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#!/usr/bin/env python 

# -*- coding: ascii -*- 

 

r""" 

RocketCEA wraps the NASA FORTRAN CEA code and provides some useful tools. 

 

RocketCEA makes direct calls to the FORTRAN CEA code in "rocket" mode to calculate 

Isp, Cstar, Tcham etc. and provides tools to help determine useful 

mixture ratio range, optimum MR and more. 

 

See the NASA CEA code at: `<https://www.grc.nasa.gov/WWW/CEAWeb/>`_ 

 

RocketCEA 

Copyright (C) 2005-2018 Applied Python 

 

This program is free software: you can redistribute it and/or modify 

it under the terms of the GNU General Public License as published by 

the Free Software Foundation, either version 3 of the License, or 

(at your option) any later version. 

 

This program is distributed in the hope that it will be useful, 

but WITHOUT ANY WARRANTY; without even the implied warranty of 

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

GNU General Public License for more details. 

 

You should have received a copy of the GNU General Public License 

along with this program. If not, see <http://www.gnu.org/licenses/>. 

 

----------------------- 

 

""" 

 

import os, sys 

here = os.path.abspath(os.path.dirname(__file__)) 

import shutil 

 

USER_HOME_DIR = os.path.dirname( os.path.expanduser('~/') ) 

ROCKETCEA_DATA_DIR = os.path.join( USER_HOME_DIR, 'RocketCEA' ) 

 

# # python >=3.8 needs to be given permission to import DLL files. 

from rocketcea.find_mingw_lib import add_mingw_lib 

add_mingw_lib() 

 

# for multi-file projects see LICENSE file for authorship info 

# for single file projects, insert following information 

__author__ = 'Charlie Taylor' 

__copyright__ = 'Copyright (c) 2018 Charlie Taylor' 

__license__ = 'GPL-3' 

exec( open(os.path.join( here,'_version.py' )).read() ) # creates local __version__ variable 

__email__ = "cet@appliedpython.com" 

__status__ = "4 - Beta" # "3 - Alpha", "4 - Beta", "5 - Production/Stable" 

 

from rocketcea.input_cards import oxCards, fuelCards, propCards 

from rocketcea.blends import newFuelBlend, newOxBlend, renamePropIfNewHfOrTrefInName 

from rocketcea.blends import isAPeroxide_Blend, isAnMMH_N2H4_Blend, isMON_Ox_Blend, isFLOX_Ox_Blend, is_HYD_Ammonia_Blend 

from rocketcea.blends import addPeroxideBlend, addMON_Blend, addFLOX_Blend, addMMH_N2H4_Blend, addHYD_AmmoniaBlend 

 

try: 

import rocketcea.py_cea as py_cea 

except: 

# automodule doc builds fail on ReadTheDocs w/o some error handling. 

if os.environ.get('READTHEDOCS',False): 

print('Allowing py_cea import to fail on READTHEDOCS.') 

py_cea = None 

else: 

# go ahead and raise the error. 

import rocketcea.py_cea as py_cea 

 

 

from rocketcea.separated_Cf import ambientCf, sepNozzleCf 

# 

# gravitational conversion factor 

GC = 32.174 

 

_last_called = None # remember the last object to read the datafile 

_NLines_Max_ever = 0 # make sure to overwrite any lines from previous calls 

 

# hold CEA_Cache objects by propellant name 

_CacheObjDict = {} 

def getCacheDict(): 

"""Returns internal cache of previously called calculations.""" 

return _CacheObjDict 

 

def set_py_cea_line(N, line): 

'''make sure that trailing blanks are on added lines''' 

ln = line + " " 

py_cea.setinpline(N, ln) 

#print( '"'+ln[:77]+'"' ) 

 

 

def add_new_card( name, card_str, propD ): 

""":: 

 

#: Add or Replace a propellant. 

#: name = string name (e.g. oxName, fuelName or propName) 

#: card_str = a single multiline string containing CEA input card for new propellant 

#: propD = dictionary to receive new propellant (e.g. oxCards, fuelCards or propCards) 

""" 

 

sL = card_str.split('\n') 

cardL = [] 

for s in sL: 

s = s.strip() 

if s: 

cardL.append( ' ' + s + ' ' ) # make sure there are spaces around each line entry 

propD[ name ] = cardL 

 

 

def add_new_fuel( name, card_str ): 

"""Add a new Fuel Card""" 

add_new_card( name, card_str, fuelCards ) 

 

def add_new_oxidizer( name, card_str ): 

"""Add a new Oxidizer Card""" 

add_new_card( name, card_str, oxCards ) 

 

def add_new_propellant( name, card_str ): 

"""Add a new Propellant Card""" 

add_new_card( name, card_str, propCards ) 

 

 

_PrintCountDict = {} 

 

 

class CEA_Cache(object): 

def __init__(self, maxCache=10000, propName=None): 

"""Create the cache object that saves previous calculations in RAM to speed repetitive calls.""" 

 

self.maxCache = maxCache 

self.propName = propName 

self.ispDict = {} 

self.cstarDict = {} 

self.tcDict = {} 

 

# keep track of size, assume faster than a len( xxDict ) call 

self.Nisp = 0 

self.Ncstar = 0 

self.Ntc = 0 

 

def setIsp(self, desc='', isp=0.0): 

# do not check for existence, assume usage logic handles that 

if self.Nisp < self.maxCache: 

self.Nisp += 1 

#print( 'in setIsp, desc=',desc,' isp=',isp ) 

self.ispDict[desc] = isp 

 

def setCstar(self, desc='', cstar=0.0): 

# do not check for existence, assume usage logic handles that 

if self.Ncstar < self.maxCache: 

self.Ncstar += 1 

self.cstarDict[desc] = cstar 

 

def setTcK(self, desc='', tc=0.0): 

# do not check for existence, assume usage logic handles that 

if self.Ntc < self.maxCache: 

self.Ntc += 1 

self.tcDict[desc] = tc 

 

def getIsp(self, desc=''): 

try: 

return self.ispDict[desc] 

except: 

return None 

 

def getCstar(self, desc=''): 

try: 

return self.cstarDict[desc] 

except: 

return None 

 

def getTcK(self, desc=''): 

try: 

return self.tcDict[desc] 

except: 

return None 

 

class CEA_Obj(object): 

""" 

RocketCEA wraps the NASA FORTRAN CEA code to calculate Isp, cstar, and Tcomb 

""" 

 

def __init__(self, propName='', oxName='', fuelName='', fac_CR=None, 

useFastLookup=0, # depricated 

makeOutput=0, make_debug_prints=False): 

""" 

#: Create the base CEA wrapper object. 

#: Fast Lookup is depricated. 

#: fac_CR = Contraction Ratio of finite area combustor (None=infinite) 

#: if make_debug_prints is True, print debugging info to terminal. 

