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313 | # Applied Python PRISM
# (PRISM) PaRametrIc System Model
#
# Written by Charlie Taylor <cet@appliedpython.com>
# Feb 4, 2008
from prism.props.refprop7.n_dll_fluid import n_fluid
from prism.isp import Nozzle_Eff
from math import *
from prism.press.blowdownTfinal import Bottle
from prism.isp import isp
from prism.MassItem import MassItem
from prism.Summary import Summary
#C THIS ROUTINE CALCULATES COLD GAS ACS Isp and Total Impulse
#C
#C Assume that the gas is regulated to some Pc value
#C
class ColdGasACS( MassItem ):
def __init__(self, name="Cold Gas ACS", gasSymbol='N2', mass_lbm=0.0,
MEOP=5000., Pamb=0.0, AreaRatio=8., ThrustAmb=1.0,
Vbottle=1000.0,PcRegulated=350.0, dPregFinal=150.0,
TminR=500.0,TmaxR=550.0, fracIsentropic=None,
gammaPolyMin=1.0, ItotGoal=None,
tAction=100., isBell=0, pcentBell=80.0, halfAngDeg=15.0, etaNozInp=None,
hcBottleInp=None):
MassItem.__init__(self, name, type="pressurant")
self.Vbottle=Vbottle
self.ItotGoal = ItotGoal # if input, then set Vbottle from total impulse desired
self.ThrustAmb = ThrustAmb
self.dPregFinal=dPregFinal
self.MEOP = MEOP
self.Pamb = Pamb
self.AreaRatio = AreaRatio
self.PcRegulated=PcRegulated
self.TminR=TminR
self.TmaxR=TmaxR
self.fracIsentropic=fracIsentropic
self.gammaPolyMin=gammaPolyMin
self.symbol = gasSymbol
self.gasObj = n_fluid(gasSymbol,T=TmaxR,P=MEOP, child=1)
self.gammaIsen=self.gasObj.gamma()
# initialize Tfinal bottle calc
self.bottle = None
self.tAction = tAction
self.isBell = isBell
self.pcentBell = pcentBell
self.halfAngDeg = halfAngDeg
self.etaNozInp = etaNozInp
self.hcBottleInp = hcBottleInp
self.reCalc()
def buildSummary(self):
summ = Summary( summName='Cold Gas %s(%s) ACS'%(self.gasObj.name,self.symbol) ,
componentName=self.name, mass_lbm=self.mass_lbm, type=self.type)
if self.fracIsentropic == None:
summ.addAssumption( 'Integrate Blow-Down Temperatures')
elif self.fracIsentropic >= 1.0:
summ.addAssumption( 'Isentropic Blow-Down')
elif self.fracIsentropic <= 0.0:
summ.addAssumption( 'Iso-Thermal Blow-Down')
else:
summ.addAssumption( '%g%% Isentropic from Isothermal Blow-Down'%(100.0*self.fracIsentropic,))
if self.isBell:
summ.addAssumption( 'Bell Nozzle with Percent Bell = %g'%self.pcentBell)
else:
summ.addAssumption( 'Conical Nozzle with Half Angle = %g deg'%self.halfAngDeg )
# add inputs
if self.ItotGoal==None:
summ.addInput( 'Vbottle', self.Vbottle, 'cuin', '%g' )
else:
summ.addInput( 'ItotGoal', self.ItotGoal, 'lbf-sec', '%g' )
summ.addInput( 'dPregFinal', self.dPregFinal, 'psid', '%.3f' )
summ.addInput( 'MEOP', self.MEOP, 'psia', '%g' )
summ.addInput( 'PcRegulated', self.PcRegulated, 'psia', '%g' )
summ.addInput( 'ThrustAmb', self.ThrustAmb, 'lbf', '%.2f' )
summ.addInput( 'Pamb', self.Pamb, 'psia', '%g' )
summ.addInput( 'AreaRatio', self.AreaRatio, '', '%g' )
summ.addInput( 'TminR', self.TminR, 'degR', '%.1f' )
summ.addInput( 'TmaxR', self.TmaxR, 'degR', '%.1f' )
if type(self.fracIsentropic)==type(1.1):
summ.addInput( 'fracIsentropic', self.fracIsentropic, '', '%g' )
summ.addInput( 'gammaPolyMin', self.gammaPolyMin, '', '%g' )
# add outputs
if self.ItotGoal!=None:
summ.addOutput( 'Vbottle', self.Vbottle, 'cuin', '%g' )
summ.addOutput( 'PinitMin', self.PinitMin, 'psia', '%g' )
summ.addOutput( 'Pfinal', self.Pfinal, 'psia', '%g' )
