class CEA():
def __init__(self, fuel, oxidiser, chamber_pressure):
"""[summary]
Calcualtes hot gas properties using CEA and converts to SI units. If errors occur with FORTRAN, resart and try again!
:param chamber_pressure in [Pa]
:type fuel = string
:type oxidiser = string
"""
self.chamber_pressure = chamber_pressure
self.imperial_pressure = 0.000145038 * self.chamber_pressure #conversion to psia
self.ispObj = CEA_Obj(oxName=oxidiser, fuelName=fuel)
self.ispObj.get_full_cea_output()
def chamber_gas_properties(self, mixture_ratio, expansion_ratio):
self.Cp, self.visc, self.cond, self.Pr = self.ispObj.get_Chamber_Transport(
Pc=self.imperial_pressure, MR=mixture_ratio, frozen=1)
self.MW, self.gamma = self.ispObj.get_Chamber_MolWt_gamma(
Pc=self.imperial_pressure, MR=mixture_ratio, eps=expansion_ratio)
def throat_gas_properties(self, mixture_ratio, expansion_ratio):
self.Cp, self.visc, self.cond, self.Pr = self.ispObj.get_Throat_Transport(
Pc=self.imperial_pressure, MR=mixture_ratio, frozen=1)
self.MW, self.gamma = self.ispObj.get_Throat_MolWt_gamma(
Pc=self.imperial_pressure, MR=mixture_ratio, eps=expansion_ratio)
def exit_gas_properties(self, mixture_ratio, expansion_ratio):
self.Cp, self.visc, self.cond, self.Pr = self.ispObj.get_Exit_Transport(
Pc=self.imperial_pressure, MR=mixture_ratio, frozen=1)
self.MW, self.gamma = self.ispObj.get_exit_MolWt_gamma(
Pc=self.imperial_pressure, MR=mixture_ratio, eps=expansion_ratio)
def metric_cea_output(self, location, mixture_ratio, expansion_ratio):
if location == 'chamber':
self.chamber_gas_properties(mixture_ratio, expansion_ratio)
elif location == 'throat':
self.throat_gas_properties(mixture_ratio, expansion_ratio)
elif location == 'exit':
self.exit_gas_properties(mixture_ratio, expansion_ratio)
else:
raise ValueError(
'Invalid location, use "chamber," "throat" or "exit"')
self.isp, self.cstar, _ = self.ispObj.getFrozen_IvacCstrTc(
Pc=self.imperial_pressure, MR=mixture_ratio, eps=expansion_ratio)
self.cstar = self.cstar * 0.3048 # coversion to m/s
self.mole_fractions = self.ispObj.get_SpeciesMoleFractions(
Pc=self.imperial_pressure,
MR=mixture_ratio,
eps=expansion_ratio,
frozen=0,
frozenAtThroat=0,
min_fraction=5e-05)
self.Cp = self.Cp * 4186.8 # coversion to J/gk/K
self.mu = self.visc * 0.0001 # coversion to Pa*s
self.k = self.cond * 418.4e-3 # coversion to W/m/K
self.T_static = self.ispObj.get_Tcomb(
Pc=self.imperial_pressure,
MR=mixture_ratio) * 0.555556 # coversion to K
eps=40.0)
cpFch, visFch, conFch, prFch = ispObj.get_Chamber_Transport(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1)
cpEth, visEth, conEth, prEth = ispObj.get_Throat_Transport(Pc=1000.0,
MR=6.0,
eps=40.0)
cpFth, visFth, conFth, prFth = ispObj.get_Throat_Transport(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1)
cpEex, visEex, conEex, prEex = ispObj.get_Exit_Transport(Pc=1000.0,
MR=6.0,
eps=40.0)
cpFex, visFex, conFex, prFex = ispObj.get_Exit_Transport(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1)
sOut = """ Calling Transport Functions.
VISC,MILLIPOISE %6.4f %6.4f %6.4f
VISC,MILLIPOISE %6.4f %6.4f %6.4f
WITH EQUILIBRIUM REACTIONS
Cp, CAL/(G)(K) %6.4f %6.4f %6.4f
CONDUCTIVITY %6.4f %6.4f %6.4f
PRANDTL NUMBER %6.4f %6.4f %6.4f
class CEA_Obj(object):
"""
RocketCEA wraps the NASA FORTRAN CEA code to calculate Isp, cstar, and Tcomb
This object wraps the English unit version of CEA_Obj to enable desired user units.
