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from math import pi, sqrt, atan 

 

from rocketprops.rocket_prop import get_prop 

from rocketprops.unit_conv_data import get_value # for any units conversions 

from rocketisp.efficiency.calc_noz_kinetics import calc_IspODK 

from rocketisp.efficiency.eff_vaporization import calc_C1_C2, fracVaporized 

 

# acoustic mode multipliers 

modeSvnD = {'1T':1.8413,'2T':3.0543,'1R':3.8317,'3T':4.2012,'4T':5.3175, 

'1T1R':5.3313,'2T1R':6.7060,'2R':7.0156,'3T1R':8.0151,'1T2R':8.5263} 

 

 

class Injector: 

""" 

Injector object holds basic information about the injector. 

Injector design features are calculated 

including chamber losses due to the injector, Em, Mix and Vap. 

 

:param coreObj: CoreStream object  

:param Tox: degR, temperature of oxidizer 

:param Tfuel: degR, temperature of fuel 

:param Em: intra-element Rupe mixing factor 

:param fdPinjOx: fraction of Pc used as oxidizer injector pressure drop 

:param fdPinjFuel: fraction of Pc used as fuel injector pressure drop 

:param dpOxInp: input value of injector pressure drop for oxidizer (overrides fdPinjOx) 

:param dpFuelInp: input value of injector pressure drop for fuel (overrides fdPinjFuel) 

:param setNelementsBy: flag determines how to calculate number of elements ( "acoustics", "elem_density", "input") 

:param elemDensInp: elem/in**2, input value for element density (setNelementsBy == "elem_density") 

:param NelementsInp: input value for number of elements (setNelementsBy == "input") 

:param OxOrfPerEl: number of oxidizer orifices per element 

:param FuelOrfPerEl: number of fuel orifices per element 

:param lolFuelElem: flag for like-on-like fuel element (determines strouhal multiplier) 

:param setAcousticFreqBy: flag indicating how to determine design frequency. (can be "mode" or "freq") 

:param desAcousMode: driving acoustic mode of injector OR acoustic mode multiplier (setNelementsBy=="acoustics" and setAcousticFreqBy=="mode") 

:param desFreqInp: Hz, driving acoustic frequency of injector (sets D/V if setNelementsBy=="acoustics" and setAcousticFreqBy=="freq") 

 

:param CdOxOrf: flow coefficient of oxidizer orifices 

:param CdFuelOrf: flow coefficient of fuel orifices 

:param dropCorrOx: oxidizer drop size multiplier 

:param dropCorrFuel: fuel drop size multiplier 

:param DorfMin: in, minimum orifice diameter (lower limit) 

:param LfanOvDorfOx: fan length / oxidizer orifice diameter 

:param LfanOvDorfFuel: fan length / fuel orifice diameter 

:type coreObj: CoreStream 

:type Tox: float 

:type Tfuel: float 

:type Em: float 

:type fdPinjOx: float 

:type fdPinjFuel: float 

:type dpOxInp: None or float 

:type dpFuelInp: None or float 

:type setNelementsBy: str 

:type elemDensInp: float 

:type NelementsInp: float 

:type OxOrfPerEl: float 

:type FuelOrfPerEl: float 

:type lolFuelElem: bool 

:type setAcousticFreqBy: str 

:type desAcousMode: str or float 

:type desFreqInp: None or float 

:type CdOxOrf: float 

:type CdFuelOrf: float 

:type dropCorrOx: float 

:type dropCorrFuel: float 

:type DorfMin: float 

:type LfanOvDorfOx: float 

:type LfanOvDorfFuel: float 

:return: Injector object 

:rtype: Injector  

""" 

 

def __init__(self, coreObj, # CoreStream object 

Tox=None, Tfuel=None, Em=0.8, 

fdPinjOx=0.25, fdPinjFuel=0.25, dpOxInp=None, dpFuelInp=None, 

setNelementsBy='acoustics', # can be "acoustics", "elem_density", "input" 

elemDensInp=5, NelementsInp=100, 

OxOrfPerEl=1.0, FuelOrfPerEl=1.0, 

lolFuelElem=True, 

setAcousticFreqBy='mode', # can be "mode" or "freq" 

desAcousMode='3T', desFreqInp=5000, 

CdOxOrf=0.75, CdFuelOrf=0.75, dropCorrOx=0.33, dropCorrFuel=0.33, 

DorfMin=0.008, 

LfanOvDorfOx=20.0, LfanOvDorfFuel=20.0): 

""" 

Injector object holds basic information about the injector. 

