def test_new_propellants(self):
card_str = """
oxid N2O4(L) N 2 O 4 wt%=96.5
h,cal=-4676.0 t(k)=298.15
oxid SIO2 SI 1 O 2 wt%=3,5
h,cal=-216000.0 t(k)=298.15 rho.g/cc=1.48
"""
add_new_oxidizer('GelN2O4', card_str)
# ==========
card_str = """
fuel CH6N2(L) C 1 H 6 N 2 wt%=60.00
h,cal=12900.0 t(k)=298.15 rho=.874
fuel AL 1 wt%=40.00
h,cal=0.0 t(k)=298.15 rho=.1
"""
add_new_fuel('MMH_AL', card_str)
C = CEA_Obj(oxName="GelN2O4", fuelName="MMH_AL", fac_CR=None)
IspODE = C.get_Isp(Pc=1850.0, MR=0.7, eps=40.0)
self.assertAlmostEqual(IspODE, 380.83236183365057, places=3)
# ==========
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", fac_CR=None)
IspODE = C.get_Isp(Pc=1850.0, eps=40.0)
self.assertAlmostEqual(IspODE, 189.9709005711723, places=3)
def test_win32_rocketcea_data_dir_spaces(self):
"""On Windows, use short path names when spaces in ROCKETCEA_DATA_DIR"""
if sys.platform == 'win32':
save_ROCKETCEA_DATA_DIR = get_rocketcea_data_dir()
try:
with tempfile.TemporaryDirectory() as tmpdirname:
print('created temporary directory', tmpdirname)
subdir = os.path.join(tmpdirname, 'cea w spaces')
os.mkdir(subdir)
print('subdir =', subdir)
print('os.path.exists(subdir) =', os.path.exists(subdir))
print()
set_rocketcea_data_dir(subdir)
C = CEA_Obj(oxName='LOX',
fuelName='LH2',
make_debug_prints=True)
Isp = C.get_Isp(Pc=100.0, MR=1.0, eps=40.0)
print(Isp)
finally:
# restore
set_rocketcea_data_dir(save_ROCKETCEA_DATA_DIR)
def test_get_Isp(self):
""" test call to get_Isp( Pc=100.0, MR=1.0, eps=40.0) """
C = CEA_Obj(oxName="LOX", fuelName="MMH", fac_CR=None)
IspODE = C.get_Isp(Pc=100.0, MR=1.0, eps=40.0)
self.assertAlmostEqual(IspODE, 351.7388076713265, places=3)
del C
def test_get_Isp(self):
""" test call to get_Isp( Pc=100.0, MR=1.0, eps=40.0) """
C = CEA_Obj(oxName="LOX", fuelName="MMH", fac_CR=2.5)
IspODE = C.get_Isp(Pc=100.0, MR=1.0, eps=40.0)
self.assertAlmostEqual(IspODE, 351.7235908873327, places=3)
del C
def test_use_Mpa_as_input_Pc(self):
"""test use Mpa as input Pc"""
C = CEA_Obj( oxName='LOX', fuelName='LH2', fac_CR=None)
CwU = CEA_Obj_w_units( oxName='LOX', fuelName='LH2', pressure_units='MPa', fac_CR=None)
a = C.get_Isp(Pc=1000.0, MR=6.0, eps=40.0)
b = CwU.get_Isp(Pc=1000.0/145.037738, MR=6.0, eps=40.0)
self.assertAlmostEqual(a, b, delta=0.01)
def test_froz_get_Isp(self):
""" test call to get_Isp( Pc=100.0, MR=1.0, eps=40.0) """
C = CEA_Obj(oxName="LOX", fuelName="MMH", fac_CR=None)
IspODE = C.get_Isp(Pc=100.0,
MR=1.0,
eps=40.0,
frozen=1,
frozenAtThroat=0)
self.assertAlmostEqual(IspODE, 335.7939948810785, places=3)
del C
from rocketcea.cea_obj import CEA_Obj
C = CEA_Obj(oxName="LOX", fuelName="H2", useFastLookup=0)
Pc = 500.