"""
def __init__(self,
propName='',
oxName='',
fuelName='',
useFastLookup=0,
makeOutput=0,
isp_units='sec',
cstar_units='ft/sec',
pressure_units='psia',
temperature_units='degR',
sonic_velocity_units='ft/sec',
enthalpy_units='BTU/lbm',
density_units='lbm/cuft',
specific_heat_units='BTU/lbm degR',
viscosity_units='millipoise',
thermal_cond_units='mcal/cm-K-s',
fac_CR=None,
make_debug_prints=False):
"""::
#: RocketCEA wraps the NASA FORTRAN CEA code to calculate Isp, cstar, and Tcomb
#: This object wraps the English unit version of CEA_Obj to enable desired user units.
#: Same as CEA_Obj with standard units except, input and output units can be specified.
#: parameter default options
#: isp_units = 'sec', # N-s/kg, m/s, km/s
#: cstar_units = 'ft/sec', # m/s
#: pressure_units = 'psia', # MPa, KPa, Pa, Bar, Atm, Torr
#: temperature_units = 'degR', # K, C, F
#: sonic_velocity_units = 'ft/sec', # m/s
#: enthalpy_units = 'BTU/lbm', # J/g, kJ/kg, J/kg, kcal/kg, cal/g
#: density_units = 'lbm/cuft', # g/cc, sg, kg/m^3
#: specific_heat_units = 'BTU/lbm degR' # kJ/kg-K, cal/g-C, J/kg-K (# note: cal/g K == BTU/lbm degR)
#: viscosity_units = 'millipoise' # lbf-sec/sqin, lbf-sec/sqft, lbm/ft-sec, poise, centipoise
#: thermal_cond_units = 'mcal/cm-K-s' # millical/cm-degK-sec, BTU/hr-ft-degF, BTU/s-in-degF, cal/s-cm-degC, W/cm-degC
#: fac_CR, Contraction Ratio of finite area combustor (None=infinite)
#: if make_debug_prints is True, print debugging info to terminal.
"""
self.isp_units = isp_units
self.cstar_units = cstar_units
self.pressure_units = pressure_units
self.temperature_units = temperature_units
self.sonic_velocity_units = sonic_velocity_units
self.enthalpy_units = enthalpy_units
self.density_units = density_units
self.specific_heat_units = specific_heat_units
self.viscosity_units = viscosity_units
self.thermal_cond_units = thermal_cond_units
self.fac_CR = fac_CR
# Units objects for input/output (e.g. Pc and Pamb)
self.Pc_U = get_units_obj('psia', pressure_units)
# units of output quantities
self.isp_U = get_units_obj('sec', isp_units)
self.cstar_U = get_units_obj('ft/sec', cstar_units)
self.temperature_U = get_units_obj('degR', temperature_units)
self.sonic_velocity_U = get_units_obj('ft/sec', sonic_velocity_units)
self.enthalpy_U = get_units_obj('BTU/lbm', enthalpy_units)
self.density_U = get_units_obj('lbm/cuft', density_units)
self.specific_heat_U = get_units_obj('BTU/lbm degR',
specific_heat_units)
self.viscosity_U = get_units_obj('millipoise', viscosity_units)
self.thermal_cond_U = get_units_obj('mcal/cm-K-s', thermal_cond_units)
self.cea_obj = CEA_Obj_default(propName=propName,
oxName=oxName,
fuelName=fuelName,
useFastLookup=useFastLookup,
makeOutput=makeOutput,
fac_CR=fac_CR,
make_debug_prints=make_debug_prints)
self.desc = self.cea_obj.desc
def get_IvacCstrTc(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
IspVac, Cstar, Tcomb = self.cea_obj.get_IvacCstrTc(Pc=Pc,
MR=MR,
eps=eps)
IspVac = self.isp_U.dval_to_uval(IspVac)
Cstar = self.cstar_U.dval_to_uval(Cstar)
Tcomb = self.temperature_U.dval_to_uval(Tcomb)
return IspVac, Cstar, Tcomb
def getFrozen_IvacCstrTc(self,
Pc=100.0,
MR=1.0,
eps=40.0,
frozenAtThroat=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
IspFrozen, Cstar, Tcomb = self.cea_obj.getFrozen_IvacCstrTc(
Pc=Pc, MR=MR, eps=eps, frozenAtThroat=frozenAtThroat)