Injector design features are calculated 

including chamber losses due to the injector, Em, Mix and Vap. 

""" 

self.coreObj = coreObj 

self.geomObj = coreObj.geomObj 

self.ceaObj = coreObj.ceaObj 

 

# build propellant objects 

self.oxProp = pObj = get_prop( self.coreObj.oxName ) 

self.fuelProp = pObj = get_prop( self.coreObj.fuelName ) 

 

if Tox is None: Tox = min(530.0, self.oxProp.Tnbp) 

self.Tox = Tox 

if Tfuel is None: Tfuel = min(530.0, self.fuelProp.Tnbp) 

self.Tfuel = Tfuel 

 

self.Em = min(1.0, Em) # intra-element mixing parameter for injector 

self.fdPinjOx = fdPinjOx 

self.fdPinjFuel = fdPinjFuel 

self.dpOxInp = dpOxInp 

self.dpFuelInp = dpFuelInp 

self.setNelementsBy = setNelementsBy.lower() # just in case user screw up. 

 

self.elemDensInp = elemDensInp 

self.NelementsInp = NelementsInp 

self.OxOrfPerEl = OxOrfPerEl 

self.FuelOrfPerEl = FuelOrfPerEl 

 

self.lolFuelElem = lolFuelElem 

if lolFuelElem: 

self.strouhal_mult = 0.1 # LOL element uses 0.1 strouhal multiplier 

else: 

self.strouhal_mult = 0.2 # unlike element uses 0.2 strouhal multiplier 

 

self.desAcousMode = desAcousMode 

if desAcousMode in modeSvnD: 

self.desAcousMult = modeSvnD[ desAcousMode ] 

else: 

self.desAcousMult = float( desAcousMode ) # let it raise exception if not a float 

self.desFreqInp = desFreqInp 

 

self.setAcousticFreqBy = setAcousticFreqBy.lower() # can be "mode" or "freq" 

 

self.CdOxOrf = CdOxOrf 

self.CdFuelOrf = CdFuelOrf 

self.dropCorrOx = dropCorrOx 

self.dropCorrFuel = dropCorrFuel 

self.DorfMin = DorfMin 

self.LfanOvDorfOx = LfanOvDorfOx 

self.LfanOvDorfFuel = LfanOvDorfFuel 

 

# get oxidizer propellant properties 

self.sgOx = self.oxProp.SG_compressed( Tox, self.coreObj.Pc ) # g/ml 

self.dHvapOx = self.oxProp.HvapAtTdegR( Tox ) # BTU/lbm 

self.surfOx = self.oxProp.SurfAtTdegR( Tox ) # lbf/in 

 

self.viscOx = self.oxProp.ViscAtTdegR( Tox ) # poise 

self.viscOx = get_value( self.viscOx, 'poise', 'lbm/s/ft') 

 

self.MolWtOx = self.oxProp.MolWt 

 

# get fuel propellant properties 

self.sgFuel = self.fuelProp.SG_compressed( Tfuel, self.coreObj.Pc ) # g/ml 

self.dHvapFuel = self.fuelProp.HvapAtTdegR( Tfuel ) # BTU/lbm 

self.surfFuel = self.fuelProp.SurfAtTdegR( Tfuel ) # lbf/in 

self.viscFuel = self.fuelProp.ViscAtTdegR( Tfuel ) # poise 

self.viscFuel = get_value( self.viscFuel, 'poise', 'lbm/s/ft') 

 

self.MolWtFuel = self.fuelProp.MolWt 

 

# --------- start vaporization calcs -------- 

self.rhoOx = rho = get_value( self.sgOx, 'SG', 'lbm/in**3' ) 

self.rhoFuel = rho = get_value( self.sgFuel, 'SG', 'lbm/in**3' ) 

 

self.calc_element_attr() # e.g. Nelements, injection velocities, elements diam, etc. 

