def test_getMRforER(self):
""" test call to getMRforER( ERphi=None, ERr=None) """
C = CEA_Obj(oxName="LOX", fuelName="MMH", fac_CR=None)
mr = C.getMRforER(ERphi=1.0, ERr=None)
self.assertAlmostEqual(mr, 1.7363572550114232, places=3)
mr = C.getMRforER(ERphi=None, ERr=1.0)
self.assertAlmostEqual(mr, 1.7363572550114232, places=3)
del C
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 MR_Temperature_Limits(object):
def __init__(self,
oxName='N2O4',
fuelName='MMH',
oxPcentL=None,
fuelPcentL=None,
TC_LIMIT=1000.0,
PcNominal=1000.0,
epsNominal=10.0,
MR_MIN=0.0,
MR_MAX=1000.0): # degR, psia
"""
For the nominal Pc and Area Ratio,
Find minimum and maximum mixture ratio where Tcombusion >= 1000 degR
"""
self.oxName = oxName
self.oxPcentL = oxPcentL
self.fuelName = fuelName
self.fuelPcentL = fuelPcentL
self.cea_fuelName = get_propellant_name(Name=fuelName,
PcentL=fuelPcentL)
self.cea_oxName = get_propellant_name(Name=oxName, PcentL=oxPcentL)
self.TC_LIMIT = TC_LIMIT
self.PcNominal = PcNominal
self.epsNominal = epsNominal
self.MR_MIN = MR_MIN
self.MR_MAX = MR_MAX
self.ispODEObj = CEA_Obj(fuelName=self.cea_fuelName,
oxName=self.cea_oxName,
useFastLookup=0,
fac_CR=None)
self.Stoich_MR = self.ispODEObj.getMRforER(ERphi=1.0)
#print( 'Stoich MR =',self.Stoich_MR,'for %s/%s'%(self.cea_oxName, self.cea_fuelName) )
self.find_min_mr()
self.find_max_mr()
def find_min_mr(self):
'''Find min mr where CEA Isp is Non-Zero AND Tc >= TC_LIMIT'''
isp = self.ispODEObj.get_Isp(Pc=self.PcNominal,
MR=0.0,
eps=self.epsNominal)
if isp > 0.0:
self.min_MR = 0.0
isp, cstr, self.Tc_at_min_MR = self.ispODEObj.get_IvacCstrTc(
Pc=self.PcNominal, MR=self.min_MR, eps=self.epsNominal)
if isp > 0.1 and self.Tc_at_min_MR > self.TC_LIMIT:
return
mr_top = self.Stoich_MR
mr_bot = 0.0
for i in range(40):
mr = (mr_top + mr_bot) / 2.0
isp, cstr, tc = self.ispODEObj.get_IvacCstrTc(Pc=self.PcNominal,
MR=mr,
eps=self.epsNominal)
if isp > 0.0 and tc > self.TC_LIMIT:
mr_top = mr
else:
mr_bot = mr
#print( 'Calculated Min MR = %g'%mr_top, ' Isp at Min MR =',self.ispODEObj.get_Isp( Pc=self.PcNominal, MR=mr_top, eps=eps) )
self.min_MR = mr_top
isp, cstr, self.Tc_at_min_MR = self.ispODEObj.get_IvacCstrTc(
Pc=self.PcNominal, MR=mr_top, eps=self.epsNominal)
def find_max_mr(self):
'''Find max mr where CEA Isp is Non-Zero AND Tc >= TC_LIMIT'''
isp = self.ispODEObj.get_Isp(Pc=self.PcNominal,
MR=self.MR_MAX,
eps=self.epsNominal)
if isp > 0.0:
self.max_MR = self.MR_MAX
isp, cstr, self.Tc_at_max_MR = self.ispODEObj.get_IvacCstrTc(
Pc=self.PcNominal, MR=self.max_MR, eps=self.epsNominal)
if isp > 0.0 and self.Tc_at_max_MR > self.TC_LIMIT:
return
mr_top = self.MR_MAX
mr_bot = self.Stoich_MR
for i in range(40):
mr = (mr_top + mr_bot) / 2.0
isp, cstr, tc = self.ispODEObj.get_IvacCstrTc(Pc=self.PcNominal,
MR=mr,
eps=self.epsNominal)
if isp > 0.0 and tc > self.TC_LIMIT:
mr_bot = mr
else:
mr_top = mr
#print( 'Calculated Max MR = %g'%mr_bot, ' Isp at Max MR =',self.ispODEObj.get_Isp( Pc=self.PcNominal, MR=mr_bot, eps=eps))
self.max_MR = mr_bot
isp, cstr, self.Tc_at_max_MR = self.ispODEObj.get_IvacCstrTc(
Pc=self.PcNominal, MR=mr_bot, eps=self.epsNominal)
def __str__(self):
return '''<%s/%s, Stoich_MR=%g, Min MR=%g, Max MR=%g, Tc Left=%g R, Tc Right=%g R>'''%\
(self.cea_oxName, self.cea_fuelName, self.Stoich_MR, self.min_MR, self.max_MR, self.Tc_at_min_MR, self.Tc_at_max_MR)