IspFrozen = self.isp_U.dval_to_uval(IspFrozen)
Cstar = self.cstar_U.dval_to_uval(Cstar)
Tcomb = self.temperature_U.dval_to_uval(Tcomb)
return IspFrozen, Cstar, Tcomb
def get_IvacCstrTc_exitMwGam(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
IspVac, Cstar, Tcomb, mw, gam = self.cea_obj.get_IvacCstrTc_exitMwGam(
Pc=Pc, MR=MR, eps=eps)
IspVac = self.isp_U.dval_to_uval(IspVac)
Cstar = self.cstar_U.dval_to_uval(Cstar)
Tcomb = self.temperature_U.dval_to_uval(Tcomb)
return IspVac, Cstar, Tcomb, mw, gam
def get_IvacCstrTc_ChmMwGam(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
IspVac, Cstar, Tcomb, mw, gam = self.cea_obj.get_IvacCstrTc_ChmMwGam(
Pc=Pc, MR=MR, eps=eps)
IspVac = self.isp_U.dval_to_uval(IspVac)
Cstar = self.cstar_U.dval_to_uval(Cstar)
Tcomb = self.temperature_U.dval_to_uval(Tcomb)
return IspVac, Cstar, Tcomb, mw, gam
def get_IvacCstrTc_ThtMwGam(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
IspVac, Cstar, Tcomb, mw, gam = self.cea_obj.get_IvacCstrTc_ThtMwGam(
Pc=Pc, MR=MR, eps=eps)
IspVac = self.isp_U.dval_to_uval(IspVac)
Cstar = self.cstar_U.dval_to_uval(Cstar)
Tcomb = self.temperature_U.dval_to_uval(Tcomb)
return IspVac, Cstar, Tcomb, mw, gam
def __call__(self, Pc=100.0, MR=1.0, eps=40.0):
return self.get_Isp(Pc=Pc, MR=MR, eps=eps)
def get_Isp(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
IspVac = self.cea_obj.get_Isp(Pc=Pc, MR=MR, eps=eps)
IspVac = self.isp_U.dval_to_uval(IspVac)
return IspVac
def get_Cstar(self, Pc=100.0, MR=1.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Cstar = self.cea_obj.get_Cstar(Pc=Pc, MR=MR)
Cstar = self.cstar_U.dval_to_uval(Cstar)
return Cstar
def get_Tcomb(self, Pc=100.0, MR=1.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Tcomb = self.cea_obj.get_Tcomb(Pc=Pc, MR=MR)
Tcomb = self.temperature_U.dval_to_uval(Tcomb)
return Tcomb
def get_PcOvPe(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_PcOvPe(Pc=Pc, MR=MR, eps=eps)
def get_eps_at_PcOvPe(self, Pc=100.0, MR=1.0, PcOvPe=1000.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_eps_at_PcOvPe(Pc=Pc, MR=MR, PcOvPe=PcOvPe)
def get_Throat_PcOvPe(self, Pc=100.0, MR=1.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_Throat_PcOvPe(Pc=Pc, MR=MR)
def get_MachNumber(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_MachNumber(Pc=Pc, MR=MR, eps=eps)
def get_Temperatures(self,
Pc=100.0,
MR=1.0,
eps=40.0,
frozen=0,
frozenAtThroat=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
tempList = self.cea_obj.get_Temperatures(Pc=Pc,
MR=MR,
eps=eps,
frozen=frozen,
frozenAtThroat=frozenAtThroat)
for i, T in enumerate(tempList):
tempList[i] = self.temperature_U.dval_to_uval(T)
return tempList # Tc, Tthroat, Texit
def get_SonicVelocities(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
sonicList = self.cea_obj.get_SonicVelocities(Pc=Pc, MR=MR, eps=eps)
for i, S in enumerate(sonicList):
sonicList[i] = self.sonic_velocity_U.dval_to_uval(S)
return sonicList # Chamber, Throat, Exit
def get_Chamber_SonicVel(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
sonicVel = self.cea_obj.get_Chamber_SonicVel(Pc=Pc, MR=MR, eps=eps)
sonicVel = self.sonic_velocity_U.dval_to_uval(sonicVel)
return sonicVel
def get_Enthalpies(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
hList = self.cea_obj.get_Enthalpies(Pc=Pc, MR=MR, eps=eps)
for i, H in enumerate(hList):
