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_mole_fraction_species_conc_w_fac(self):
"""test mole fraction species concentration with finite area combustor"""
C = CEA_Obj(oxName='LOX', fuelName='LH2', fac_CR=2.5)
molWtD, massFracD = C.get_SpeciesMoleFractions(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=0,
frozenAtThroat=0)
self.assertEqual(len(massFracD), 8)
self.assertEqual(len(molWtD), 8)
s = ' '.join(['%7.5f' % mf for mf in massFracD["H2O"]])
self.assertEqual(s, "0.66590 0.66670 0.68697 0.75598")
molWtD, massFracD = C.get_SpeciesMoleFractions(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1,
frozenAtThroat=0)
self.assertEqual(len(massFracD), 8)
self.assertEqual(len(molWtD), 8)
s = ' '.join(['%7.5f' % mf for mf in massFracD["H2O"]])
self.assertEqual(s, "0.66590 0.66590 0.66590 0.66590")
molWtD, massFracD = C.get_SpeciesMoleFractions(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1,
frozenAtThroat=1)
self.assertEqual(len(massFracD), 8)
self.assertEqual(len(molWtD), 8)
s = ' '.join(['%7.5f' % mf for mf in massFracD["H2O"]])
self.assertEqual(s, "0.66590 0.66670 0.68697 0.68697")
del C
def test_mole_fraction_species_concentration(self):
"""test mole fraction species concentration"""
C = CEA_Obj(oxName='LOX', fuelName='LH2')
molWtD, massFracD = C.get_SpeciesMoleFractions(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=0,
frozenAtThroat=0)
self.assertEqual(len(massFracD), 8)
self.assertEqual(len(molWtD), 8)
s = ' '.join(['%7.5f' % mf for mf in massFracD["H2O"]])
self.assertEqual(s, "0.66590 0.66590 0.68751 0.75598")
molWtD, massFracD = C.get_SpeciesMoleFractions(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1,
frozenAtThroat=0)
self.assertEqual(len(massFracD), 8)
self.assertEqual(len(molWtD), 8)
s = ' '.join(['%7.5f' % mf for mf in massFracD["H2O"]])
self.assertEqual(s, "0.66590 0.66590 0.66590 0.66590")
molWtD, massFracD = C.get_SpeciesMoleFractions(Pc=1000.0,
MR=6.0,
eps=40.0,
frozen=1,
frozenAtThroat=1)
self.assertEqual(len(massFracD), 8)
self.assertEqual(len(molWtD), 8)
s = ' '.join(['%7.5f' % mf for mf in massFracD["H2O"]])
self.assertEqual(s, "0.66590 0.66590 0.68751 0.68751")
del C
def engine_adiabatic(P_cc, P_e, n_ps, T_cc, F_th, eta_nz, ox, fuel, ofr, r_cc):
step, P, T, rho, kappa, h, u, c, M, r = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
cea = CEA_Obj(fuelName=fuel, oxName=ox)
mix_cc = prune_cc_products(
cea.get_SpeciesMoleFractions(Pc=psi(P_cc), MR=ofr)[1])
eng = np.zeros((10, n_ps + 1))
eng[step, :] = np.arange(0, n_ps + 1)
eng[P, :] = P_cc - ((P_cc - P_e) / n_ps) * eng[0, :]
eng[T, 0] = cea.get_Temperatures(Pc=psi(P_cc), MR=ofr)[0] * (5 / 9)
#print(eng[T,0])
#print(psi(eng[P,0]))
eng[rho, 0] = thermo.get_rho(eng[P, 0], eng[T, 0], mix_cc)
eng[kappa, 0] = thermo.get_kappa(eng[P, 0], eng[T, 0], mix_cc)
eng[h, 0] = thermo.mass_mixer(mix_cc, eng[P, 0], 'P', eng[T, 0], 'T', 'H')