summ.addOutput( 'WtGasLoaded', self.WtGasLoaded, 'lbm', '%g' )
summ.addOutput( 'WtGasExpelled', self.WtGasExpelled, 'lbm', '%g' )
summ.addOutput( 'densInit', self.densInit, 'lbm/cuft', '%g' )
summ.addOutput( 'densFinal', self.densFinal, 'lbm/cuft', '%g' )
summ.addOutput( 'WtMol',self.gasObj.WtMol,'lbm/lbmole','%.3f')
summ.addOutput( 'compressInit', self.compressInit, '(aka Z)', '%g' )
summ.addOutput( 'gammaIsen', self.gammaIsen, '', '%g' )
summ.addOutput( 'gammaPoly', self.gammaPoly, '', '%g' )
if self.fracIsentropicCalc:
summ.addOutput( 'fracIsentropic', self.fracIsentropicCalc, '', '%g' )
summ.addOutput( 'TfinalIsen', self.TfinalIsen, 'degR', '%.1f' )
summ.addOutput( 'TfinalGas', self.Tfinal, 'degR', '%.1f' )
summ.addOutput( 'TregInit', self.TregInit, 'degR', '%.1f' )
summ.addOutput( 'TregFinal', self.TregFinal, 'degR', '%.1f' )
summ.addOutput( 'TregAve', self.TregAve, 'degR', '%.1f' )
summ.addOutput( 'Cstar(@TregAve)', self.Cstar, 'ft/sec', '%.1f' )
summ.addOutput( 'At', self.At, 'sqin', '%g' )
summ.addOutput( 'wdot', self.wdot, 'lbm/sec', '%g' )
summ.addOutput( 'etaNoz', self.etaNoz, '', '%g' )
summ.addOutput( 'IspAmb(@TregAve)', self.IspAmb, 'sec', '%.1f' )
summ.addOutput( 'ItotVac', self.ItotVac, 'lbf-sec', '%g' )
summ.addOutput( '', '', '', '%s' )
self.gasObj.setTD(T=self.TminR,D=self.rhoLoaded*1728.0)
#summ.addOutput( 'Initial', self.gasObj.getStrTPD(), '', '%s' )
summ.addOutput( 'Initial', self.gasObj.Qdescription(), '', '%s' )
self.gasObj.setTD(T=self.Tfinal,D=self.rhoFinal*1728.0)
#summ.addOutput( 'Final', self.gasObj.getStrTPD(), '', '%s' )
summ.addOutput( 'Final', self.gasObj.Qdescription(), '', '%s' )
return summ
def reCalc(self):
self.gasObj.setTP(T=self.TmaxR,P=self.MEOP)
self.rhoLoaded = self.gasObj.rho
self.gasObj.setTD(T=self.TminR,D=self.rhoLoaded*1728.0)
self.PinitMin= self.gasObj.P
self.Pfinal = self.dPregFinal + self.PcRegulated
self.gammaIsen=self.gasObj.gamma()
self.compressInit = self.gasObj.compressibility()
#C CALCULATE POLYTROPIC GAMMA
WtMolGas = self.gasObj.WtMol
pratio = self.Pfinal / self.PinitMin
self.TfinalIsen = self.TminR*(pratio)**(1.-1./self.gammaIsen)
if self.etaNozInp==None:
if self.isBell:
isConical=0
else:
isConical=1
self.etaBL,self.etaDiv,self.etaKin, etaCf = \
Nozzle_Eff.calcNozzleEfficiency(Pc=self.PcRegulated, Fvac=self.ThrustAmb, eps=self.AreaRatio, At=None,
epsAtt=self.AreaRatio, isConical=isConical, pcentBell=self.pcentBell, halfAngleDeg=self.halfAngDeg,
iprop='coldgas', mr=1.0, etaKinInp=1.0,
adjBL=1.0, adjKin=1.0, adjDiv=1.0, isRegenCham=0, isRegenNoz=0 )
#print 'etaBL,etaDiv,etaKin',self.etaBL,self.etaDiv,self.etaKin
self.etaNoz = etaCf
else:
self.etaNoz = self.etaNozInp
if self.fracIsentropic==None:
if self.ItotGoal==None:
self.bottle = Bottle( name="Cold Gas Bottle", gasSymbol=self.symbol, tAction=self.tAction,
Pinit=self.PinitMin, Vbottle=self.Vbottle, Pfinal=self.Pfinal, Tinit=self.TminR, adiabatic=0,
AccGees=1.0, ellBottle=1.7, Nbottle=1,
MEOP=self.MEOP, LcylOvDBottle=1.0, PVoW_Bottle=500000., Cp_effBottle=0.15,
TbottleMatlConst=None, QexternalIntoBottle=0.0, PregOut=self.PcRegulated,
hcBottleInp=self.hcBottleInp)
else:
self.gasObj.setTP(T=self.TminR, P=self.Pfinal)
gam = self.gasObj.gamma()
IspEst = isp.calcidealis(gam,self.TminR,WtMolGas,self.AreaRatio,self.PcRegulated,self.Pamb)
TfEst = self.TfinalIsen
self.gasObj.setTP(T=TfEst, P=self.Pfinal)