hList[i] = self.enthalpy_U.dval_to_uval(H)
return hList
def get_SpeciesMassFractions(self,
Pc=100.0,
MR=1.0,
eps=40.0,
frozen=0,
frozenAtThroat=0,
min_fraction=0.000005):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
molWtD, massFracD = self.cea_obj.get_SpeciesMassFractions(
Pc=Pc,
MR=MR,
eps=eps,
frozenAtThroat=frozenAtThroat,
min_fraction=min_fraction)
return molWtD, massFracD
def get_SpeciesMoleFractions(self,
Pc=100.0,
MR=1.0,
eps=40.0,
frozen=0,
frozenAtThroat=0,
min_fraction=0.000005):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
molWtD, moleFracD = self.cea_obj.get_SpeciesMoleFractions(
Pc=Pc,
MR=MR,
eps=eps,
frozenAtThroat=frozenAtThroat,
min_fraction=min_fraction)
return molWtD, moleFracD
def get_Chamber_H(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
H = self.cea_obj.get_Chamber_H(Pc=Pc, MR=MR, eps=eps)
return self.enthalpy_U.dval_to_uval(H)
def get_Densities(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
dList = self.cea_obj.get_Densities(Pc=Pc, MR=MR, eps=eps)
for i, d in enumerate(dList):
dList[i] = self.density_U.dval_to_uval(d)
return dList
def get_Chamber_Density(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
H = self.cea_obj.get_Chamber_Density(Pc=Pc, MR=MR, eps=eps)
return self.density_U.dval_to_uval(H)
def get_HeatCapacities(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
cpList = self.cea_obj.get_HeatCapacities(Pc=Pc,
MR=MR,
eps=eps,
frozen=frozen)
for i, cp in enumerate(cpList):
cpList[i] = self.specific_heat_U.dval_to_uval(cp)
return cpList
def get_Chamber_Cp(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Cp = self.cea_obj.get_Chamber_Cp(Pc=Pc, MR=MR, eps=eps)
return self.specific_heat_U.dval_to_uval(Cp)
def get_Throat_Isp(self, Pc=100.0, MR=1.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Isp = self.cea_obj.get_Throat_Isp(Pc=Pc, MR=MR)
Isp = self.isp_U.dval_to_uval(Isp)
return Isp
def get_Chamber_MolWt_gamma(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_Chamber_MolWt_gamma(Pc=Pc, MR=MR, eps=eps)
def get_Throat_MolWt_gamma(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_Throat_MolWt_gamma(Pc=Pc, MR=MR, eps=eps)
def get_exit_MolWt_gamma(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_exit_MolWt_gamma(Pc=Pc, MR=MR, eps=eps)
def get_eqratio(self, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
return self.cea_obj.get_eqratio(Pc=Pc, MR=MR, eps=eps)
def getMRforER(self, ERphi=None, ERr=None):
return self.cea_obj.getMRforER(ERphi=ERphi, ERr=ERr)
def get_description(self):
return self.cea_obj.get_description()
def estimate_Ambient_Isp(self,
Pc=100.0,
MR=1.0,
eps=40.0,
Pamb=14.7,
frozen=0,
frozenAtThroat=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Pamb = self.Pc_U.uval_to_dval(Pamb) # convert user units to psia
IspAmb, mode = self.cea_obj.estimate_Ambient_Isp(
Pc=Pc,
MR=MR,
eps=eps,
Pamb=Pamb,
frozen=frozen,
frozenAtThroat=frozenAtThroat)
IspAmb = self.isp_U.dval_to_uval(IspAmb)
return IspAmb, mode
def get_PambCf(self, Pamb=14.7, Pc=100.0, MR=1.0, eps=40.0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Pamb = self.Pc_U.uval_to_dval(Pamb) # convert user units to psia
CFcea, CF, mode = self.cea_obj.get_PambCf(Pamb=Pamb,
Pc=Pc,
MR=MR,
eps=eps)
return CFcea, CF, mode
def getFrozen_PambCf(self,
Pamb=0.0,
Pc=100.0,
MR=1.0,
eps=40.0,
