class PerfInjThruster:
def __init__(self, name='PI Thruster', geomObj=Geometry(), ERE=0.98,
oxName='N2O4', fuelName='MMH', MRcore=1.9, Pc=500,
isRegenCham=0, noz_regen_eps=1.0, calc_CdThroat=True):
# create a perfect injector CoreStream
coreObj = CoreStream( geomObj=geomObj,
effObj=Efficiencies(ERE=ERE),
oxName=oxName, fuelName=fuelName,
MRcore=MRcore, Pc=Pc)
self.R = RocketThruster( name=name,
coreObj=coreObj, injObj=None,
isRegenCham=isRegenCham, noz_regen_eps=noz_regen_eps,
calc_CdThroat=calc_CdThroat)
def summ_print(self):
self.R.summ_print()
def scale_Rt_to_Thrust(self, ThrustLbf=500.0, Pamb=0.0, use_scipy=False):
"""
Adjust throat size in order to get total thrust at specified ambient pressure exactly
:param ThrustLbf: lbf, desired thrust at specified ambient pressure (Pamb)
:param Pamb: psia, ambient pressure
:param use_scipy: flag to indicate the need for more sophisticated root finder
:type ThrustLbf: float
:type Pamb: float
:type use_scipy: bool
:return: None
:rtype: None """
self.R.scale_Rt_to_Thrust( ThrustLbf=ThrustLbf, Pamb=Pamb, use_scipy=use_scipy )
def set_to_optimum_MR(self):
"""Starting with MR for ER=1 find max Isp MR"""
C = self.R.coreObj # core object
# get MR for equivalence ratio = 1
MRstart = C.ceaObj.getMRforER( ERr=1.0 )
MRlo = MRstart / 3.0
MRhi = MRstart * 3.0
def get_ispdel( MR ):
C.reset_attr('MRcore', MR, re_evaluate=True)
self.R.calc_all_eff()
return C.IspDel
MRopt, IspMax = search_max(get_ispdel, MRlo, MRhi, tol=0.01)
print('MRopt=%g, IspMax=%g sec'%(MRopt, IspMax) )
# use MRopt to reset everything
get_ispdel( MRopt )
return MRopt
def test_overall_Isp_efficiency(self):
"""test overall Isp efficiency"""
R = RocketThruster(name='overall_Isp_efficiency')
R.set_eff_model(eff_name='Div', model_name='simple fit')
R.scale_Rt_to_Thrust(ThrustLbf=400.0, Pamb=0.0, use_scipy=False)
#R.summ_print()
self.assertAlmostEqual(R.coreObj.effObj('Isp'), 0.96889, places=3)
self.assertAlmostEqual(R.coreObj.effObj('BL'), 0.992297, places=3)
self.assertAlmostEqual(R('pulse_quality'), 0.8, places=3)
R.scale_Rt_to_Thrust(ThrustLbf=500.0, Pamb=0.0, use_scipy=False)
self.assertAlmostEqual(R.coreObj.Fambient, 500, places=3)
R.scale_Rt_to_Thrust(ThrustLbf=500.0, Pamb=0.0, use_scipy=True)
self.assertAlmostEqual(R.coreObj.Fambient, 500, places=3)
R.set_eff_model(eff_name='BL', model_name='NASA-SP8120')
R.noz_regen_eps = 6
R.scale_Rt_to_Thrust(ThrustLbf=400.0, Pamb=0.0, use_scipy=False)
#R.summ_print()
self.assertAlmostEqual(R.coreObj.effObj('Isp'), 0.969825, places=3)
self.assertAlmostEqual(R.coreObj.effObj('BL'), 0.993258, places=3)
import webbrowser
import os
from rocketisp.geometry import Geometry
from rocketisp.efficiencies import Efficiencies
from rocketisp.stream_tubes import CoreStream
from rocketisp.rocket_isp import RocketThruster
# create CoreStream with area ratio=375:1, Pc=137, FFC=30% and effERE=0.99
C = CoreStream(geomObj=Geometry(eps=375),
effObj=Efficiencies(ERE=0.99),
pcentFFC=30,
oxName='N2O4',
fuelName='N2H4',
MRcore=1.26,
Pc=137,
Pamb=0)
# instantiate RocketThruster
R = RocketThruster(name='100 lbf Aerojet HiPAT R-4D', coreObj=C)
R.scale_Rt_to_Thrust(100, Pamb=0.0)
#R.summ_print()
fsave = 'hipat_at_opt_mr.html'
fOut = open(fsave, 'w')
fOut.write(R.get_html_file_str())
fOut.close()
webbrowser.open(os.path.abspath(fsave))
geomObj = Geometry(Rthrt=1,
CR=2.5, eps=62.5, pcentBell=72.3,
RupThroat=1.5, RdwnThroat=1.0, RchmConv=1.0, cham_conv_deg=30,
LchmOvrDt=3.10, LchmMin=2.0, LchamberInp=None)
effObj = Efficiencies()
effObj.set_const('ERE', 0.98) # don't know injector details so set effERE=0.98
# It's an ablative chamber, so some FFC (fuel film cooling) is required... guess about 15%
core = CoreStream( geomObj=geomObj, effObj=effObj, pcentFFC=15.0,
oxName='N2O4', fuelName='A50', MRcore=1.6, Pc=100 )
R = RocketThruster(name='Apollo SPS',coreObj=core)
# scale geometry to give 20,500 lbf of thrust for current conditions
R.scale_Rt_to_Thrust( 20500 , Pamb=0.0 )