#self.evaluate() 

 

def __call__(self, name): 

return getattr(self, name ) # let it raise exception if no name attr. 

 

def evaluate(self, DOREVAL=False): 

""" 

Calculates chamber losses due to the injector, Em, Mix and Vap. 

""" 

 

# recalc CoreStream in case a basic parameter has changed. 

self.coreObj.evaluate() 

 

self.calc_element_attr() # e.g. Nelements, injection velocities, elements diam, etc. 

 

effObj = self.coreObj.effObj 

 

# calc intra-element mixing efficiency and reset BasicThruster effEm 

#if self.calc_effEm: 

if not effObj['Em'].is_const: 

effEm = self.calculate_effEm() # calc intra-element mixing efficiency 

msg = 'Rupe Em=%g'%self.Em 

effObj.set_value( 'Em', effEm, value_src=msg, re_evaluate=DOREVAL) 

 

# calc inter-element mixing efficiency 

#if self.calc_effMix: 

if not effObj['Mix'].is_const: 

effMix = self.calculate_effMix() # calc inter-element mixing efficiency (2 deg estimate) 

msg = 'mixAngle=%.2f deg'%self.mixAngle 

effObj.set_value( 'Mix', effMix, value_src=msg, re_evaluate=DOREVAL) 

 

# vaporization efficiency 

#if self.calc_effVap: 

if not effObj['Vap'].is_const: 

effVap = self.calculate_effVap() 

msg = 'gen vaporized length' 

self.coreObj.effObj.set_value( 'Vap', effVap, value_src=msg, re_evaluate=DOREVAL) 

 

 

# recalc CoreStream in case a basic parameter has changed. 

# self.coreObj.evaluate() <-- handled by re_evaluate flags 

 

 

def calculate_effVap(self): 

"""calculate vaporization efficiency""" 

self.C1fuel, self.C2fuel = calc_C1_C2(self.fuelProp, self.Tfuel, self.rhoFuel, self.dHvapFuel, 

self.surfFuel, self.viscFuel, self.MolWtFuel) 

#print('C1fuel=%g, C2fuel=%g'%(self.C1fuel, self.C2fuel) ) 

 

self.C1ox, self.C2ox = calc_C1_C2(self.oxProp, self.Tox, self.rhoOx, self.dHvapOx, 

self.surfOx, self.viscOx, self.MolWtOx) 

#print('C1ox=%g, C2ox=%g'%(self.C1ox, self.C2ox) ) 

 

# now figure out dropo sizes 

#C MEDIAN DROPLET RADIUS 

self.rDropOx = 0.05 * self.DorfOx * self.C1ox * self.dropCorrOx 

self.rDropFuel = 0.05 * self.DorfFuel * self.C1fuel * self.dropCorrFuel 

 

CR = self.geomObj.CR 

#C CHAMBER SHAPE FACTOR 

self.ShapeFact = (1.0 + 1.0/sqrt(CR) + 1./ CR )/3. 

 

# GENERALIZED VAPORIZATION LENGTH 

# Taken from Technical Report R-67, Propellant Vaporization as a Design Criterion 

# for Rocket-Engine Combustion Chambers by Richard J. Priem and Marcus F. Heidmann 

# see: https://digital.library.unt.edu/ark:/67531/metadc56386/ 

# or: https://www.google.com/books/edition/Propellant_Vaporization_as_a_Design_Crit/Jt4QAQAAIAAJ?hl=en&gbpv=1 

 

CFX = (self.geomObj.Lcham_cyl/CR**.44 + .83*self.geomObj.Lcham_conv/(CR**.22 * self.ShapeFact**.33))\ 