""" 

 

self.makeOutput = makeOutput # makes "f.out" 

self.make_debug_prints = make_debug_prints 

 

if fac_CR is not None: 

self.fac_CR = float( fac_CR ) 

#print('Creating CEA_Obj with finite area combustor CR = ', self.fac_CR) 

else: 

self.fac_CR = None 

 

oxName = renamePropIfNewHfOrTrefInName( oxCards, oxName ) 

fuelName = renamePropIfNewHfOrTrefInName( fuelCards, fuelName ) 

propName = renamePropIfNewHfOrTrefInName( propCards, propName ) 

 

 

oxName = oxName.replace('(g)', '(G)') 

fuelName = fuelName.replace('(g)', '(G)') 

propName = propName.replace('(g)', '(G)') 

 

# do NOT allow "-" or "+" as part of the name 

oxName = oxName.replace('-', '_') 

fuelName = fuelName.replace('-', '_') 

propName = propName.replace('-', '_') 

 

oxName = oxName.replace('+', '_') 

fuelName = fuelName.replace('+', '_') 

propName = propName.replace('+', '_') 

 

if oxName[-3:]=='(G)': 

oxName = 'G' + oxName[:-3] 

if self.make_debug_prints: 

print('Ox name changed to',oxName) 

if fuelName[-3:]=='(G)': 

fuelName = 'G' + fuelName[:-3] 

if self.make_debug_prints: 

print('Fuel name changed to',fuelName) 

if propName[-3:]=='(G)': 

propName = 'G' + propName[:-3] 

if self.make_debug_prints: 

print('Propellant name changed to',propName) 

 

# may want to interpolate tables of CEA runs for speed 

if useFastLookup: 

print('WARNING... useFastLookup is no longer supported.') 

self.useFastLookup = 0 

 

self.readDatafileOnce = 0 

 

#check for propellant (mono or solid) vs. fuel and ox 

self.cea_deck = ["reac"] 

self.desc = '' 

self.useMR = 1 

self.propName = propName 

if len(propName)>0: # can be in propCards, fuelCards, or oxCards 

if propName in propCards: 

self.cea_deck.append( propCards[ propName ] ) 

self.desc += ' ' + propName 

 

elif is_HYD_Ammonia_Blend( propName ): #HYD40 will be caught above 

addHYD_AmmoniaBlend( propName, self.cea_deck ) # e.g. HYD30, HYD25.5 

self.desc += propName 

 

elif propName in fuelCards: 

tempList = fuelCards[ propName ] 

if type(tempList) == type(''): 

tempList = [tempList] 

 

propList = [] 

for p in tempList: 

propList.append( p.replace(' fuel ',' name ' ) ) 

 

self.cea_deck.append( propList ) 

self.desc += ' ' + propName 

if self.make_debug_prints: 

print("fuel Cards converted into prop Cards") 

for card in self.cea_deck: 

if type(card) == type(''): 

print(card) 

else: 

for c in card: 

print(c) 

elif propName in oxCards: 

tempList = oxCards[ propName ] 

if type(tempList) == type(''): 

tempList = [tempList] 

 

propList = [] 

for p in tempList: 

propList.append( p.replace(' oxid ',' name ' ) ) 

 

self.cea_deck.append( propList ) 

self.desc += ' ' + propName 

if self.make_debug_prints: 

print("ox Cards converted into prop Cards") 

for card in self.cea_deck: 

if type(card) == type(''): 

print(card) 

else: 

for c in card: 

print(c) 

else: 

print('ERROR... bad propellant name (%s) in cea_obj.py'%propName) 

 

self.useMR = 0 

 

#check for fuel 

self.fuelName = fuelName 

if len(fuelName)>0: 

if fuelName in fuelCards: 

self.cea_deck.append( fuelCards[ fuelName ] ) 

self.desc += fuelName 

 

elif isAnMMH_N2H4_Blend( fuelName ): #M20 will be caught above 

addMMH_N2H4_Blend( fuelName, self.cea_deck ) # e.g. M10, M15, M23.789 

self.desc += fuelName 

 

else: 

print('ERROR... bad fuel name (%s) in cea_obj.py'%fuelName) 

raise Exception('ERROR... bad fuel name (%s) in cea_obj.py'%fuelName) 

 

#check for oxidizer 

self.oxName = oxName 

if len(oxName)>0: 

if oxName in oxCards: 

self.cea_deck.append( oxCards[ oxName ] ) 

self.desc = oxName + ' / ' + self.desc 

 

elif isAPeroxide_Blend( oxName ): 

addPeroxideBlend( oxName, self.cea_deck ) 

self.desc = oxName + ' / ' + self.desc 

 

elif isMON_Ox_Blend( oxName ): 

addMON_Blend(oxName, self.cea_deck) 

self.desc = oxName + ' / ' + self.desc 

 

elif isFLOX_Ox_Blend( oxName ): 

addFLOX_Blend( oxName, self.cea_deck ) 

self.desc = oxName + ' / ' + self.desc 

 

else: 

print('ERROR... bad oxidizer name (%s) in cea_obj.py'%oxName) 

raise Exception('ERROR... bad oxidizer name (%s) in cea_obj.py'%oxName) 

 

if self.fac_CR is not None: 

self.desc += ' CR=%g'%self.fac_CR 

 

#thisPath = py_cea.__file__ 

#print('py_cea.__file__ =' + py_cea.__file__) 

#print('here =' + here) 

#dataPath = os.path.dirname( thisPath ) 

#sp = dataPath.split('\\') 

#dataPath = '/'.join( sp ) + '/ ' # be sure to leave extra space 

#self.pathPrefix = here + os.sep + ' ' # be sure to leave extra space # dataPath 

 

self.pathPrefix = ROCKETCEA_DATA_DIR + os.sep + ' ' # be sure to leave os.sep + extra space # dataPath 

 

if not os.path.exists( ROCKETCEA_DATA_DIR ): 

os.mkdir( ROCKETCEA_DATA_DIR, 0o777 ) 

 

def maybe_copy( fname ): 

if not os.path.exists( os.path.join(ROCKETCEA_DATA_DIR, fname) ): 

if os.path.exists( os.path.join(here, fname) ): 

shutil.copyfile( os.path.join(here, fname), os.path.join(ROCKETCEA_DATA_DIR, fname) ) 

 

maybe_copy( 'f.inp' ) 

maybe_copy( 'f.out' ) 

maybe_copy( 'temp.dat' ) 

maybe_copy( 'thermo.lib' ) 

maybe_copy( 'trans.lib' ) 

 

#shutil.copyfile( os.path.join(here, 'f.inp'), os.path.join(ROCKETCEA_DATA_DIR, 'f.inp') ) 

#shutil.copyfile( os.path.join(here, 'f.out'), os.path.join(ROCKETCEA_DATA_DIR, 'f.out') ) 

#shutil.copyfile( os.path.join(here, 'temp.dat'), os.path.join(ROCKETCEA_DATA_DIR, 'temp.dat') ) 

#shutil.copyfile( os.path.join(here, 'thermo.lib'), os.path.join(ROCKETCEA_DATA_DIR, 'thermo.lib') ) 

#shutil.copyfile( os.path.join(here, 'trans.lib'), os.path.join(ROCKETCEA_DATA_DIR, 'trans.lib') ) 

 

#self.pathPrefix = self.pathPrefix.replace('\\','/') 

print( "self.pathPrefix -->",self.pathPrefix ) 

 

# make a cache object for this propellant combo if it does not already exist 

try: 

cacheObj = _CacheObjDict[ self.desc ] 

except: 

_CacheObjDict[ self.desc ] = CEA_Cache(maxCache=10000, propName=self.desc ) 

 

 

 

def setupCards(self, Pc=100.0, MR=1.0, eps=40.0, subar=None, PcOvPe=None, frozen=0, 

ERphi=None, ERr=None, frozenAtThroat=0, short_output=0, 

show_transport=0, pc_units='psia', output='calories', 

show_mass_frac=False): 

''' 

Set up card deck and call CEA FORTRAN code.:: 

 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: if PcOvPe has a value, use it instead of eps to run case 

#: ERphi = Equivalence ratios in terms of fuel-to-oxidant weight ratios. 

