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
def test_full_cea_output(self):
C = CEA_Obj(oxName="LOX", fuelName="LH2", fac_CR=None)
s = C.get_full_cea_output(Pc=1000.0, MR=6.0, eps=40.0)
#print( s )
ipos = s.find('Isp, LB-SEC/LB 154.4 431.2')
self.assertGreater(ipos, 4000)
del C
from rocketcea.cea_obj import CEA_Obj ispObj = CEA_Obj(oxName='LOX', fuelName='LH2', fac_CR=2.5) s = ispObj.get_full_cea_output(Pc=1000.0, MR=6.0, eps=40.0) print(s)
from rocketcea.cea_obj import CEA_Obj
ispObj = CEA_Obj(oxName='LOX', fuelName='LH2')
s = ispObj.get_full_cea_output(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1,
frozenAtThroat=0,
short_output=1)
print(s)
from rocketcea.cea_obj import CEA_Obj
Pc = 40.0
eps = 5.0
ispObj = CEA_Obj(oxName='GOX', fuelName='GH2')
s = ispObj.get_full_cea_output(Pc=Pc,
MR=5.0,
eps=eps,
frozen=0,
frozenAtThroat=0,
short_output=1,
show_transport=1)
print(s)
print("""==================================""")
print(ispObj.get_HeatCapacities(Pc=Pc, MR=.25, eps=eps))
print(ispObj.get_HeatCapacities(Pc=Pc, MR=5.0, eps=eps))
"""
figure out Pcinj_face to get desired Pcomb_end (100 atm in example)
"""
from rocketcea.cea_obj import CEA_Obj
cr = 2.5 # contraction ratio
ispObj = CEA_Obj(oxName='LOX', fuelName='LH2', fac_CR=cr)
# Use 100 atm to make output easy to read
Pc = 100.0 * 14.6959
# use correlation to make 1st estimate of Pcinj_face / Pcomb_end
PinjOverPcomb = 1.0 + 0.54 / cr**2.2
# use RocketCEA to refine initial estimate
PinjOverPcomb = ispObj.get_Pinj_over_Pcomb(Pc=Pc * PinjOverPcomb, MR=6.0)
# print results (noting that "COMB END" == 100.00 atm)
s = ispObj.get_full_cea_output(Pc=Pc * PinjOverPcomb, MR=6.0, eps=40.0)
print(s)
from rocketcea.cea_obj import CEA_Obj, add_new_fuel, add_new_oxidizer, add_new_propellant
# ==========
card_str = """
name H2O2(L) H 2 O 2 wt%=100.00
h,cal=-44880.0 t(k)=298.15 rho.g/cc=1.407
"""
add_new_propellant('MyProp', card_str)
C = CEA_Obj(propName="MyProp")
s = C.get_full_cea_output(Pc=250.0, eps=40.0, short_output=1)
print(s)
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)
print( 'cal_per_mole:%g'%cal_per_mole )
card_str = """
oxid Peroxide_90h2o2 H %g O %g wt%%=100.0
h,cal=%g t(k)=298.15 rho,g/cc = 1.395
"""%(frac_h, frac_ox, cal_per_mole)
print( card_str )
# ============== Add the new card to RocketCEA ==============
add_new_oxidizer( 'Peroxide_90h2o2', card_str )
# ============= Make a sample run at nominal conditions ==========
# (gives exact same results as library Peroxide90)
C = CEA_Obj(propName="Peroxide_90h2o2")
s = C.get_full_cea_output( Pc = 1000.0,eps=2.0,short_output = 1)
print( s )
# =============== make plot ================
TvalL = []
IspL = []
for TdegR in range(500, 660, 10):
new_card = makeCardForNewTemperature(ceaName='Peroxide_90h2o2', newTdegR=TdegR, CpAve=0.66, MolWt=MolWtMixture)
ispObj = CEA_Obj( propName=new_card )
TvalL.append( TdegR )
IspL.append( ispObj(Pc=1000.0, eps=2.0 ) )
plot(TvalL, IspL, label='90% Peroxide', linewidth=2)
from rocketcea.cea_obj import CEA_Obj
ispObj = CEA_Obj(oxName='LOX', fuelName='LH2')
s = ispObj.get_full_cea_output(Pc=1000.0,
MR=6.0,
eps=40.0,
short_output=1,
