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332 | # Applied Python PRISM
# (PRISM) PaRametrIc System Model
#
# Written by Charlie Taylor <cet@appliedpython.com>
# Oct,21 2005
from prism.MassItem import MassItem
from prism.isp.cea import CEA_Isp
from math import *
from prism.utils import Constants
from prism.Summary import Summary
from prism.props import Materials
from prism.isp import Nozzle_Eff
from prism.utils import mensuration
from prism.engines import ValveSolenoid
#from prism.props.refprop7.n23_fluid import n_fluid
from prism.props.refprop7.n_dll_fluid import n_fluid
from prism.pov import POV_Items, POV_Basics
class Engine_GasGas( MassItem ):
def __init__(self, name="engine", mass_lbm=0.0, oxName='O2', fuelName='CH4',
cxw=1.25, Pc=150.0, Fvac=100.0, eps=50.0, mr=2.5, CR=2.5, LoverDt=4.0, LchamMin=1.5,
etaERE=0.97, etaNoz=0.99,
matlInj="SS", cxwInj=1.0, cxwValves=1.0,
matlCham="Cb103(2250F)", cxwCham=1.0,
isBell=1, pcentBell=80.0, WtIgnAssy=6.0,
halfAngDeg=15.0, useFastCEALookup=0, Number=1, etaKinInp=1.0,
calcEtaNoz=1, thkChamMin=0.2, thkNozMin=0.02, matlNoz="Cb103", minBipropValveWt=0.2):
MassItem.__init__(self, name, type="inert")
self.Number = Number # number of engines
self.oxName = oxName
self.fuelName = fuelName
self.iprop = oxName + '/' + fuelName
self.Fvac = Fvac
self.Pc = Pc
self.eps = eps
self.mr = mr
self.CR = CR
self.LoverDt = LoverDt
self.LchamMin = LchamMin
self.cxw = cxw
self.cxwValves = cxwValves
self.minBipropValveWt = minBipropValveWt
self.etaERE = etaERE
self.etaKinInp = etaKinInp
self.WtIgnAssy = WtIgnAssy
self.isBell = isBell
self.pcentBell = pcentBell
self.halfAngDeg = halfAngDeg
self.etaNoz = etaNoz
self.calcEtaNoz = calcEtaNoz
self.matlInj = matlInj
self.thkNozMin = thkNozMin
self.thkChamMin = thkChamMin
self.cxwInj = cxwInj
self.rhoInj, self.syInj, self.eInj, tmingInj = Materials.getMatlProps(matlInj)
self.matlCham = matlCham
self.cxwCham = cxwCham
self.rhoCham, self.syCham, self.eCham, tmingCham = Materials.getMatlProps(matlCham)
self.matlNoz = matlNoz
self.rhoNoz, self.syNoz, self.eNoz, self.tmingNoz = Materials.getMatlProps(matlNoz)
# make gas property objects
self.FlObj = n_fluid(fuelName)
self.OxObj = n_fluid(oxName)
# assume identical ox and fuel valves
self.Valves = ValveSolenoid.ValveSolenoid( name='biprop valves',
Number=2, cxw=cxwValves, isGas=1 )
self.ispObj = CEA_Isp.CEA_Isp( oxName=oxName+'(G)', fuelName=fuelName+'(G)', useFastLookup=useFastCEALookup ) # create isp calculating object
self.reCalc()
def getPOV_Item(self):
# be sure to include pov_h, pov_w, and pov_d calcs in reCalc
if hasattr( self, 'texture'):
texture = self.texture
else:
texture = POV_Basics.Texture( colorName="Coral" )
s = POV_Items.TCA_Bell( xlc=self.Lcham*2./3. , xln=self.Lcham/3., CR=self.CR,
Rt=self.Dt/2., eps=self.eps, pcentBell=self.pcentBell, texture=texture)
return s