*(self.coreObj.Pc/300.)**.66 

self.genVapLenOx = CFX/(self.C2ox*(self.rDropOx/.003)**1.45 * (self.velOx_ips/1200.)**.75) 

self.genVapLenFuel = CFX/(self.C2fuel*(self.rDropFuel/.003)**1.45 * (self.velFuel_ips/1200.)**.75) 

 

self.fracVapOx = fracVaporized( self.genVapLenOx ) 

self.fracVapFuel = fracVaporized( self.genVapLenFuel ) 

 

 

# get vaporized MR 

self.mrVap = self.coreObj.MRcore * self.fracVapOx / self.fracVapFuel 

 

# get total vaporized propellant (ox + fuel) 

self.fracVapTot = (self.fracVapOx*self.coreObj.wdotOx + self.fracVapFuel*self.coreObj.wdotFl) / \ 

self.coreObj.wdotTot 

 

# calc vaporization efficiency (protect against excess fracVapTot) 

if self.fracVapTot < 1.0: 

vapIsp = self.ceaObj.get_Isp( Pc=self.coreObj.Pc, MR=self.mrVap, eps=self.geomObj.eps) 

effVap = min(1.0, self.fracVapTot * vapIsp / self.coreObj.IspODE) 

else: 

effVap = 1.0 

 

return effVap 

 

 

def calculate_effEm(self): 

"""calc intra-element mixing efficiency""" 

 

if self.Em >= 1.0: 

self.effEm = 1.0 

return 1.0 

 

mrLow = self.coreObj.MRcore * self.Em 

mrHi = self.coreObj.MRcore / self.Em 

 

IspODK = calc_IspODK(self.ceaObj, Pc=self.coreObj.Pc, eps=self.geomObj.eps, Rthrt=self.geomObj.Rthrt, 

pcentBell=self.geomObj.pcentBell, MR=self.coreObj.MRcore) 

 

odkLoIsp = calc_IspODK(self.ceaObj, Pc=self.coreObj.Pc, eps=self.geomObj.eps, Rthrt=self.geomObj.Rthrt, 

pcentBell=self.geomObj.pcentBell, MR=mrLow) 

odkHiIsp = calc_IspODK(self.ceaObj, Pc=self.coreObj.Pc, eps=self.geomObj.eps, Rthrt=self.geomObj.Rthrt, 

pcentBell=self.geomObj.pcentBell, MR=mrHi) 

 

xm1=(1.+mrLow)/(1.+self.Em)/(1.+self.coreObj.MRcore) 

xm2=1.0-xm1 

effEm = (xm1*odkLoIsp + xm2*odkHiIsp) / IspODK 

 

return max(effEm, 0.00001) 

 

def calculate_effMix(self): 

"""calc inter-element mixing efficiency""" 

DiamElem = self.geomObj.Dinj * sqrt(pi/4.0/self.Nelements) - (self.DorfOx+self.DorfFuel)/2.0 

DiamElem = max(DiamElem,0.0) 

self.mixAngle = atan( DiamElem / self.geomObj.Lcham )*(180.0/pi) 

effMix = 1. - .01*(self.mixAngle/2.)**2 

#print('DiamElem',DiamElem, ' effMix',effMix, ' mixAngle',self.mixAngle, ' L', self.geomObj.Lcham ) 

return max(effMix, 0.00001) 

 

def calc_element_attr(self): 

"""calc Nelements, injection velocities, elements diam, etc.""" 

 

if self.dpOxInp is None: 

self.dpOx = self.fdPinjOx * self.coreObj.Pc 

else: 

self.dpOx = self.dpOxInp 

self.fdPinjOx = self.dpOxInp / self.coreObj.Pc 

 

if self.dpFuelInp is None: 

self.dpFuel = self.fdPinjFuel * self.coreObj.Pc 

else: 

self.dpFuel = self.dpFuelInp 

self.fdPinjFuel = self.dpFuelInp / self.coreObj.Pc 

 

# calc chamber sonic velocity 

aODE = self.ceaObj.get_SonicVelocities(Pc=self.coreObj.Pc, 

MR=self.coreObj.MRcore, 

eps=self.geomObj.eps)[0] 