#: ERr = Chemical equivalence ratios in terms of valences. 

#: pc_units = 'psia', 'bar', 'atm', 'mmh'(mm of mercury) 

#: frozen flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

''' 

 

global _last_called, _NLines_Max_ever 

 

N = 1 

for line in self.cea_deck: 

if type(line) == type("str"): 

set_py_cea_line(N, line) 

N += 1 

else: # might be a list of strings 

for ln in line: 

set_py_cea_line(N, ln) 

N += 1 

 

set_py_cea_line(N," ") 

N += 1 

 

#if self.desc==self.oxName + ' / ' + self.fuelName: 

# temp_prop_case = self.oxName + '_/_' + self.fuelName 

#else: 

# temp_prop_case = self.desc 

temp_prop_case='RocketCEA' 

 

set_py_cea_line(N,"prob case="+temp_prop_case+", ") 

#set_py_cea_line(N,"prob case="+self.desc+" ") 

 

 

N += 1 

#print( "prob case="+self.desc+" " ) 

 

if frozen: 

if frozenAtThroat: 

if self.fac_CR is not None: 

eqfrStr = 'frozen nfz=3 ' # nfz=3 for fac run 

else: 

eqfrStr = 'frozen nfz=2 ' # nfz=2 is throat, nfz=1 is chamber 

else: 

eqfrStr = 'frozen nfz=1 ' # nfz=1 is chamber 

else: 

eqfrStr = 'equilibrium' 

 

# ======================== make input strings for single or multiple values ================== 

# i.e. get_full_cea_output may input lists for eps, PcOvPe, Pc, MR, or subar 

 

def make_inp_str( param=' supar=', val=1.0 ): 

"""allow number, list or None.  

Return empty string for error or None.""" 

if val is None: 

return '' 

try: 

rtn_str = param + '%f, '%val #e.g. " supar=%f, "%eps 

return rtn_str 

except: 

pass 

try: 

# e.g. " supar=%s, "% ','.join( ['%g'%v for v in eps] ) 

rtn_str = param + '%s, '%','.join( ['%g'%v for v in val] ) 

except: 

rtn_str = '' 

 

return rtn_str 

 

# ------------ Eps String ------------ 

eps_str = make_inp_str( " supar=", eps ) 

 

# ------------ Pc String ------------- 

pc_str = make_inp_str( " p,%s="%pc_units, Pc ) 

 

# ------------ Subsonic Area Ration String ---------- 

subar_str = make_inp_str( " subar=", subar ) 

 

# ------------ Pc/Pe String ------------- 

pcope_str = make_inp_str( " pi/p=", PcOvPe ) 

 

 

# ------------------------------------------------ 

# set up rocket line with Pc, PC/Pe and Epsilon 

set_py_cea_line(N," rocket %s %s"%(eqfrStr,pc_str) + subar_str + pcope_str + eps_str ) 

 

 

# ------------ Finite Area Combustor String ------ 

 

#print('In setupCards, fac_CR =', self.fac_CR) 

if self.fac_CR is not None: 

N += 1 

fac_str = ' fac ' + make_inp_str(" ac/at=", self.fac_CR ) 

 

set_py_cea_line(N, fac_str ) 

 

self.i_injface = 0 

self.i_chm = 1 

self.i_thrt = 2 

self.i_exit = 3 

else: 

self.i_injface = 0 

self.i_chm = 0 

self.i_thrt = 1 

self.i_exit = 2 

 

 

N += 1 

 

if self.useMR : 

if ERphi != None: 

# use ER,phi as an input instead of MR 

# phi = Equivalence ratios in terms of fuel-to-oxidant weight ratios 

set_py_cea_line(N,"phi,eq.ratio=%f"%ERphi+" ") 

N += 1 

elif ERr != None: 

# use ER,r as an input instead of MR 

# r = Chemical equivalence ratios in terms of valences 

set_py_cea_line(N,"r,eq.ratio=%f"%ERr+" ") 

N += 1 

else: 

# use MR as input 

 

# ------------ Mixture Ratio String ------------- 

mr_str = make_inp_str(" o/f=", MR) 

 

set_py_cea_line(N, mr_str) 

N += 1 

else: 

set_py_cea_line(N," ") 

N += 1 

 

for i_line,line in enumerate([" "," "," ","end "]): 

if i_line == 2: 

line = 'output %s '%output 

if short_output: 

line += " short " 

if show_transport: 

line += " transport " 

if show_mass_frac: 

line += " massf " 

 

set_py_cea_line(N,line) 

N += 1 

 

# make sure to overwrite any lines from previous calls 

if N>_NLines_Max_ever: 

_NLines_Max_ever=N 

if _NLines_Max_ever>N: 

while N<_NLines_Max_ever: 

set_py_cea_line(N," ") 

N += 1 

 

# now call CEA 

myfile = "f.inp " # be sure to leave extra space at end 

 

readData = 1 

if (self is _last_called): readData = 0 

 

try: 

if self.readDatafileOnce and (self.desc==_last_called.desc): 

readData = 0 

except: 

print("ERROR reading data file for",self.desc) 

 

if readData: 

_last_called = self 

self.readDatafileOnce = 1 

if self.desc in _PrintCountDict: 

_PrintCountDict[self.desc] = _PrintCountDict[self.desc] + 1 

if _PrintCountDict[self.desc] % 100 == 0: 

print("reading cea isp data files for",self.desc,_PrintCountDict[self.desc],'times') 

else: 

#print("reading cea isp data files for",self.desc) 

_PrintCountDict[self.desc] = 1 

 

 

if self.make_debug_prints: 

if self.makeOutput: 

print("NOTICE... making an output file") 

 

# Before calling CEA, init values to zero so bad run can be detected 

py_cea.rockt.vaci[ self.i_thrt ] = 0.0 # Vacuum Isp at throat 

py_cea.rockt.vaci[ self.i_exit ] = 0.0 # Vacuum Isp at exit 

py_cea.rockt.cstr = 0.0 # cstar 

py_cea.prtout.ttt[ self.i_chm ] = 0.0 # chamber temperature 

py_cea.rockt.app[ self.i_thrt ] = 0.0 # Pc/Pt 

py_cea.rockt.app[ self.i_exit ] = 0.0 # Pc/Pe 

py_cea.rockt.aeat[ self.i_exit ] = 0.0 # exit area/throat area 

py_cea.rockt.vmoc[ self.i_exit ] = 0.0 

py_cea.miscr.eqrat = 0.0 # equivalence ratio 

 

for i in range(3): 

py_cea.rockt.sonvel[i] = 0.0 

py_cea.prtout.hsum[i] = 0.0 

py_cea.prtout.wm[i] = 0.0 

py_cea.prtout.gammas[i] = 0.0 

py_cea.prtout.vlm[i] = 0.0 

py_cea.prtout.cpr[i] = 0.0 

 

py_cea.trpts.vis[i] = 0.0 # viscosity 

py_cea.trpts.cpeql[i] = 0.0 # equilibrium specific heat 

py_cea.trpts.coneql[i] = 0.0 # equilibrium thermal conductivity 

py_cea.trpts.preql[i] = 0.0 # equilibrium prandtl number 

py_cea.trpts.cpfro[i] = 0.0 # frozen specific heat 

py_cea.trpts.confro[i] = 0.0 # frozen thermal conductivity 

py_cea.trpts.prfro[i] = 0.0 # frozen prandtl number 

 