def reCalc(self, autoCalc=1):
self.autoCalc = autoCalc
# set design variables
self.IspODE,self.CstarODE,self.Tc = \
self.ispObj.get_IvacCstrTc(Pc=self.Pc, MR=self.mr, eps=self.eps)
if self.calcEtaNoz:
if self.isBell:
isConical=0
else:
isConical=1
self.etaBL,self.etaDiv,self.etaKin, etaCf = \
Nozzle_Eff.calcNozzleEfficiency(Pc=self.Pc, Fvac=self.Fvac, eps=self.eps,
epsAtt=self.eps, isConical=isConical, pcentBell=self.pcentBell, halfAngleDeg=self.halfAngDeg,
iprop=self.iprop, mr=self.mr, etaKinInp=self.etaKinInp,
adjBL=1.0, adjKin=1.0, adjDiv=1.0, isRegenCham=0, isRegenNoz=0 )
self.etaNoz = etaCf
self.effIsp = self.etaERE * self.etaNoz
self.Isp = self.IspODE * self.effIsp
self.Cstar = self.CstarODE * self.etaERE
self.wdotTot = self.Fvac / self.Isp
self.wdotOx = self.wdotTot * self.mr / (1.0 + self.mr)
self.wdotFl = self.wdotTot - self.wdotOx
self.OxObj.setTP( 530.0, self.Pc )
self.FlObj.setTP( 530.0, self.Pc )
self.volDotOx = self.wdotOx / self.OxObj.rho
self.volDotFl = self.wdotFl / self.FlObj.rho
self.Valves.cuInchPerSec = max( self.volDotOx, self.volDotFl )
self.Valves.reCalc()
self.WtValves = self.Valves.mass_lbm
ftPerSec = 30.0 # through valve
dCharFl = sqrt( 4.0 * self.volDotFl/ pi / ftPerSec)
dCharOx = sqrt( 4.0 * self.volDotOx / pi / ftPerSec)
self.dChar = max( dCharFl, dCharOx)
# weight of two identical valves
#self.WtValves = 2.0 * 0.268 * (self.dChar/1.279)**2
#if self.WtValves < self.minBipropValveWt: # minimum of 45 (0.2 lbm) grams per valve (90 total)
# self.WtValves = self.minBipropValveWt
#self.WtValves *= self.cxwValves
self.WtMisc = 0.319 * (self.dChar/1.279)**2 # scale miscellaneous like valve
if self.WtMisc < 0.1:
self.WtMisc = 0.1
self.At = self.Cstar* self.wdotTot / self.Pc / Constants.gc
self.Dt = sqrt( self.At / pi ) * 2.0
self.Dcham = self.Dt * sqrt( self.CR )
self.Lcham = self.Dt * self.LoverDt
if self.Lcham < self.LchamMin:
self.Lcham = self.LchamMin
self.Dexit = self.Dt * sqrt( self.eps )
if self.isBell:
self.Lnoz = (sqrt(self.eps)-1.0)*self.pcentBell*(self.Dt/2.0)/100.0/tan(15.0*pi/180.0)
# curve fit of ratio to minimum length rao nozzle
self.ratmlr = (self.pcentBell/100.0) * 1612.1/(self.eps + 1009.0)
self.SAnoz = self.Dt**2/4.*(3.368*(self.eps+10.875)**1.2606 + \
self.eps*(self.ratmlr-1.25)*10.75)
else:
self.Lnoz = (sqrt(self.eps)-1.0)*(self.Dt/2.0)/tan(self.halfAngDeg*pi/180.0)
r1 = self.Dt/2.0
r2 = self.Dexit/2.0
self.SAnoz = pi * sqrt((r1-r2)**2 + self.Lnoz**2) * (r1+r2)
#self.thkCham = 0.06 * (self.Pc/1000.0) * (self.Dcham/1.48)
self.thkCham = self.Pc * self.Dcham / self.syCham # SF=2 by using D instead of R
if self.thkCham < self.thkChamMin:
self.thkCham = self.thkChamMin
self.thkNoz = (self.thkCham*0.9 + 3.5*self.tmingNoz) / 4.5
if self.thkNoz < self.thkNozMin:
self.thkNoz = self.thkNozMin
self.WtNoz = self.thkNoz * self.SAnoz * self.rhoNoz