frozenAtThroat=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Pamb = self.Pc_U.uval_to_dval(Pamb) # convert user units to psia
CFcea, CFfrozen, mode = self.cea_obj.getFrozen_PambCf(
Pamb=Pamb, Pc=Pc, MR=MR, eps=eps, frozenAtThroat=frozenAtThroat)
return CFcea, CFfrozen, mode
def get_Chamber_Transport(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Cp, visc, cond, Prandtl = self.cea_obj.get_Chamber_Transport(
Pc=Pc, MR=MR, eps=eps, frozen=frozen)
#Cp = Cp * 8314.51 / 4184.0 # convert into BTU/lbm degR
Cp = self.specific_heat_U.dval_to_uval(Cp)
visc = self.viscosity_U.dval_to_uval(visc)
cond = self.thermal_cond_U.dval_to_uval(cond)
return Cp, visc, cond, Prandtl
def get_Throat_Transport(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Cp, visc, cond, Prandtl = self.cea_obj.get_Throat_Transport(
Pc=Pc, MR=MR, eps=eps, frozen=frozen)
#Cp = Cp * 8314.51 / 4184.0 # convert into BTU/lbm degR
Cp = self.specific_heat_U.dval_to_uval(Cp)
visc = self.viscosity_U.dval_to_uval(visc)
cond = self.thermal_cond_U.dval_to_uval(cond)
return Cp, visc, cond, Prandtl
def get_Exit_Transport(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0):
Pc = self.Pc_U.uval_to_dval(Pc) # convert user units to psia
Cp, visc, cond, Prandtl = self.cea_obj.get_Exit_Transport(
Pc=Pc, MR=MR, eps=eps, frozen=frozen)
Cp = Cp * 8314.51 / 4184.0 # convert into BTU/lbm degR
Cp = self.specific_heat_U.dval_to_uval(Cp)
visc = self.viscosity_U.dval_to_uval(visc)
cond = self.thermal_cond_U.dval_to_uval(cond)
return Cp, visc, cond, Prandtl
class CEA:
def __init__(self, oxName, fuelName):
self.oxName = oxName
self.fuelName = fuelName
# dictionary containing the standard heat of formation for all species in [kJ/mol]
# you can find this data in thermo.inp in the rocketCEA library folder
self.heatDict = {
"ABS": 62.719,
"Acrylic": 382.0,
"N2O": 82.05,
"LO2": 0,
"*CO": -110.53,
"*CO2": -393.5,
"*H": 217.998,
"HCO": 42.397,
"HO2": 12.02,
"*H2": 0,
"C(gr)": 0,
"H2O": -241.826,
"*N": 472.680,
"*NO": 91.271,
"*N2": 0,
"*O": 249.175,
"*OH": 37.278,
"*O2": 0,
"COOH": -213,
"H2O2": -135.88,
"O3": 141.8,
"CH3": 146.658,
"CH4": -74.6,
"C2H2,acetylene": 228.2,
"CH2CO,ketene": -49.576,
"C2H4": 52.5,
"HCN": 133.082,
"HNC": 194.378,
"NH3": -54.752,
"CH3CN": 31.38,
"C4H2,butadiyne": 450,
"C2N2": 283.209,
"*CN": 438.683,
"HNCO": -118.056,
"C3H3,2-propynl": 331.8,
"HNO": 102.032,
"NO2": 34.193,
"C2H6": -103.819,
"HCHO,formaldehy": -108.58,
"C3H6,propylene": 20.0
}
# Dictionary holding molar masses for reactants [g/mol]
self.MMDict = {
"LO2": 15.999,
"N2O": 44.013,
"ABS": 57.07,
"Acrylic": 100.12
}
self.addCustomSpecies()
self.C = CEA_Obj(oxName=oxName, fuelName=fuelName)
def getOutput(self, Pc, OFRatio, ExpansionRatio, printOutput):
output = self.C.get_full_cea_output(Pc=Pc, MR=OFRatio, eps=ExpansionRatio, short_output=0, output='siunits')
if printOutput:
print(output)
def getChamberEquilibrium(self, Pc, OFRatio, ExpansionRatio, location):
# gets all of the properties of the thingy (make sure not to ask for too much, you will upset him)
# location: 0-injector (not supported) 1-chamber 2-throat 3-exit
if location == 0:
print("ERROR: properties at injector not supported")
elif location == 1:
self.Isp_Vac, self.C_star, self.T_flame, self.MW, self.gamma = self.C.get_IvacCstrTc_ChmMwGam(Pc=Pc, MR=OFRatio, eps=ExpansionRatio) # get ISP [s], C* [ft/s], T [R], MW [g/mol], gamma [-]