rhoFinalEst = self.gasObj.rho
WtGasExpelledEst = self.ItotGoal / IspEst
VbottleEst = WtGasExpelledEst / (self.rhoLoaded-rhoFinalEst)
self.bottle = Bottle( name="Cold Gas Bottle", gasSymbol=self.symbol, tAction=self.tAction,
Pinit=self.PinitMin, Vbottle=VbottleEst, Pfinal=self.Pfinal, Tinit=self.TminR, adiabatic=0,
AccGees=1.0, ellBottle=1.7, Nbottle=1,
MEOP=self.MEOP, LcylOvDBottle=1.0, PVoW_Bottle=500000., Cp_effBottle=0.15,
TbottleMatlConst=None, QexternalIntoBottle=0.0, PregOut=self.PcRegulated,
hcBottleInp=self.hcBottleInp)
gammaPoly = self.bottle.gammaPoly
self.fracIsentropicCalc = (gammaPoly-self.gammaPolyMin) / (self.gammaIsen - self.gammaPolyMin)
else:
gammaPoly = self.gammaPolyMin + self.fracIsentropic * (self.gammaIsen - self.gammaPolyMin)
self.fracIsentropicCalc = None
#C FINAL PRESSURE
PF = self.Pfinal
#C ASSUME MINIMUM TEMPERATURE FOR INITIAL PRESSURE CONDITION
#c... Get starting pressure assuming minimum temperature
gammaExp=1.-1./gammaPoly
if gammaExp > 10.0:gammaExp=10.0
if gammaExp < -10.0:gammaExp=-10.0
self.Tfinal=self.TminR*(pratio)**gammaExp
self.gasObj.setTP(T=self.Tfinal,P=self.Pfinal)
self.rhoFinal = self.gasObj.rho
# make sure that final density is less than initial density
if self.rhoFinal >= self.rhoLoaded:
print 'WARNING in ColdGasACS, final density is >= initial density'
print ' Probably a phase change issue (see fluid properties in next line)'
print self.gasObj.getStrTPDphase()
self.rhoFinal = 0.999 * self.rhoLoaded
self.gasObj.setPD(P=self.Pfinal,D=self.rhoFinal*1728.0)
self.Tfinal=self.gasObj.T
self.densInit = 1728.0 * self.rhoLoaded
self.densFinal = 1728.0 * self.rhoFinal
self.gammaPoly = gammaPoly
# estimate regulator outlet temperature
self.gasObj.dup.setTP(T=self.TminR,P=self.PinitMin)
self.gasObj.dup.constH_newP( self.PcRegulated )
# ignore heat transfer, just use Joule Thomson effect
self.TregInit = self.gasObj.dup.T
self.gasObj.dup.setTP( T=self.Tfinal, P=self.Pfinal )
self.gasObj.dup.constH_newP( self.PcRegulated )
self.TregFinal = self.gasObj.dup.T
# now use average Treg outlet to calc Isp
self.TregAve = (self.TregInit + self.TregFinal) / 2.0
self.gasObj.setTP(T=self.TregAve, P=self.Pfinal)
gam = self.gasObj.gamma()
self.IspAmb = self.etaNoz * isp.calcidealis(gam,self.TregAve,WtMolGas,self.AreaRatio,self.PcRegulated,self.Pamb)
self.Cstar = isp.calccstar(gam,self.TregAve,WtMolGas)
self.wdot = self.ThrustAmb / self.IspAmb
self.At = self.wdot * self.Cstar / 32.174 / self.PcRegulated
if self.ItotGoal==None:
self.WtGasExpelled = self.Vbottle * (self.rhoLoaded-self.rhoFinal)
else:
self.WtGasExpelled = self.ItotGoal / self.IspAmb
self.Vbottle = self.WtGasExpelled / (self.rhoLoaded-self.rhoFinal)
self.WtGasLoaded = self.Vbottle * self.rhoLoaded
self.ItotVac = self.IspAmb * self.WtGasExpelled
self.mass_lbm = self.WtGasLoaded
if __name__ == "__main__": #self test
h = ColdGasACS(name="Cold Gas ACS",gasSymbol='HE', AreaRatio=10.,
MEOP=5000.,
Vbottle=862.0, PcRegulated=220.0, dPregFinal=120.,fracIsentropic=None,
TminR=505.0,TmaxR=550.0, ItotGoal=190.036)
print h.getMassStr()
print
print h.getSummary()
if h.bottle:
h.bottle.makeExcelPlots( title='')
if 0:
h = ColdGasACS(name="Nitrogen ACS",gasSymbol='HE',
Vbottle=6766.7*1.03*252./238., PcRegulated=109.0, dPregFinal=100.0,
TminR=510.0,TmaxR=550.0)
print h.getMassStr()
print
print h.getSummary()
|