# estimate effective sonic velocity in chamber 

self.sonicVel = aODE * 0.9 

 

velFl_ips = sqrt( 24.0 * 32.174 * self.dpFuel / self.rhoFuel ) # in/sec 

 

 

# calc number of elements and element density 

if self.setNelementsBy == 'input': 

self.Nelements = self.NelementsInp 

self.NOxOrf = max( 1.0, self.Nelements * self.OxOrfPerEl) 

self.NFuelOrf = max( 1.0, self.Nelements * self.FuelOrfPerEl) 

self.elemDensCalc = self.Nelements / self.geomObj.Ainj 

 

elif self.setNelementsBy == 'acoustics': 

if self.setAcousticFreqBy == "mode": 

self.des_freq = self.desAcousMult * self.sonicVel / pi / (self.geomObj.Dinj/12.0) 

elif self.setAcousticFreqBy == "freq": 

self.des_freq = self.desFreqInp 

else: 

raise exception( 'setAcousticFreqBy = "%s", must be "mode" or "freq"'%self.setAcousticFreqBy ) 

 

self.DorfFlForHzLimit = self.strouhal_mult * velFl_ips / self.des_freq 

self.dOrifMin = max(self.DorfMin, self.DorfFlForHzLimit) 

 

wdotFlOrif = velFl_ips * self.rhoFuel * self.CdFuelOrf * self.dOrifMin**2 * pi / 4.0 

 

self.NFuelOrf = float(int( 0.5 + max(1.0, self.coreObj.wdotFl / wdotFlOrif))) 

self.Nelements = max(1.0, self.NFuelOrf / self.FuelOrfPerEl) 

self.NOxOrf = max( 1.0, self.Nelements * self.OxOrfPerEl) 

self.elemDensCalc = self.Nelements / self.geomObj.Ainj 

 

elif self.setNelementsBy == 'elem_density': 

self.Nelements =float(int( 0.5 + max( 1.0, self.elemDensInp * self.geomObj.Ainj ))) 

self.NOxOrf = max( 1.0, self.Nelements * self.OxOrfPerEl) 

self.NFuelOrf = max( 1.0, self.Nelements * self.FuelOrfPerEl) 

self.elemDensCalc = self.elemDensInp 

else: 

raise Exception('setNelementsBy="%s" must be "acoustics", "elem_density" or "input"'%self.setNelementsBy) 

 

 

gcc = 32.174 * 12.0 * 2.0 

PIO4 = pi / 4.0 

self.velOx_ips = sqrt(gcc*self.dpOx/self.rhoOx) # in/sec 

self.velFuel_ips = sqrt(gcc*self.dpFuel/self.rhoFuel) # in/sec 

self.AfloOx = self.coreObj.wdotOx/(self.rhoOx*self.CdOxOrf*self.velOx_ips) 

self.AfloFuel = self.coreObj.wdotFl/(self.rhoFuel*self.CdFuelOrf*self.velFuel_ips) 

self.DorfOx = sqrt(self.AfloOx/(PIO4*self.NOxOrf)) 

self.DorfFuel = sqrt(self.AfloFuel/(PIO4*self.NFuelOrf)) 

 

# calc (or recalc) des_freq based on actual fuel orifice 

self.des_freq = self.strouhal_mult * velFl_ips / self.DorfFuel 

 

self.velOx_fps = self.velOx_ips / 12.0 # convert from in/sec to ft/sec 

self.velFuel_fps = self.velFuel_ips / 12.0 # convert from in/sec to ft/sec 

 

# evaluate chug stability based on core stream properties 

mwODE,gamODE = self.coreObj.MWchm, self.coreObj.gammaChm 

cstarERE, TcombODE = self.coreObj.cstarERE, self.coreObj.TcODE 

 

self.tResid = cstarERE * self.geomObj.Vcham * mwODE / 18540.0 / TcombODE / self.geomObj.At / 32.174 

self.tauOx = self.LfanOvDorfOx * self.DorfOx / self.velOx_ips # vel is in/sec 

self.tauFuel = self.LfanOvDorfFuel * self.DorfFuel / self.velFuel_ips 

 

self.tauOvResOx = self.tauOx / self.tResid 

self.tauOvResFuel = self.tauFuel / self.tResid 

 

def reqd_dPinjOvPc( tauOvRes ): 