MR = 6.0
for eps in [2., 5., 7., 10., 20., 50.]:
IspVac = C.get_Isp(Pc=Pc, MR=MR, eps=eps)
IspAmb, mode = C.estimate_Ambient_Isp(Pc=Pc, MR=MR, eps=eps, Pamb=14.7)
print('Pc=%4i eps=%3i IspAmb/IspVac= %6.2f/%6.2f Mode= %s' %
(int(Pc), int(eps), IspAmb, IspVac, mode))
'CH4': 0.444,
'C2H6_167': 0.8343,
'N2H4': 1.0037,
'CLF5': 1.776,
'MMH': 0.8702,
'N2O4': 1.433,
'NH3': 0.405
}
for oxName,fuelName in [('OF2','B2H6'),('OF2','C3H8'),('OF2','CH4'),\
('OF2','C2H6_167'),('OF2','N2H4'),\
('CLF5','N2H4'),('N2O4','MMH')]:
ispObj = CEA_Obj(oxName=oxName, fuelName=fuelName)
ispL = [ispObj.get_Isp(Pc=Pc, MR=MR, eps=eps) for MR in mrL]
sgOx = sgD[oxName]
sgFuel = sgD[fuelName]
rhoIspL = []
for MR, Isp in zip(mrL, ispL):
sgBulk = (MR + 1.0) / (MR / sgOx + 1. / sgFuel)
rhoIspL.append(Isp * sgBulk)
rhoIspLL.append([max(rhoIspL), '%s/%s' % (oxName, fuelName), rhoIspL])
rhoIspLL.sort(reverse=True) # sort in-place from high to low
for maxIsp, name, rhoIspL in rhoIspLL:
plot(mrL, rhoIspL, label=name, linewidth=2)
def __init__(self,
figsize=(10, 8),
dpi=70,
Pc=500.,
eps=20.,
nsteps_sg=100,
nsteps_isp=100,
legend_loc='best',
show_mr_on_plot=False,
show_frozen_isp_on_plot=False,
bipropL=None,
monopropL=None,
spec_gravD=None):
if bipropL is None:
bipropL = [('LOX', 'LH2'), ('N2O4', 'MMH'), ('LOX', 'RP1'),
('FLOX80', 'CH4'), ('IRFNA', 'MHF3'), ('LOX', 'CH4'),
('F2', 'H2'), ('F2', 'N2H4'), ('CLF5', 'N2H4'),
('N2F4', 'N2H4')]
self.figsize = figsize
self.dpi = dpi
self.Pc = Pc
self.eps = eps
self.headline = 'Pc=%g psia, Area Ratio=%g:1' % (self.Pc, self.eps)
self.nsteps_sg = nsteps_sg # controls grid on plot for interplating stage properties
self.nsteps_isp = nsteps_isp
# 'best', 'upper right', 'right', 'center', 'lower center', 'center right', etc.
self.legend_loc = legend_loc
self.show_mr_on_plot = show_mr_on_plot
self.show_frozen_isp_on_plot = show_frozen_isp_on_plot
self.bipropL = bipropL
if monopropL is None:
monopropL = []
self.monopropL = monopropL
self.monoprop_sgIspD = {} #index:name, value:(sg, Isp)
self.fig = plt.figure(figsize=figsize, dpi=dpi) # figsize=(NxM) inches
self.added_props_to_plot = False
if spec_gravD is not None:
for key, val in spec_gravD.items():
add_prop_sg(name, val)
self.mr_objL = []
self.isp_min = 9999.0 # initialize extents of plot
self.isp_max = 0.0
self.sg_min = 9999.0
self.sg_max = 0.0
for (oxName, fuelName) in bipropL:
if not got_sg(oxName):
raise Exception('%s Specific Gravity Missing...\n'%oxName +\
' add to spec_gravD["%s"]'%oxName)
if not got_sg(fuelName):
raise Exception('%s Specific Gravity Missing...\n'%fuelName +\
' add to spec_gravD["%s"]'%fuelName)
tobj = MR_Temperature_Limits(oxName=oxName,
fuelName=fuelName,
TC_LIMIT=1500.0,
PcNominal=Pc,
epsNominal=eps,