# set species concentrations to 0.0 prior to calcs 

#for k,p in enumerate(py_cea.cdata.prod): 

# for i in range(3): 

# py_cea.comp.en[k-1,i] = 0.0 

# py_cea.therm.mw[k-1] = 0.0 

# if k>=50: 

# break 

 

 

#print( 'calling py_cea with pathPrefix and myfile=' ) 

#print( '"'+self.pathPrefix+'"',' and ', '"'+myfile+'"' ) 

py_cea.py_cea(self.pathPrefix, myfile, self.makeOutput, readData) 

 

def get_full_cea_output(self, Pc=100.0, MR=1.0, eps=40.0, subar=None, PcOvPe=None, 

frozen=0, frozenAtThroat=0, short_output=0, show_transport=1, 

pc_units='psia', output='calories', show_mass_frac=False, 

fac_CR=None): 

""" 

Get the full output file created by CEA. Return as a string.:: 

 

#: Pc = combustion end pressure 

#: eps = Nozzle Expansion Area Ratio 

#: pc_units = 'psia', 'bar', 'atm', 'mmh'(mm of mercury) 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

#: fac_CR = Contraction Ratio of finite area combustor, (None=infinite) 

""" 

 

# regardless of how run was set up, change makeOutput flag True 

save_flag = self.makeOutput 

self.makeOutput = True 

 

# Allow user to override fac_CR from CEA_Obj __init__ 

save_fac_CR = self.fac_CR 

if fac_CR is not None: 

self.fac_CR = fac_CR 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, subar=subar, PcOvPe=PcOvPe, 

frozen=frozen, frozenAtThroat=frozenAtThroat, 

short_output=short_output, 

show_transport=show_transport, pc_units=pc_units, 

output=output, show_mass_frac=show_mass_frac) 

 

self.makeOutput = save_flag # restore makeOutput 

self.fac_CR = save_fac_CR # restore fac_CR 

 

return open( os.path.join(ROCKETCEA_DATA_DIR,'f.out'),'r').read() 

 

 

def get_Pinj_over_Pcomb(self, Pc=100.0, MR=1.0, fac_CR=None): 

""" 

Get the pressure ratio of Pinjector / Pchamber.:: 

 

#: Pc = combustion end pressure (psia) 

#: fac_CR = Contraction Ratio of finite area combustor, (None=infinite) 

""" 

 

# Allow user to override fac_CR from CEA_Obj __init__ 

save_fac_CR = self.fac_CR 

if fac_CR is not None: 

self.fac_CR = fac_CR 

 

if self.fac_CR is None: 

print('ERROR in get_Pinj_over_Pcomb... Need value for fac_CR') 

raise Exception('ERROR in get_Pinj_over_Pcomb... Need value for fac_CR') 

 

self.setupCards( Pc=Pc, MR=MR ) 

 

self.fac_CR = save_fac_CR # restore fac_CR 

 

Pinj_over_Pcomb = py_cea.prtout.ppp[0] / py_cea.prtout.ppp[1] 

 

return Pinj_over_Pcomb 

 

 

def __call__(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

"""Returns IspVac(sec) if CEA_Obj is simply called like a function.""" 

return self.get_Isp(Pc=Pc, MR=MR, eps=eps, 

frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

def get_IvacCstrTc(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return the tuple (IspVac, Cstar, Tcomb)in(sec, ft/sec, degR) 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: MR is only used for ox/fuel combos. 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

 

cacheDesc1 = (Pc,MR,eps, frozen, frozenAtThroat) 

try: 

IspVac = _CacheObjDict[ self.desc ].getIsp( cacheDesc1 ) 

except: 

IspVac = None 

 

# don't bother looking at Cstar and Tc if there's no Isp 

cacheDesc2 = (Pc,MR, frozen, frozenAtThroat) 

if IspVac: 

try: 

Cstar = _CacheObjDict[ self.desc ].getCstar( cacheDesc2 ) 

TcK = _CacheObjDict[ self.desc ].getTcK( cacheDesc2 ) 

except: 

Cstar = None 

TcK = None 

if Cstar and TcK: 

Tcomb = TcK * 1.8 # convert from Kelvin to Rankine 

return IspVac, Cstar, Tcomb 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

#print( "py_cea.rockt.vaci",py_cea.rockt.vaci ) 

IspVac = py_cea.rockt.vaci[ self.i_exit ] 

#print('py_cea.rockt.cstr',py_cea.rockt.cstr) 

#print( 'py_cea.rockt.app', py_cea.rockt.app ) 

Cstar = float(py_cea.rockt.cstr) 

 

#print( "py_cea.prtout.ttt",py_cea.prtout.ttt ) 

TcK = py_cea.prtout.ttt[ self.i_chm ] 

Tcomb = TcK * 1.8 # convert from Kelvin to Rankine 

_CacheObjDict[ self.desc ].setIsp( cacheDesc1, IspVac ) 

_CacheObjDict[ self.desc ].setCstar( cacheDesc2, Cstar ) 

_CacheObjDict[ self.desc ].setTcK( cacheDesc2, TcK ) 

return IspVac, Cstar, Tcomb 

 

def getFrozen_IvacCstrTc(self, Pc=100.0, MR=1.0, eps=40.0, frozenAtThroat=0): 

""":: 

 

#: Return the tuple (IspFrozen, Cstar, Tcomb)in(sec, ft/sec, degR) 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: MR is only used for ox/fuel combos. 

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=1, frozenAtThroat=frozenAtThroat) 

IspFrozen = py_cea.rockt.vaci[ self.i_exit ] 

Cstar = float(py_cea.rockt.cstr) 

TcK = py_cea.prtout.ttt[ self.i_chm ] 

Tcomb = TcK * 1.8 # convert from Kelvin to Rankine 

return IspFrozen, Cstar, Tcomb 

 

def get_IvacCstrTc_exitMwGam(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: return the tuple (IspVac, Cstar, Tcomb, mw, gam)in(sec, ft/sec, degR, lbm/lbmole, -) 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: mw and gam apply to nozzle exit. 

#: MR is only used for ox/fuel combos. 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

#print( "py_cea.rockt.vaci",py_cea.rockt.vaci ) 

IspVac = py_cea.rockt.vaci[ self.i_exit ] 

Cstar = float(py_cea.rockt.cstr) 

Tcomb = py_cea.prtout.ttt[ self.i_chm ] * 1.8 # convert from Kelvin to Rankine 

mw,gam = py_cea.prtout.wm[ self.i_exit ], py_cea.prtout.gammas[ self.i_exit ] 

 

return IspVac, Cstar, Tcomb, mw, gam 

 

 

def get_IvacCstrTc_ChmMwGam(self, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: return the tuple (IspVac, Cstar, Tcomb, mw, gam)in(sec, ft/sec, degR, lbm/lbmole, -) 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: mw and gam apply to chamber. 