C1 = 1.0/(0.4961 + 0.4031/tauOvRes) 

C2 = 1.0/(0.25 + 0.009649*tauOvRes) 

return 1.0/(C1 + C2/tauOvRes) 

 

self.fdPinjOxReqd = reqd_dPinjOvPc( self.tauOvResOx ) 

self.fdPinjFuelReqd = reqd_dPinjOvPc( self.tauOvResFuel ) 

 

 

def summ_print(self, show_core_stream=True): 

""" 

print to standard output, the current state of Injector instance. 

""" 

 

if show_core_stream: 

self.coreObj.summ_print() 

 

 

# calc 3T and 1L for printout only 

f3T = modeSvnD['3T'] * self.sonicVel / pi / (self.geomObj.Dinj/12.0) 

freq1L = self.sonicVel * 12.0 / 2.0 / self.geomObj.Lcham 

 

 

print('---------------%s/%s injector-----------------------'%(self.coreObj.oxName, self.coreObj.fuelName)) 

 

print('NOTE: number of elements set by ', self.setNelementsBy) 

if self.setNelementsBy == "acoustics": 

if self.setAcousticFreqBy == "mode": 

if self.desAcousMode in modeSvnD: 

msg = self.desAcousMode + ' where: Svn mult = %g'%self.desAcousMult 

else: 

msg = 'Svn multiplier = %g'%self.desAcousMult 

elif self.setAcousticFreqBy == "freq": 

msg = 'freq=%g Hz'%self.desFreqInp 

 

print(' Acoustic frequency set by %s'%msg) 

elif self.setNelementsBy == "input": 

print(' Number of elements = %g'%self.NelementsInp) 

elif self.setNelementsBy == "elem_density": 

print(' Element Density = %g elem/in**2'%self.elemDensInp) 

 

if self.setNelementsBy == 'acoustics': 

mil = get_value(self.DorfFlForHzLimit,'inch','mil') 

 

if self.DorfFuel < self.DorfFlForHzLimit * 0.999: 

print( 'WARNING... Fuel Orifice is Less Than D/V Requirement of %.1f mil'%mil ) 

else: 

print( 'Fuel Orifice Meets Stability Requirement of >= %.1f mil'%mil ) 

 

if self.des_freq > f3T * 1.0001: 

print( 'WARNING... Design frequency is above recommended 3T limit of %i Hz'%int(f3T) ) 

 

if self.DorfOx < self.DorfMin * 0.999: 

mil = get_value(self.DorfMin,'inch','mil') 

print( 'WARNING... Oxidizer Orifice is Less Than minimum limit of %.1f mil'%mil ) 

 

if self.DorfFuel < self.DorfMin * 0.999: 

mil = get_value(self.DorfMin,'inch','mil') 

print( 'WARNING... Fuel Orifice is Less Than minimum limit of %.1f mil'%mil ) 

 

print('-------------------------------------------------------') 

 

 

 

print(' Tox =', '%g'%self.Tox, 'degR, temperature of oxidizer') 

print(' Tfuel =', '%g'%self.Tfuel, 'degR, temperature of fuel') 

print(' Em =', '%s'%self.Em, 'Rupe factor of injector') 

 

if self.dpOxInp is None: 

print(' fdPinjOx =', '%g'%self.fdPinjOx, '(dpOx=%.1f psia)'%self.dpOx) 

else: 

print(' dpOxInp =', '%.1f psia'%self.dpOxInp, '(fdPinjOx=%g)'%self.fdPinjOx) 

 

if self.dpFuelInp is None: 

print(' fdPinjFuel =', '%g'%self.fdPinjFuel, '(dpFuel=%.1f psia)'%self.dpFuel) 

else: 

print(' dpFuelInp =', '%.1f psia'%self.dpFuelInp, '(fdPinjFuel=%g)'%self.fdPinjFuel) 