VolChamber = mensuration.cylVol( self.thkCham, self.Dcham, self.Lcham/2.0 ) + \
mensuration.coneVol( self.thkCham, self.Dcham, self.Dt, self.Lcham/2.0 )
self.WtChamber = VolChamber * self.rhoNoz # chamber is made of same matl as nozzle
thkMultAcc = 0.05 + 0.25/self.Dcham
VolAccustic = mensuration.cylVol( thkMultAcc*self.Dcham, self.Dcham, self.Lcham/2.0 )
self.WtAccustic = VolAccustic * self.rhoNoz
# the injector ht also gets smaller with increased Dcham
htMultDCham = min(1.0, 1.5/self.Dcham) * 2.0 # factor of 2.0 is for gas volume
htInj = self.Dcham*htMultDCham
VolInj = mensuration.solidCylVol( self.Dcham*1.1 , htInj )
self.WtInj = self.rhoInj * VolInj * self.cxwInj
self.Lengine = self.Lnoz + self.Lcham + self.Dcham # use Dcham as an inj face fwd length
# assume that the engine is submerged and insulated
VinsExt = mensuration.solidFrustrumVol( self.Dcham+.1, self.Dexit+.1, self.Lengine )
VinsExt = VinsExt - mensuration.solidFrustrumVol( self.Dt, self.Dexit, self.Lnoz ) \
- mensuration.solidFrustrumVol( self.Dt, self.Dcham, self.Lcham )
self.WtInsulation = VinsExt * 0.006
# add up parts
self.mass_lbm = self.WtNoz + self.WtChamber + self.WtInj + self.WtAccustic + \
self.WtMisc + self.WtInsulation + self.WtIgnAssy
self.mass_lbm = self.Number * ( self.mass_lbm * self.cxw + self.WtValves )
self.FtoW = self.Fvac * self.Number / self.mass_lbm
def buildSummary(self):
summList = []
summ = Summary( summName='Bipropellant Engine',
componentName=self.name, mass_lbm=self.mass_lbm, type=self.type)
summ.addAssumption( 'Propellants : ' + self.oxName + ' / ' + self.fuelName )
summ.addAssumption( 'NASA CEA Code for ODE performance ')
summ.addAssumption( 'Physical Weight Model ')
summ.addAssumption( 'Injector Material is ' + self.matlInj)
summ.addAssumption( 'Nozzle Material is ' + self.matlNoz)
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 )
if self.Number>1:
summ.addAssumption( 'Mass is for %i engines total'%self.Number )
summ.addAssumption( self.FlObj.getStrTPDphase() )
summ.addAssumption( self.OxObj.getStrTPDphase() )
#summ.addInput(self, label='generic param', value=0.0, units='', format='%g')
summ.addInput('Fvac', self.Fvac, 'lbf', '%g')
summ.addInput('Pc', self.Pc, 'psia', '%.1f')
summ.addInput('eps', self.eps, '', '%g')
if self.isBell:
summ.addInput('%Bell', self.pcentBell, '%', '%.2f')
else:
summ.addInput('halfAngDeg', self.halfAngDeg, 'deg', '%.2f')
summ.addInput('mr', self.mr, '', '%g')
summ.addInput('CR', self.CR, '', '%g')
summ.addInput('LoverDt', self.LoverDt, '', '%g')
summ.addInput('LchamMin',self.LchamMin, 'in', '%.3f')
summ.addInput('cxwInj', self.cxwInj, '', '%g')
summ.addInput('cxwValves', self.cxwValves, '', '%g')
summ.addInput('cxw', self.cxw, '', '%g')
summ.addInput('etaERE', self.etaERE, '', '%g')
if not self.calcEtaNoz:
summ.addInput('etaNoz', self.etaNoz, '', '%g')
# outputs
summ.addOutput('Isp', self.Isp, 'sec', '%g')