#: MR is only used for ox/fuel combos. 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps) 

 

#print( "py_cea.rockt.vaci",py_cea.rockt.vaci ) 

IspVac = py_cea.rockt.vaci[ self.i_exit ] 

Cstar = float(py_cea.rockt.cstr) 

Tcomb = py_cea.prtout.ttt[ self.i_chm ] * 1.8 # convert from Kelvin to Rankine 

mw,gam = py_cea.prtout.wm[ self.i_chm ], py_cea.prtout.gammas[ self.i_chm ] 

 

return IspVac, Cstar, Tcomb, mw, gam 

 

def get_IvacCstrTc_ThtMwGam(self, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: return the tuple (IspVac, Cstar, Tcomb, mw, gam)in(sec, ft/sec, degR, lbm/lbmole, -) 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: mw and gam apply to throat. 

#: MR is only used for ox/fuel combos. 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps) 

 

#print( "py_cea.rockt.vaci",py_cea.rockt.vaci ) 

IspVac = py_cea.rockt.vaci[ self.i_exit ] 

Cstar = float(py_cea.rockt.cstr) 

Tcomb = py_cea.prtout.ttt[ self.i_chm ] * 1.8 # convert from Kelvin to Rankine 

mw,gam = py_cea.prtout.wm[ self.i_thrt ], py_cea.prtout.gammas[ self.i_thrt ] 

 

return IspVac, Cstar, Tcomb, mw, gam 

 

def get_Isp(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: return IspVac (sec) 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: MR is only used for ox/fuel combos. 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

cacheDesc1 = (Pc,MR,eps, frozen, frozenAtThroat) 

try: 

IspVac = _CacheObjDict[ self.desc ].getIsp( cacheDesc1 ) 

except: 

IspVac = None 

if IspVac: 

return IspVac 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

IspVac = py_cea.rockt.vaci[ self.i_exit ] 

_CacheObjDict[ self.desc ].setIsp( cacheDesc1, IspVac ) 

#print( 'py_cea.rockt.vaci',py_cea.rockt.vaci ) 

#print( 'py_cea.rockt.cstr',py_cea.rockt.cstr ) 

return IspVac 

 

def get_Cstar(self, Pc=100.0, MR=1.0): 

""":: 

 

#: return Cstar (ft/sec) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

""" 

cacheDesc2 = (Pc,MR,0,0) # set frozen flags to zero in cache description 

try: 

Cstar = _CacheObjDict[ self.desc ].getCstar( cacheDesc2 ) 

except: 

Cstar = None 

if Cstar: 

return Cstar 

 

 

self.setupCards( Pc=Pc, MR=MR, eps=2.0) 

Cstar = float(py_cea.rockt.cstr) 

_CacheObjDict[ self.desc ].setCstar( cacheDesc2, Cstar ) 

return Cstar 

 

def get_Tcomb(self, Pc=100.0, MR=1.0): 

""":: 

 

#: return Tcomb (degR) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

""" 

cacheDesc2 = (Pc,MR,0,0) # set frozen flags to zero in cache description 

try: 

TcK = _CacheObjDict[ self.desc ].getTcK( cacheDesc2 ) 

Tcomb = TcK * 1.8 # convert from Kelvin to Rankine 

except: 

TcK = None 

Tcomb = None 

if Tcomb: 

return Tcomb 

 

self.setupCards( Pc=Pc, MR=MR, eps=2.0) 

TcK = py_cea.prtout.ttt[ self.i_chm ] 

Tcomb = TcK * 1.8 # convert from Kelvin to Rankine 

_CacheObjDict[ self.desc ].setTcK( cacheDesc2, TcK ) 

return Tcomb 

 

def get_PcOvPe(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: return Pc / Pexit. 

#: Pc = combustion end pressure (psia) 

#: eps = Nozzle Expansion Area Ratio 

#: MR is only used for ox/fuel combos. 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

PcOvPe = py_cea.rockt.app[ self.i_exit ] 

if self.fac_CR is not None: 

PcOvPe = PcOvPe * py_cea.rockt.app[ self.i_chm ] 

 

#print( 'py_cea.rockt.app',py_cea.rockt.app ) 

#Pexit = py_cea.prtout.ppp[ self.i_exit ]*14.7/1.01325 

#return Pc/Pexit 

return PcOvPe 

 

def get_eps_at_PcOvPe(self, Pc=100.0, MR=1.0, PcOvPe=1000.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Given a Pc/Pexit, return the Area Ratio that applies. 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, PcOvPe=PcOvPe, frozen=frozen, frozenAtThroat=frozenAtThroat) 

eps = py_cea.rockt.aeat[ self.i_exit ] 

#print( 'py_cea.rockt.aeat',py_cea.rockt.aeat ) 

return eps 

 

def get_Throat_PcOvPe(self, Pc=100.0, MR=1.0): 

""":: 

 

#: return Pc/Pexit at throat. 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=2.0) 

PcOvPe = py_cea.rockt.app[ self.i_thrt ] 

if self.fac_CR is not None: 

PcOvPe = PcOvPe * py_cea.rockt.app[ self.i_chm ] 

return PcOvPe 

 

def get_MachNumber(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: return nozzle exit mach number. 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

M = py_cea.rockt.vmoc[ self.i_exit ] 

return M 

 

def get_Chamber_MachNumber(self, Pc=100.0, MR=1.0, fac_CR=None): 

""":: 

 

#: Return mach numbers at the chamber 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: fac_CR = Contraction Ratio of finite area combustor, (None=infinite) 

""" 

# Allow user to override fac_CR from CEA_Obj __init__ 

save_fac_CR = self.fac_CR 

if fac_CR is not None: 

self.fac_CR = fac_CR 

 

if self.fac_CR is None: 

print('ERROR in get_Chamber_MachNumber... Need value for fac_CR') 

raise Exception('ERROR in get_Chamber_MachNumber... Need value for fac_CR') 

 

self.setupCards( Pc=Pc, MR=MR ) 

 

self.fac_CR = save_fac_CR # restore fac_CR 

 

M = py_cea.rockt.vmoc[ 1 ] 

return M 

 

def get_Temperatures(self, Pc=100.0, MR=1.0,eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return a list of temperatures at the chamber, throat and exit (degR) 

#: (Note frozen flag determins whether Texit is equilibrium or Frozen temperature) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

""" 

#self.setupCards( Pc=Pc, MR=MR, eps=eps) 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

# convert from Kelvin to Rankine 

#tempList = 1.8 * py_cea.prtout.ttt[:3] 

if self.fac_CR is not None: 

tempList = list( py_cea.prtout.ttt[1:4] ) 

else: 

tempList = list( py_cea.prtout.ttt[:3] ) 

 

tempList = [1.8*T for T in tempList] 

return tempList # Tc, Tthroat, Texit 

 

 

def get_SonicVelocities(self, Pc=100.0, MR=1.0,eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return a list of sonic velocities at the chamber, throat and exit (ft/sec) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

# convert from m/sec into ft/sec 

if self.fac_CR is not None: 

sonicList = list(py_cea.rockt.sonvel[1:4]) 

else: 

sonicList = list(py_cea.rockt.sonvel[:3]) 

