech_dict[rxnIdx]['products'])
rxn.set_parameters(Tmin=mech_dict['Tmin'],
Tmax=mech_dict['Tmax'],
Pmin=mech_dict['Pmin'],
Pmax=mech_dict['Pmax'],
coeffs=mech_dict['coeffs'])
rxn.duplicate = mech_dict[rxnIdx]['duplicate']
rxn.reversible = mech_dict[rxnIdx]['reversible']
rxn.allow_negative_orders = True
rxn.allow_nonreactant_orders = True
rxns.append(rxn)
self.gas = ct.Solution(thermo='IdealGas',
kinetics='GasKinetics',
species=species,
reactions=rxns)
self.set_rate_expression_coeffs(bnds) # set copy of coeffs
self.set_thermo_expression_coeffs() # set copy of thermo coeffs