 

print(' OxOrfPerEl =', '%g'%self.OxOrfPerEl, '') 

print(' FuelOrfPerEl =', '%g'%self.FuelOrfPerEl, '') 

print(' lolFuelElem =', '%s'%self.lolFuelElem, '') 

 

if self.desFreqInp is None: 

print(' desAcousMode =', '%s'%self.desAcousMode, '(Sv mult=%g)'%self.desAcousMult) 

else: 

print(' desFreqInp =', '%g'%self.desFreqInp, 'Hz') 

 

print(' CdOxOrf =', '%g'%self.CdOxOrf, '') 

print(' CdFuelOrf =', '%g'%self.CdFuelOrf, '') 

print(' dropCorrOx =', '%g'%self.dropCorrOx, '') 

print(' dropCorrFuel =', '%g'%self.dropCorrFuel, '') 

print(' DorfMin =', '%g'%self.DorfMin, 'in') 

print(' LfanOvDorfOx =', '%g'%self.LfanOvDorfOx, '') 

print('LfanOvDorfFuel =', '%g'%self.LfanOvDorfFuel, '') 

print() 

print(' sgOx =', '%g'%self.sgOx, 'g/ml') 

print(' dHvapOx =', '%g'%self.dHvapOx, 'BTU/lbm') 

print(' surfOx =', '%g'%self.surfOx, 'lbf/in') 

print(' viscOx =', '%g'%self.viscOx, 'poise') 

print(' MolWtOx =', '%g'%self.MolWtOx, 'g/gmole') 

print() 

print(' sgFuel =', '%g'%self.sgFuel, 'g/ml') 

print(' dHvapFuel =', '%g'%self.dHvapFuel, 'BTU/lbm') 

print(' surfFuel =', '%g'%self.surfFuel, 'lbf/in') 

print(' viscFuel =', '%g'%self.viscFuel, 'poise') 

print(' MolWtFuel =', '%g'%self.MolWtFuel, 'g/gmole') 

print(' cham sonicVel =', '%g'%self.sonicVel, 'ft/sec') 

print() 

print(' dpOx =', '%g'%self.dpOx, 'psid') 

print(' dpFuel =', '%g'%self.dpFuel, 'psid') 

 

 

print(' cham des_freq =', '%g'%int(self.des_freq), 'Hz (NOTE: 3T = %g Hz)'%int(f3T)) 

 

if self.setNelementsBy == "acoustics": 

print('DorfFlForHzLim =', '%.4f'%self.DorfFlForHzLimit, 'in, fuel orifice D for frequency in Hewitt Corr.') 

print(' dOrifMin =', '%.4f'%self.dOrifMin, 'in, min Dorifice allowed by stability & manufacturing') 

 

print(' Nelements =', '%g'%self.Nelements, '(set by %s)'%self.setNelementsBy) 

print(' NFuelOrf =', '%g'%self.NFuelOrf, '') 

print(' NOxOrf =', '%g'%self.NOxOrf, '') 

print(' elemDens =', '%g'%self.elemDensCalc, 'elem/in**2') 

 

print(' velOx =', '%g'%self.velOx_fps, 'ft/sec') 

print(' velFuel =', '%g'%self.velFuel_fps, 'ft/sec') 

print(' AfloOx =', '%g'%self.AfloOx, 'in**2') 

print(' AfloFuel =', '%g'%self.AfloFuel, 'in**2') 

print(' DorfOx =', '%.4f'%self.DorfOx, 'in') 

print(' DorfFuel =', '%.4f'%self.DorfFuel, 'in') 

 

 

#if self.calc_effVap: 

if hasattr(self, 'rDropOx'): 

# only print internal vaporization values if calc'd 

print(' ---') 

print(' rDropOx =', '%g'%get_value(self.rDropOx,'inch','mil'), 'mil, median ox droplet radius') 

print(' rDropFuel =', '%g'%get_value(self.rDropFuel,'inch','mil'), 'mil, median fuel droplet radius') 

 

print(' chamShapeFact =', '%g'%self.ShapeFact, '') 