 

sonicList = [v * 3.28083 for v in sonicList] 

return sonicList 

 

def get_Chamber_SonicVel(self, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: Return the sonic velocity in the chamber (ft/sec) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

""" 

sonicList = self.get_SonicVelocities( Pc=Pc, MR=MR, eps=eps) 

return sonicList[ 0 ] # 0 == self.i_chm here 

 

 

def get_Entropies(self, Pc=100.0, MR=1.0,eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return a list of entropies at the chamber, throat and exit CAL/(G)(K) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

if self.fac_CR is not None: 

sList = list(py_cea.prtout.ssum[1:4]) 

else: 

sList = list(py_cea.prtout.ssum[:3]) 

 

for i,s in enumerate( sList ): 

sList[i] = s * 8314.51 / 4184.0 # convert into CAL/(G)(K) 

return sList 

 

def get_Enthalpies(self, Pc=100.0, MR=1.0,eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return a list of enthalpies at the chamber, throat and exit (BTU/lbm) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

if self.fac_CR is not None: 

hList = list(py_cea.prtout.hsum[1:4]) 

else: 

hList = list(py_cea.prtout.hsum[:3]) 

 

for i,h in enumerate( hList ): 

hList[i] = h * 1.8 * 8314.51 / 4184.0 # convert into BTU/lbm 

return hList 

 

def get_SpeciesMassFractions(self, Pc=100.0, MR=1.0,eps=40.0, 

frozen=0, frozenAtThroat=0, min_fraction=0.000005): 

""":: 

 

#: Returns species mass fractions at the injector face, chamber, throat and exit. 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

#: Returns 2 dictionaries 

#: molWtD dictionary: index=species: value=molecular weight 

#: massFracD dictionary: index=species: value=[massfrac_injface, massfrac_chm, massfrac_tht, massfrac_exit] 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

massFracD = {} # index=species: value=[massfrac_chm, massfrac_tht, massfrac_exit] 

molWtD = {} # index=species: value=molecular weight 

 

for k in range( py_cea.indx.ngc ): 

p = py_cea.cdata.prod[k] 

p = p.decode("utf-8").strip() 

if p: 

sL = [] 

mfL = [] 

gt_zero = False 

#for i in range(3): 

for i in [self.i_injface, self.i_chm, self.i_thrt, self.i_exit]: 

en = py_cea.comp.en[k-1,i] 

mw = py_cea.therm.mw[k-1] 

 

mfL.append( en*mw ) 

if mfL[-1] >= min_fraction: # default = 0.000005 

gt_zero = True 

 

if gt_zero: 

if frozen: 

if frozenAtThroat: 

mfL = [ mfL[0], mfL[1], mfL[2], mfL[2] ] 

else: 

mfL = [ mfL[0] for _ in mfL ] 

 

massFracD[p] = mfL 

molWtD[p] = mw 

 

return molWtD, massFracD 

 

def get_SpeciesMoleFractions(self, Pc=100.0, MR=1.0,eps=40.0, 

frozen=0, frozenAtThroat=0, min_fraction=0.000005): 

""":: 

 

#: Returns species mole fractions at the injector face, chamber, throat and exit. 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

#: Returns 2 dictionaries 

#: molWtD dictionary: index=species: value=molecular weight 

#: moleFracD dictionary: index=species: value=[molefrac_injface, molefrac_chm, molefrac_tht, molefrac_exit] 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

moleFracD = {} # index=species: value=[molefrac_chm, molefrac_tht, molefrac_exit] 

molWtD = {} # index=species: value=molecular weight 

 

for k in range( py_cea.indx.ngc ): 

p = py_cea.cdata.prod[k] 

p = p.decode("utf-8").strip() 

if p: 

sL = [] 

mfL = [] 

gt_zero = False 

#for i in range(3): 

for i in [self.i_injface, self.i_chm, self.i_thrt, self.i_exit]: 

en = py_cea.comp.en[k-1,i] 

totn = py_cea.prtout.totn[i] 

mw = py_cea.therm.mw[k-1] 

 

mfL.append( en/totn ) 

if mfL[-1] >= min_fraction: # default = 0.000005 

gt_zero = True 

 

if gt_zero: 

if frozen: 

if frozenAtThroat: 

mfL = [ mfL[0], mfL[1], mfL[2], mfL[2] ] 

else: 

mfL = [ mfL[0] for _ in mfL ] 

 

moleFracD[p] = mfL 

molWtD[p] = mw 

return molWtD, moleFracD 

 

def get_Chamber_H(self, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: Return the enthalpy in the chamber (BTU/lbm) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

""" 

hList = self.get_Enthalpies( Pc=Pc, MR=MR, eps=eps) 

return hList[ 0 ] # BTU/lbm # 0 == self.i_chm here 

 

 

def get_Densities(self, Pc=100.0, MR=1.0,eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return a list of densities at the chamber, throat and exit(lbm/cuft) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

if self.fac_CR is not None: 

dList = list(py_cea.prtout.vlm[1:4]) 

else: 

dList = list(py_cea.prtout.vlm[:3]) 

 

for i,v in enumerate( dList ): 

dList[i] = 62.42796 * 100.0 / v # convert into lbm/cuft 

return dList 

 

def get_Chamber_Density(self, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: Return the density in the chamber(lbm/cuft) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

""" 

dList = self.get_Densities( Pc=Pc, MR=MR, eps=eps) 

return dList[ 0 ] # lbm/cuft # 0 == self.i_chm here 

 

 

def get_HeatCapacities(self, Pc=100.0, MR=1.0,eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: Return a list of heat capacities at the chamber, throat and exit(BTU/lbm degR) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

# convert from m/sec into ft/sec 

if self.fac_CR is not None: 

cpList = list(py_cea.prtout.cpr[1:4]) 

else: 

cpList = list(py_cea.prtout.cpr[:3]) 

 

for i,cp in enumerate( cpList ): 

cpList[i] = cp * 8314.51 / 4184.0 # convert into BTU/lbm degR (aka cal/gm K) 

return cpList 

 

def get_Chamber_Cp(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0): 

""":: 

 

#: Return the heat capacity in the chamber(BTU/lbm degR) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag (0=equilibrium, 1=frozen) 

""" 

cpList = self.get_HeatCapacities( Pc=Pc, MR=MR, eps=eps, frozen=frozen) 

return cpList[ 0 ] # BTU/lbm degR # 0 == self.i_chm here 

 

def get_Throat_Isp(self, Pc=100.0, MR=1.0, frozen=0): 

""":: 

 

#: Return the IspVac for the throat(sec). 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: frozen = flag (0=equilibrium, 1=frozen) 

""" 

eps=1.0 

cacheDesc1 = (Pc,MR,eps,frozen,0) # set frozen flag to zero in cache description 

try: 

IspVac = _CacheObjDict[ self.desc ].getIsp( cacheDesc1 ) 

except: 

IspVac = None 

if IspVac: 

return IspVac 

 

self.setupCards( Pc=Pc, MR=MR, eps=2.0, frozen=frozen) 

 

IspVac = py_cea.rockt.vaci[ self.i_thrt ] 

_CacheObjDict[ self.desc ].setIsp( cacheDesc1, IspVac ) 

#print( 'py_cea.rockt.vaci',py_cea.rockt.vaci ) 