self.Cp, self.visc, self.thermCond, self.prandtl = self.C.get_Chamber_Transport(Pc, OFRatio, ExpansionRatio) # get heat capacity [cal/g*K], viscosity[milliPoise], thermal conductivity [mcal/cm*s*K], Prandtl Number [-]
elif location == 2:
self.Isp_Vac, self.C_star, self.T_flame, self.MW, self.gamma = self.C.get_IvacCstrTc_ThtMwGam(Pc=Pc, MR=OFRatio, eps=ExpansionRatio) # get ISP [s], C* [ft/s], T [R], MW [g/mol], gamma [-]
self.Cp, self.visc, self.thermCond, self.prandtl = self.C.get_Throat_Transport(Pc, OFRatio, ExpansionRatio) # get heat capacity [cal/g*K], viscosity[milliPoise], thermal conductivity [mcal/cm*s*K], Prandtl Number [-]
elif location == 3:
self.Isp_Vac, self.C_star, self.T_flame, self.MW, self.gamma = self.C.get_IvacCstrTc_exitMwGam(Pc=Pc, MR=OFRatio, eps=ExpansionRatio) # get ISP [s], C* [ft/s], T [R], MW [g/mol], gamma [-]
self.Cp, self.visc, self.thermCond, self.prandtl = self.C.get_Exit_Transport(Pc, OFRatio, ExpansionRatio) # get heat capacity [cal/g*K], viscosity[milliPoise], thermal conductivity [mcal/cm*s*K], Prandtl Number [-]
else:
print("ERROR: location index out of bounds")
self.T_flame = self.T_flame/1.8 # convert to Kelvin
self.C_star = self.C_star / 3.28084 # convert characteristic velocity to [m/s]
self.Cp = self.Cp * 4.186798 # get specific heat capacity [j/g*C]
self.visc = self.visc/1000 # convert from milliPoise to Poise
self.thermCond = self.thermCond * 418000 # convert to [W/m*K]
return self.Isp_Vac, self.C_star, self.T_flame, self.MW, self.gamma, self.Cp, self.visc, self.thermCond, self.prandtl
def getReactionHeat(self, Pc, OFRatio, ExpansionRatio, location):
h_products = self.getProductsEnthalpy(Pc, OFRatio, ExpansionRatio, location)
h_fuel = self.findHeatOfFormation(self.fuelName)/self.MMDict[self.fuelName]
h_ox = self.findHeatOfFormation(self.oxName)/self.MMDict[self.oxName]
X_fuel = 1/(OFRatio+1) # fuel mass fraction
X_ox = OFRatio/(OFRatio+1) # oxidizer mass fraction
h_reactants = X_fuel*h_fuel + X_ox*h_ox
Q_total = h_products - h_reactants # assuming adiabatic circumstances, Q_total = deltaH
return Q_total
def getProductsEnthalpy(self, Pc, OFRatio, ExpansionRatio, location):
# calculates the enthalpy per gram of products
# location: 0-injector 1-chamber 2-throat 3-exit
molarMass, massFraction = self.C.get_SpeciesMassFractions(Pc=Pc, MR=OFRatio, eps=ExpansionRatio)
# convert molarMass and massFraction into lists with species name in first column, and data in second
molarMass = list(molarMass), list(molarMass.values())
massFraction = list(massFraction), list(massFraction.values())
# create an array containing the standard heat of formations of all species
h_f = molarMass
h_products = 0
for i in range(len(molarMass[0])):
h_f[1][i] = self.findHeatOfFormation(molarMass[0][i]) / molarMass[1][i] # heat of formation [kJ/g]
h_products += h_f[1][i] * massFraction[1][i][location]
return h_products
def findHeatOfFormation(self, species):
try:
return self.heatDict[species]
except:
print("ERROR:", species, "is not defined in heat of formation dictionary. Look in the init of the CEA class")
def addCustomSpecies(self):
# Add custom species to CEA
card_str = """
fuel ABS C 3.85 H 4.85 N 0.43 wt%=100.00
h,cal=14990 t(k)=298.15 rho=0.975
"""
add_new_fuel('ABS', card_str)
card_str = """
fuel Acrylic C 5 H 8 O 2 wt%=100.00
h,cal=91396 t(k)=298.15 rho=1.18
"""
add_new_fuel('Acrylic', card_str)