eng[u, 0] = 0
eng[c, 0] = thermo.get_speed_of_sound(eng[P, 0], eng[T, 0], mix_cc)
eng[M, 0] = eng[u, 0] / eng[c, 0]
eng[r, 0] = r_cc
for i in tqdm(eng[step, :]):
i = int(i)
if (i != 0):
eng[T, i] = thermo.isentrop_temp_press(eng[kappa,
i - 1], eng[T, i - 1],
eng[P, i - 1], eng[P, i])
eng[rho, i] = thermo.get_rho(eng[P, i], eng[T, i], mix_cc)
eng[kappa, i] = thermo.get_kappa(eng[P, i], eng[T, i], mix_cc)
eng[h, i] = thermo.mass_mixer(mix_cc, eng[P, i], 'P', eng[T, i],
'T', 'H')
eng[u,
i] = ((eng[h, i - 1] - eng[h, i]) * 2 + eng[u, i - 1]**2)**0.5
eng[c, i] = thermo.get_speed_of_sound(eng[P, i], eng[T, i], mix_cc)
eng[M, i] = eng[u, i] / eng[c, i]
m_dot = F_th / eng[u, -1]
#print(mix_cc)
eng[u, 0] = m_dot / (eng[rho, 0] * eng[r, 0]**2 * math.pi)
for i in eng[step, :]:
i = int(i)
if (i != 0):
eng[u,
i] = ((eng[h, i - 1] - eng[h, i]) * 2 + eng[u, i - 1]**2)**0.5
eng[M, i] = eng[u, i] / eng[c, i]
eng[r, :] = np.vectorize(lambda u, rho:
(m_dot / (math.pi * u * rho))**0.5)(eng[u, :],
eng[rho, :])
print(m_dot)
return eng
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
from rocketcea.cea_obj import CEA_Obj
ispObj = CEA_Obj( oxName='LOX', fuelName='LH2')
for frozen, frozenAtThroat in [(0,0), (1,0), (1,1)]:
molWtD, moleFracD = ispObj.get_SpeciesMoleFractions( Pc=1000.0, MR=6.0, eps=40.0,
frozen=frozen, frozenAtThroat=frozenAtThroat )
print(' ROCKETCEA MOLE FRACTIONS (frozen=%i, frozenAtThroat=%i)'%(frozen, frozenAtThroat) )
for species, mfL in moleFracD.items():
s = ' '.join( [ '%7.5f'%mf for mf in mfL ] )
print( ' %-15s '%species, s, ' MW=%g'%molWtD[species] )
print('='*55)
class AdiabaticEngine:
step, P, T, rho, kappa, h, u, c, M, r = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
def __init__(self,
fuel,
oxidizer,
P_cc,
P_e,
F_t,
ofr,
r_cc,
steps,
eta_n=1,
stepfactor=10):
self.fuel = fuel
self.oxidizer = oxidizer
self.P_cc = P_cc
self.P_e = P_e
self.F_t = F_t
self.ofr = ofr
self.r_cc = r_cc
self.steps = steps
self.eta_n = eta_n
self.p_steps = stepfactor * steps
self.steps = steps
self.p_data = np.zeros((10, self.p_steps + 1))
def __repr__(self):
pass
def __str__(self):
pass
def generate(self, disable_tqdm=False):
self.cea = CEA_Obj(fuelName=self.fuel, oxName=self.oxidizer)
self.mix_cc = self.prune_combustion_products(
self.cea.get_SpeciesMoleFractions(Pc=psi(self.P_cc),
MR=self.ofr)[1])
self.p_data[self.step, :] = np.arange(0, self.p_steps + 1)
self.p_data[self.P, :] = self.P_cc - (
(self.P_cc - self.P_e) / self.p_steps) * self.p_data[self.step, :]
self.p_data[self.T,
0] = self.cea.get_Temperatures(Pc=psi(self.P_cc),
MR=self.ofr)[0] * (5 / 9)
self.p_data[self.rho, 0] = thermo.get_rho(self.p_data[self.P, 0],
self.p_data[self.T,
0], self.mix_cc)
self.p_data[self.kappa,
0] = thermo.get_kappa(self.p_data[self.P, 0],
self.p_data[self.T, 0], self.mix_cc)
self.p_data[self.h,
0] = thermo.mass_mixer(self.mix_cc, self.p_data[self.P, 0],