#print( 'py_cea.rockt.cstr',py_cea.rockt.cstr ) 

return IspVac 

 

 

def get_Chamber_MolWt_gamma(self, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: return the tuple (mw, gam) for the chamber (lbm/lbmole, -) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

""" 

#common /prtout/ cpr,dlvpt,dlvtp,gammas,hsum,ppp,ssum,totn,ttt,vlm,wm,pltout 

self.setupCards( Pc=Pc, MR=MR, eps=eps) 

 

mw,gam = py_cea.prtout.wm[ self.i_chm ], py_cea.prtout.gammas[ self.i_chm ] 

return mw,gam 

 

def get_Throat_MolWt_gamma(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0): 

""":: 

 

#: return the tuple (mw, gam) for the throat (lbm/lbmole, -) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

""" 

#common /prtout/ cpr,dlvpt,dlvtp,gammas,hsum,ppp,ssum,totn,ttt,vlm,wm,pltout 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen) 

 

mw,gam = py_cea.prtout.wm[ self.i_thrt ], py_cea.prtout.gammas[ self.i_thrt ] 

return mw,gam 

 

def get_exit_MolWt_gamma(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0, frozenAtThroat=0): 

""":: 

 

#: return the tuple (mw, gam) for the nozzle exit (lbm/lbmole, -) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen = flag (0=equilibrium, 1=frozen) 

#: frozenAtThroat = flag 0=frozen in chamber, 1=frozen at throat 

""" 

#common /prtout/ cpr,dlvpt,dlvtp,gammas,hsum,ppp,ssum,totn,ttt,vlm,wm,pltout 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

mw,gam = py_cea.prtout.wm[ self.i_exit ], py_cea.prtout.gammas[ self.i_exit ] 

return mw,gam 

 

 

def get_eqratio(self, Pc=100.0, MR=1.0, eps=40.0): 

'''Returns BOTH ERr and ERphi (valence basis and mass basis respectively)''' 

#common /miscr/ a,atwt,avgdr,boltz,b0,eqrat,... 

self.setupCards( Pc=Pc, MR=MR, eps=eps) 

 

ERr = py_cea.miscr.eqrat 

try: # the logic below is lifted directly from the CEA FORTRAN source code 

tem = (py_cea.inpt.vpls[ self.i_chm ]+py_cea.inpt.vmin[ self.i_chm ])*py_cea.miscr.oxfl 

ERphi = -(py_cea.inpt.vmin[ self.i_thrt ]+py_cea.inpt.vpls[ self.i_thrt ])/tem 

except: 

ERphi = 0.0 

 

return float(ERr), float(ERphi) 

 

def getMRforER(self, ERphi=None, ERr=None): 

""":: 

 

#: return the value of mixture ratio that applies to the input equivalence ratio. 

#: Can be ERr or ERphi (valence basis and mass basis respectively) 

""" 

#common /miscr/ a,atwt,avgdr,boltz,b0,eqrat,... 

 

if ERphi != None: 

self.setupCards( Pc=100.0, ERphi=ERphi, eps=40.0 ) 

MR = py_cea.miscr.oxfl 

elif ERr != None: 

self.setupCards( Pc=100.0, ERr=ERr, eps=40.0 ) 

MR = py_cea.miscr.oxfl 

else: 

print('WARNING... ERROR in call to getMRforER. No ER value input') 

MR = 0.0 #ERROR 

 

#self.setupCards( Pc=100.0, MR=1.0, eps=40.0 ) # fix any mismatches in system from ER call 

return float(MR) 

 

def get_description(self): 

"""Return a string description of the propellant(s). e.g. 'LOX / MMH'""" 

return str(self.desc) 

 

def estimate_Ambient_Isp(self, Pc=100.0, MR=1.0, eps=40.0, Pamb=14.7, 

frozen=0, frozenAtThroat=0): 

""":: 

 

#: return the tuple (IspAmb, mode) 

#: Use throat gam to run ideal separation calculations. 

#: mode is a string containing, UnderExpanded, OverExpanded, or Separated 

#: Pc = combustion end pressure (psia) 

#: Pamb ambient pressure (e.g. sea level=14.7 psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag, 0=equilibrium, 1=frozen  

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

""" 

 

self.setupCards( Pc=Pc, MR=MR, eps=eps, frozen=frozen, frozenAtThroat=frozenAtThroat) 

 

IspVac = py_cea.rockt.vaci[ self.i_exit ] 

mw,gam = py_cea.prtout.wm[ self.i_thrt ], py_cea.prtout.gammas[ self.i_thrt ] # throat gamma 

#PcOvPe = py_cea.rockt.app[ self.i_exit ] 

Pexit = py_cea.prtout.ppp[ self.i_exit ]*14.7/1.01325 

#print( "=============== Pexit ", Pexit, py_cea.prtout.ppp[ self.i_exit ]/1.01325, py_cea.prtout.ppp[ self.i_exit ] ) 

Cstar = float(py_cea.rockt.cstr) 

# ================================== 

 

CfOvCfvacAtEsep, CfOvCfvac, Cfsep, CfiVac, CfiAmbSimple, CfVac, epsSep, Psep = \ 

sepNozzleCf(gam, eps, Pc, Pamb) 

 

if Pexit > Psep: 

# if not separated, use theoretical equation for back-pressure correction 

IspAmb = IspVac - Cstar*Pamb*eps/Pc/32.174 

CfAmb = IspAmb * 32.174 / Cstar 

else: 

# if separated, use Kalt and Badal estimate of ambient thrust coefficient 

# NOTE: there are better, more modern methods available 

IspODEepsSep,CstarODE,Tc = \ 

self.get_IvacCstrTc(Pc=Pc, MR=MR, eps=epsSep) 

 

CfvacAtEsep = CfVac * IspODEepsSep / IspVac 

 

CfAmb = CfvacAtEsep * CfOvCfvacAtEsep 

IspAmb = CfAmb * Cstar / 32.174 

 

# figure out mode of nozzle operation 

if Pexit > Psep: 

if Pexit > Pamb + 0.05: 

mode = 'UnderExpanded (Pe=%g)'%Pexit 

elif Pexit < Pamb - 0.05: 

mode = 'OverExpanded (Pe=%g)'%Pexit 

else: 

mode = 'Pexit = %g'%Pexit 

else: 

mode = 'Separated (Psep=%g, epsSep=%g)'%(Psep,epsSep) 

 

return IspAmb, mode 

 

 

def get_PambCf(self, Pamb=14.7, Pc=100.0, MR=1.0, eps=40.0): 

""":: 

 

#: Return the Thrust Coefficient (CF) for equilibrium chemistry and ambient pressure 

#: Pc = combustion end pressure (psia) 

#: Pamb ambient pressure (e.g. sea level=14.7 psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

""" 

 

IspAmb, mode = self.estimate_Ambient_Isp( Pc=Pc, MR=MR, eps=eps, Pamb=Pamb) 

Cstar = float(py_cea.rockt.cstr) 

 

CFamb = GC * IspAmb / Cstar 

CFcea = GC * float(py_cea.rockt.spim[ self.i_exit ]) / Cstar 

 

return CFcea, CFamb, mode 

 

def getFrozen_PambCf(self, Pamb=0.0, Pc=100.0, MR=1.0, eps=40.0, frozenAtThroat=0): 