show_transport=1)
print(s)
from rocketcea.cea_obj import CEA_Obj, add_new_fuel, add_new_oxidizer, add_new_propellant card_str = """ fuel NASA_RP-1 C 1.0 H 1.95 wt%=100.00 h,cal=-5907.672 t(k)=298.15 rho=.773 """ add_new_fuel( 'NASA_RP_1', card_str ) C = CEA_Obj(oxName="GOX", fuelName="NASA_RP_1") s = C.get_full_cea_output( Pc=1000.0, MR=3.0, eps=40.0, short_output=1) print( s )
from rocketcea.cea_obj import CEA_Obj, add_new_fuel, add_new_oxidizer, add_new_propellant
card_str = """
oxid N2O4(L) N 2 O 4 wt%=96.5
h,cal=-4676.0 t(k)=298.15
oxid SiO2 Si 1.0 O 2.0 wt%=3.5
h,cal=-216000.0 t(k)=298.15 rho=1.48
"""
add_new_oxidizer('GelN2O4', card_str)
# ==========
card_str = """
fuel CH6N2(L) C 1.0 H 6.0 N 2.0 wt%=60.00
h,cal=12900.0 t(k)=298.15 rho=.874
fuel AL AL 1.0 wt%=40.00
h,cal=0.0 t(k)=298.15 rho=0.1
"""
add_new_fuel('MMH_AL', card_str)
C = CEA_Obj(oxName="GelN2O4", fuelName="MMH_AL")
s = C.get_full_cea_output(Pc=1850.0, MR=0.7, eps=40.0, short_output=1)
print(s)
def createPropellant(wt1,wt2,wt3):
card_str = """
name H2O H 2 O 1 wt%={:.1f}
h,kj/mol=-285.8 t(k)=293.15
name Methanol C 1 H 4 O 1 wt%={:.1f}
h,kj/mol=-239.2 t(k)=293.15
name ADN H 4 N 4 O 4 wt%={:.1f}
h,kj/mol=-134.6 t(k)=293.15
""".format(wt1,wt2,wt3)
add_new_propellant("WaterMethanolADN_Mix",card_str)
def bar2psi(bar):
return bar*14.504
""" prepare fuel """
meth = 39
adn = 59
h2o = 2
createPropellant(h2o,meth,adn)
""" get full output """
chamber_pressure = 16
expansion_ratio = 60
temp = CEA_Obj(propName="WaterMethanolADN_Mix")
(isp,cstr,tc) = temp.getFrozen_IvacCstrTc(Pc=bar2psi(chamber_pressure),eps=expansion_ratio,frozenAtThroat=1)
print(isp,cstr,tc)
s = temp.get_full_cea_output( Pc=bar2psi(chamber_pressure), eps=expansion_ratio, frozen=1, frozenAtThroat=1)
with open("b4.out","w") as f:
f.write(s)
print(s)
from rocketcea.cea_obj import CEA_Obj
ispObj = CEA_Obj(oxName='LOX', fuelName='LH2')
s = ispObj.get_full_cea_output(
Pc=[1000, 2000], # number or list of chamber pressures
MR=[6.0, 7.0], # number or list of mixture ratios
PcOvPe=[100, 200], # number or list of Pc/Pexit
eps=[40.0, 60], # number or list of supersonic area ratios
subar=[3, 2], # number or list of subsonic area ratios
short_output=0, # 0 or 1 to control output length
pc_units='psia', # pc_units = 'psia', 'bar', 'atm', 'mmh'
output='siunits') # output = 'calories' or 'siunits'
print(s)
from rocketcea.cea_obj import CEA_Obj
C = CEA_Obj(oxName='LOX', fuelName='RP1')
full_cea = C.get_full_cea_output(Pc=100,
MR=1.0,
eps=None,
subar=None,
PcOvPe=100,
show_transport=1,
pc_units='bar',
output='KJ',
short_output=1)
print(
'this is the cea string:------------------------------------------------------------------------------------------------------------------'
)
print(full_cea)
from rocketcea.cea_obj import CEA_Obj ispObj = CEA_Obj(propName='Peroxide98') s = ispObj.get_full_cea_output(Pc=1000.0, eps=10.0) print(s)
from rocketcea.cea_obj import CEA_Obj
ispObj = CEA_Obj(oxName='LOX', fuelName='LH2')
s = ispObj.get_full_cea_output(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1,
frozenAtThroat=0,
short_output=0,
pc_units='psia',
show_mass_frac=True)
print(s)