'P', self.p_data[self.T,
0], 'T', 'H')
self.p_data[self.u, 0] = 0
self.p_data[self.c,
0] = thermo.get_speed_of_sound(self.p_data[self.P, 0],
self.p_data[self.T,
0], self.mix_cc)
self.p_data[self.M,
0] = self.p_data[self.u, 0] / self.p_data[self.c, 0]
self.p_data[self.r, 0] = self.r_cc
for i in tqdm(self.p_data[self.step, 1:],
desc="Generating slices",
disable=disable_tqdm):
i = int(i)
self.p_data[1:, i] = self.__next_step(self.p_data[:, i - 1],
self.p_data[self.P, i])
self.m_dot = self.F_t / self.p_data[self.u, -1]
self.p_data[self.u,
0] = self.m_dot / (self.p_data[self.rho, 0] *
self.p_data[self.r, 0]**2 * math.pi)
for i in tqdm(self.p_data[self.step, 1:],
desc="Calculating velocities",
disable=disable_tqdm):
i = int(i)
self.p_data[self.u, i] = (
(self.p_data[self.h, i - 1] - self.p_data[self.h, i]) * 2 +
self.p_data[self.u, i - 1]**2)**0.5
self.p_data[self.M,
i] = self.p_data[self.u, i] / self.p_data[self.c, i]
self.p_data[self.r, :] = np.vectorize(
lambda u, rho: (self.m_dot / (math.pi * u * rho))**0.5)(
self.p_data[self.u, :], self.p_data[self.rho, :])
delta = 1000
self.t_step = 0
for i in self.p_data[self.step, :]:
i = int(i)
if abs(self.p_data[self.M, i] - 1) < delta:
delta = abs(self.p_data[self.M, i] - 1)
self.t_step = i
print(self.t_step)
print(delta)
self.r_e = self.p_data[self.r, -1]
self.r_t = self.p_data[self.r, self.t_step]
def __next_step(self, prev, P_now):
T_now = thermo.isentrop_temp_press(prev[self.kappa], prev[self.T],
prev[self.P], P_now)
rho_now = thermo.get_rho(P_now, T_now, self.mix_cc)
kappa_now = thermo.get_kappa(P_now, T_now, self.mix_cc)
h_now = thermo.mass_mixer(self.mix_cc, P_now, 'P', T_now, 'T', 'H')
u_now = ((prev[self.h] - h_now) * 2 + prev[self.u]**2)**0.5
c_now = thermo.get_speed_of_sound(P_now, T_now, self.mix_cc)
M_now = u_now / c_now
return np.array(
[P_now, T_now, rho_now, kappa_now, h_now, u_now, c_now, M_now, 0])
def prune_combustion_products(self,
cea_dict,
cutoff=0.01,
exclude=["*NO", "*O", "*OH", "*H"],
pos=1):
cp_dict = {}
total = 0
for key in cea_dict:
if (cea_dict[key][pos] > cutoff) and not (key in exclude):
cp_dict[key.strip('*')] = cea_dict[key][pos]
total += cea_dict[key][pos]
for key in cp_dict:
cp_dict[key] = cp_dict[key] / total
return cp_dict
def matcher(self, nozzle):
pass
def quickset(self):
pass
from rocketcea.cea_obj import CEA_Obj
C = CEA_Obj(oxName='GOX', fuelName='GH2')
Pc = 40.0
eps = 5.0
MR = 5.0
molWtD, moleFracD = C.get_SpeciesMoleFractions(Pc=Pc, MR=MR, eps=eps)
print(' ROCKETCEA MOLE FRACTIONS')
for species, mfL in moleFracD.items():
s = ' '.join(['%7.5f' % mf for mf in mfL])
print(' %-15s ' % species, s, ' MW=%g' % molWtD[species])
print(""" CEA OUTPUT MOLE FRACTIONS
*H 0.07147 0.06044 0.00962
HO2 0.00001 0.00000 0.00000
*H2 0.34261 0.34471 0.36428
H2O 0.53522 0.55597 0.62354
*O 0.00497 0.00332 0.00004
*OH 0.04266 0.03344 0.00249
*O2 0.00306 0.00212 0.00003
""")