""":: 

 

#: Return the Thrust Coefficient (CF) for frozen chemistry and ambient pressure 

#: Pc = combustion end pressure (psia) 

#: Pamb ambient pressure (e.g. sea level=14.7 psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozenAtThroat flag, 0=frozen in chamber, 1=frozen at throat 

""" 

 

IspAmb, mode = self.estimate_Ambient_Isp( Pc=Pc, MR=MR, eps=eps, Pamb=Pamb, 

frozen=1, frozenAtThroat=frozenAtThroat) 

Cstar = float(py_cea.rockt.cstr) 

 

CFfrozen = GC * IspAmb / Cstar 

CFcea = GC * float(py_cea.rockt.spim[ self.i_exit ]) / Cstar 

 

return CFcea,CFfrozen, mode 

 

def get_Chamber_Transport(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0): 

""":: 

 

#: Return a list of heat capacity, viscosity, thermal conductivity and Prandtl number 

#: in the chamber. (units are default printout units) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio... has no effect on chamber properties 

#: frozen flag (0=equilibrium, 1=frozen) 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, show_transport=1) 

 

if frozen: 

Cp = py_cea.trpts.cpfro[ self.i_chm ] 

visc = py_cea.trpts.vis[ self.i_chm ] 

cond = py_cea.trpts.confro[ self.i_chm ] 

Prandtl = py_cea.trpts.prfro[ self.i_chm ] 

else: 

Cp = py_cea.trpts.cpeql[ self.i_chm ] 

visc = py_cea.trpts.vis[ self.i_chm ] 

cond = py_cea.trpts.coneql[ self.i_chm ] 

Prandtl = py_cea.trpts.preql[ self.i_chm ] 

 

return Cp, visc, cond, Prandtl 

 

def get_Throat_Transport(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0): 

""":: 

 

#: Return a list of heat capacity, viscosity, thermal conductivity and Prandtl number 

#: in the throat. (units are default printout units) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio... has no effect on throat properties 

#: frozen flag (0=equilibrium, 1=frozen) 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, show_transport=1) 

 

if frozen: 

Cp = py_cea.trpts.cpfro[ self.i_thrt ] 

visc = py_cea.trpts.vis[ self.i_thrt ] 

cond = py_cea.trpts.confro[ self.i_thrt ] 

Prandtl = py_cea.trpts.prfro[ self.i_thrt ] 

else: 

Cp = py_cea.trpts.cpeql[ self.i_thrt ] 

visc = py_cea.trpts.vis[ self.i_thrt ] 

cond = py_cea.trpts.coneql[ self.i_thrt ] 

Prandtl = py_cea.trpts.preql[ self.i_thrt ] 

 

return Cp, visc, cond, Prandtl 

 

def get_Exit_Transport(self, Pc=100.0, MR=1.0, eps=40.0, frozen=0): 

""":: 

 

#: Return a list of heat capacity, viscosity, thermal conductivity and Prandtl number 

#: at the exit. (units are default printout units) 

#: Pc = combustion end pressure (psia) 

#: MR is only used for ox/fuel combos. 

#: eps = Nozzle Expansion Area Ratio 

#: frozen flag (0=equilibrium, 1=frozen) 

""" 

self.setupCards( Pc=Pc, MR=MR, eps=eps, show_transport=1) 

 

if frozen: 

Cp = py_cea.trpts.cpfro[ self.i_exit ] 

visc = py_cea.trpts.vis[ self.i_exit ] 

cond = py_cea.trpts.confro[ self.i_exit ] 

Prandtl = py_cea.trpts.prfro[ self.i_exit ] 

else: 

Cp = py_cea.trpts.cpeql[ self.i_exit ] 

visc = py_cea.trpts.vis[ self.i_exit ] 

cond = py_cea.trpts.coneql[ self.i_exit ] 

Prandtl = py_cea.trpts.preql[ self.i_exit ] 

 

return Cp, visc, cond, Prandtl 

 

 

# ----------------------- DEBUG OUTPUT ----------------------------- 

def print_py_cea_vars(): 

""" 

Print all the interface variables to the FORTRAN pyd file. 

Normally used for debugging or verifying FORTRAN internal values. 

""" 

commonL = dir(py_cea) 

for common in commonL: 

if common[:1] != '_': 

print(common) 

vL = dir( getattr(py_cea,common) ) 

print(vL) 

for v in vL: 

var = getattr( getattr(py_cea,common), v) 

print(v,var) 

print() 

 

 

if __name__ == '__main__': 

 

from pylab import * 

 

 

def showOutput( ispObj ): 

print() 

print(ispObj.desc,' at Pc=%.1f, MR=%.3f, eps=%.2f...'%(Pc,MR,eps)) 

i,c,t = ispObj.get_IvacCstrTc(Pc,MR,eps) 

print('Isp = ',i) 

print('Cstar = ',c) 

print('Tcomb = ',t) 

print(' at eps =',eps) 

PcOvPe = ispObj.get_PcOvPe(Pc=Pc, MR=MR, eps=eps) 

print('PcOvPe = ',PcOvPe) 

epsAtPcOvPe = ispObj.get_eps_at_PcOvPe(Pc=Pc, MR=MR, PcOvPe=PcOvPe) 

print('epsAtPcOvPe=',epsAtPcOvPe) 

print('Mach Number=',ispObj.get_MachNumber(Pc=Pc, MR=MR, eps=eps)) 

print() 

print('Chamber Sonic Vel =',ispObj.get_Chamber_SonicVel( Pc=Pc, MR=MR,eps=eps)) 

print('Enthalpies =',ispObj.get_Enthalpies( Pc=Pc, MR=MR,eps=eps)) 

print('Densities =',ispObj.get_Densities( Pc=Pc, MR=MR,eps=eps)) 

print('Cp =',ispObj.get_HeatCapacities( Pc=Pc, MR=MR,eps=eps)) 

print('=======================================') 

 

Pc,MR,eps = 1000.0, 1.0, 30.0 

ispNew = CEA_Obj(fuelName="MMH", oxName="N2O4") 

showOutput( ispNew ) 

 

#Cp, visc, cond, Pr = ispNew.get_Exit_Transport(Pc=1000.0, MR=6.0, eps=40.0, frozen=1) 

#print('Cp=%g, visc=%g, cond=%g, Pr=%g'%(Cp, visc, cond, Pr) ) 

#sys.exit() 

 

ispNew = CEA_Obj(propName="ARC311") 

showOutput( ispNew ) 

 

ispNew = CEA_Obj(propName="N2O") 

showOutput( ispNew ) 

 

ispNew = CEA_Obj(oxName="LOX", fuelName="H2") 

showOutput( ispNew ) 

 

ispNew = CEA_Obj(oxName="LOX", fuelName="GH2_160") 

showOutput( ispNew ) 

 

print() 

print('amb_'*14) 

C = CEA_Obj(oxName="LOX", fuelName="H2") 

MR = 6.0 

for Pc in [100., 500., 1500., 5000.]: 

for eps in [2.0, 5., 10., 20., 50., 100.]: 

 

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=%10.2f IspVac=%10.2f Mode=%s'%(int(Pc),int(eps), IspAmb, IspVac, mode)) 

print(' ---')