MR_MIN=0.0,
MR_MAX=200.0)
self.mr_objL.append(MR_Peak_At_EpsPc(tobj, pc=Pc, eps=eps))
add_sg_isp_to_mr_obj(self.mr_objL[-1])
if show_frozen_isp_on_plot:
add_frozen_isp_to_mr_obj(self.mr_objL[-1], Pc=Pc, eps=eps)
self.isp_min = min(self.isp_min, self.mr_objL[-1].isp_min)
self.isp_max = max(self.isp_max, self.mr_objL[-1].isp_max)
self.sg_min = min(self.sg_min, self.mr_objL[-1].sg_min)
self.sg_max = max(self.sg_max, self.mr_objL[-1].sg_max)
for propName in self.monopropL:
sg = get_sg(propName)
if sg is not None:
self.sg_min = min(self.sg_min, sg)
self.sg_max = max(self.sg_max, sg)
ispObj = CEA_Obj(propName=propName)
Isp = ispObj.get_Isp(Pc=Pc, eps=eps)
self.isp_min = min(self.isp_min, Isp)
self.isp_max = max(self.isp_max, Isp)
self.monoprop_sgIspD[propName] = (sg, Isp)
self.rhobRange = self.sg_max - self.sg_min
self.ispRange = self.isp_max - self.isp_min
from rocketcea.cea_obj import CEA_Obj, ROCKETCEA_DATA_DIR
print('ROCKETCEA_DATA_DIR =', ROCKETCEA_DATA_DIR)
C = CEA_Obj(oxName='LOX', fuelName='LH2', makeOutput=1, make_debug_prints=True)
Isp = C.get_Isp(Pc=100.0, MR=1.0, eps=40.0)
print(Isp)
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
import standard_fluid_config as std
pcM = [50e5]
ethanol90 = rocketcea.blends.newFuelBlend(
fuelL=['C2H5OH', 'H2O'], fuelPcentL=[80, 20]) # new fule blend for CEA
ispObj = CEA_Obj(propName='', oxName='LOX', fuelName=ethanol90)
for Pc in pcM:
ispArr = []
TArr = []
MR = 0.6
mrArr = []
while MR < 2:
ispArr.append(
ispObj.get_Isp(Pc=Pc * 0.000145038, MR=MR,
eps=std.expansion_ratio))
TArr.append(ispObj.get_Tcomb(Pc=Pc * 0.000145038, MR=MR) * 0.555556)
mrArr.append(MR)
MR += 0.001
pl.plot(mrArr, ispArr, label='Pc=%g Pa' % Pc)
pl.legend(loc='best')
pl.grid(True)
pl.title(ispObj.desc)
pl.xlabel('Mixture Ratio [-]')
pl.ylabel('Isp [s]')
pl.show()
pl.plot(mrArr, TArr, label='Pc=%g Pa' % Pc)
pl.legend(loc='best')
pl.grid(True)
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)
from rocketcea.cea_obj import CEA_Obj
from pylab import *
C = CEA_Obj(oxName='LOX', fuelName='LH2')
for mr in range(2, 9):
print(mr, C.get_Isp(Pc=100.0, MR=mr, eps=40.0))
Pc = 500.0
eps = 15.0
mrMin = 1.0
mrStep = 0.05
mrMax = 3.0
mrL = [mrMin + i * mrStep for i in range(int((mrMax - mrMin) / mrStep))]
ispLL = [] # a list of lists of Isp data
for oxName, fuelName in [('LOX', 'RP1'), ('LOX', 'RP1'), ('LOX', 'RP1'),
('LOX', 'RP1'), ('LOX', 'RP1')]:
ispObj = CEA_Obj(oxName=oxName, fuelName=fuelName)
ispL = [ispObj.get_Isp(Pc=Pc, MR=MR, eps=eps) for MR in mrL]
ispLL.append([max(ispL), '%s/%s' % (oxName, fuelName), ispL])
ispLL.sort(reverse=True) # sort in-place from high to low
for maxIsp, name, ispL in ispLL:
plot(mrL, ispL, label=name, linewidth=2)
legend(loc='best')
grid(True)