summ.addOutput('Cstar', self.Cstar, 'ft/sec', '%.1f')
if self.calcEtaNoz:
summ.addOutput('etaBL', self.etaBL, '', '%g')
summ.addOutput('etaDiv', self.etaDiv, '', '%g')
summ.addOutput('etaKin', self.etaKin, '', '%g')
summ.addOutput('etaNoz', self.etaNoz, '', '%g')
summ.addOutput('effIsp', self.effIsp, '', '%g')
summ.addOutput('IspODE', self.IspODE, 'sec', '%g')
summ.addOutput('CstarODE', self.CstarODE, 'ft/sec', '%.1f')
summ.addOutput('Tc', self.Tc, 'degR', '%.1f')
summ.addOutput('wdotTot', self.wdotTot, 'lbm/sec', '%g')
summ.addOutput('wdotOx ', self.wdotOx , 'lbm/sec', '%g')
summ.addOutput('wdotFl', self.wdotFl, 'lbm/sec', '%g')
summ.addOutput('rhoFl', self.FlObj.rho, 'lbm/cuin', '%.4f')
summ.addOutput('rhoOx', self.OxObj.rho, 'lbm/cuin', '%.4f')
summ.addOutput('volDotOx ', self.volDotOx , 'cuin/sec', '%g')
summ.addOutput('volDotFl', self.volDotFl, 'cuin/sec', '%g')
summ.addOutput('DFlow',self.dChar,'in','%.3f')
summ.addOutput('At', self.At, 'sqin', '%g')
summ.addOutput('Dt', self.Dt, 'in', '%.3f')
summ.addOutput('Dcham', self.Dcham, 'in', '%.3f')
summ.addOutput('Dexit', self.Dexit, 'in', '%.3f')
summ.addOutput('Lcham', self.Lcham, 'in', '%.3f')
summ.addOutput('Lnoz', self.Lnoz, 'in', '%.3f')
summ.addOutput('Lengine', self.Lengine, 'in', '%.3f')
summ.addOutput('rhoInj', self.rhoInj, 'lbm/cuin', '%.3f')
summ.addOutput('rhoNoz', self.rhoNoz, 'lbm/cuin', '%.3f')
summ.addOutput('thkCham', self.thkCham, 'in', '%.3f')
summ.addOutput('thkNoz', self.thkNoz, 'in', '%.3f')
summ.addOutput('WtNoz', self.WtNoz, 'lbm', '%.3f')
summ.addOutput('WtChamber', self.WtChamber, 'lbm', '%.3f')
summ.addOutput('WtInj', self.WtInj, 'lbm', '%.3f')
summ.addOutput('WtAccustic',self.WtAccustic, 'lbm', '%.3f')
summ.addOutput('WtValves(2)',self.WtValves, 'lbm', '%.3f')
summ.addOutput('WtMisc',self.WtMisc, 'lbm', '%.3f')
summ.addOutput('WtInsulation',self.WtInsulation,'lbm', '%.3f')
summ.addOutput('WtIgnAssy',self.WtIgnAssy,'lbm', '%.3f')
if self.Number>1:
summ.addOutput( 'wt/Engine', self.mass_lbm/self.Number, 'lbm', '%.3f' )
summ.addOutput('F/W', self.Number * self.Fvac/self.mass_lbm, 'lbf/lbm', '%.3f')
else:
summ.addOutput('F/W', self.Fvac/self.mass_lbm, 'lbf/lbm', '%.3f')
summList.append( summ )
# ======== now valves
summList.append( self.Valves.buildSummary() )
return summList
if __name__ == "__main__": #self test
print "Ponzo Proposal Engine =", 2.071,"lbm (1.815 w/o valves)"
h = Engine_GasGas(name="Ref Axial Engine", mass_lbm=0.0, oxName='O2', fuelName='CH4',
cxw=1.27, Pc=200.0, Fvac=100.0, eps=25.0, mr=2.5, CR=2.5, LoverDt=1.2,
etaERE=0.9, etaNoz=0.97, matlInj="SS", cxwInj=1.0, isBell=1, pcentBell=84.58, etaKinInp=.98,
halfAngDeg=15.0, useFastCEALookup=0, Number=1, calcEtaNoz=1, matlNoz="Cb103")
print "Calculated = ",h.getMassStr()
print "w/o valves= %.3f lbm"%(h.mass_lbm - h.WtValves,)
print
print h.getSummary()
print
|