 

print(' genVapLenOx =', '%g'%self.genVapLenOx, '') 

print(' genVapLenFuel =', '%g'%self.genVapLenFuel, '') 

print(' fracVapOx =', '%g'%self.fracVapOx, '') 

print(' fracVapFuel =', '%g'%self.fracVapFuel, '') 

 

print(' mrVap =', '%g'%self.mrVap, 'vaporized mixture ratio') 

 

 

print(' ---') 

print(' tResid =', '%g'%(self.tResid*1000.0,) , 'ms, residual time in chamber') 

print(' tauOx =', '%g'%(self.tauOx*1000.0,) , 'ms, oxidizer lag time (tau/tResid=%g)'%self.tauOvResOx) 

print(' tauFuel =', '%g'%(self.tauFuel*1000.0,) , 'ms, fuel lag time (tau/tResid=%g)'%self.tauOvResFuel) 

print(' fdPinjOxReqd =', '%g'%self.fdPinjOxReqd, 'required oxidizer dP/Pc') 

print('fdPinjFuelReqd =', '%g'%self.fdPinjFuelReqd, 'required fuel dP/Pc') 

 

 

print(' --- Acoustic Modes in Chamber ---') 

modeL = [(freq1L,'1L')] # list of (freq, name) 

 

modeL.append( ( 0.8 * modeSvnD['1T'] * self.sonicVel / pi / (self.geomObj.Dinj/12.0), '80% of 1T') ) 

modeL.append( ( 0.8 * modeSvnD['1R'] * self.sonicVel / pi / (self.geomObj.Dinj/12.0), '80% of 1R') ) 

modeL.append( ( 0.8 * modeSvnD['3T'] * self.sonicVel / pi / (self.geomObj.Dinj/12.0), '80% of 3T') ) 

modeL.append( ( 0.999999 * modeSvnD['3T'] * self.sonicVel / pi / (self.geomObj.Dinj/12.0), ' 3T') ) 

 

modeL.append( (self.des_freq, '=====> DESIGN') ) 

 

for name, mult in modeSvnD.items(): 

modeL.append( (mult * self.sonicVel / pi / (self.geomObj.Dinj/12.0), name) ) 

modeL.sort() 

for (freq, name) in modeL: 

comment = modeCommentD.get( name, '') 

print(' %10s ='%name, '%i'%int(freq), 'Hz '+comment) 

 

#print(' xxx =', '%g'%self.xxx, 'xxx') 

modeCommentD = {'80% of 1T':'no damping required here', 

'80% of 1R':'baffles-only work here', 

'3T':'<== MAX FREQUENCY... KEEP Hz HERE OR BELOW', 

'80% of 3T':'cavities-only work here', 

'=====> DESIGN':'<== DESIGN IS HERE', 

' 3T':'baffles + cavities OR multi-tuned cavities'} 

 

 

 

if __name__ == '__main__': 

from rocketisp.geometry import Geometry 

from rocketisp.stream_tubes import CoreStream 

from rocketisp.efficiencies import Efficiencies 

 

geomObj = Geometry(Rthrt=5.868/2, 

CR=2.5, eps=150, pcentBell=80, 

RupThroat=1.5, RdwnThroat=1.0, RchmConv=1.0, cham_conv_deg=30, 

LchmOvrDt=3.10, LchmMin=2.0, LchamberInp=16) 

 

effObj = Efficiencies() 

#effObj.set_const('ERE', 0.98) 

 

core = CoreStream( geomObj, effObj, oxName='N2O4', fuelName='MMH', MRcore=1.85, 

Pc=150, CdThroat=0.995, 

pcentFFC=14.0, ko=0.035) 

 

I = Injector(core, Em=0.8, fdPinjOx=0.3, fdPinjFuel=0.3, elemDensInp=7.0, NelementsInp=676, 

setNelementsBy='elem_density', # can be "acoustics", "elem_density", "input" 

desFreqInp=2000, 

setAcousticFreqBy='mode', desAcousMode='2T') 

I.evaluate() 

I.summ_print()