# figure out best mixture ratio to run the engine.
R.set_mr_to_max_ispdel()
# re-scale geometry to give 20,500 lbf of thrust after MR change
R.scale_Rt_to_Thrust( 20500 , Pamb=0.0 )
fsave = 'Apollo_SPS.html'
fOut = open(fsave , 'w')
fOut.write( R.get_html_file_str() )
fOut.close()
webbrowser.open( os.path.abspath(fsave) )
def calc_ODE_ODK_FROZ_isp(oxName='N2O4',
fuelName='MMH',
Pc=1000.0,
eps=10.0,
pcentBell=80.0,
Fvac=1000.0,
NumRuns=20,
do_show=True):
# ============ use RocketCEA to find MR range ===================
mc = MR_Temperature_Limits(oxName=oxName,
fuelName=fuelName,
PcNominal=Pc,
epsNominal=eps)
mr_peak = MR_Peak_At_EpsPc(
mc,
pc=Pc,
eps=eps,
ispType='CEAODE', # ispType can be CEAODE, CEAFROZEN
NterpSize=100)
print('Peak IspODE=%g sec at MR =' % mr_peak.ispPeak, mr_peak.mrPeak)
print()
print('MR at 97% Isp (on low side) =',
mr_peak.calc_mrLow_minus_NPcentIsp())
print('MR at 97% Isp (on high side) =',
mr_peak.calc_mrHigh_minus_NPcentIsp())
mr_lo = round(
mr_peak.mrLeftOfPeak -
(mr_peak.mrRightOfPeak - mr_peak.mrLeftOfPeak) / 10.0, 2)
mr_hi = round(mr_peak.mrRightOfPeak, 2)
delMR = (mr_hi - mr_lo) / (NumRuns - 1)
# ===============================
geomObj = Geometry(Rthrt=5.868 / 2,
CR=2.5,
eps=eps,
pcentBell=pcentBell,
RupThroat=1.5,
RdwnThroat=1.0,
RchmConv=1.0,
cham_conv_deg=30,
LchmOvrDt=3.10,
LchmMin=2.0,
LchamberInp=16)
core = CoreStream(geomObj,
oxName=oxName,
fuelName=fuelName,
MRcore=1.6,
Pc=Pc)
R = RocketThruster(name='sample', coreObj=core, injObj=None)
ispodeL = []
ispodkL = []
ispodfL = []
mrL = []
MR = mr_lo
for _ in range(NumRuns):
mrL.append(MR)
core.reset_attr('MRcore', MR, re_evaluate=True)
R.scale_Rt_to_Thrust(Fvac, Pamb=0.0, use_scipy=False)
ispodeL.append(R.coreObj.IspODE)
ispodkL.append(R.coreObj.IspODK)
ispodfL.append(R.coreObj.IspODF)
MR += delMR
# ======= find peaks ======
mr_ode_terp = InterpProp(mrL, ispodeL)
mr_ode_Peak, isp_ode_peak = gold_search_max(mr_ode_terp,
mrL[0],
mrL[-1],
tol=1.0e-5)
mr_odk_terp = InterpProp(mrL, ispodkL)
mr_odk_Peak, isp_odk_peak = gold_search_max(mr_odk_terp,
mrL[0],
mrL[-1],
tol=1.0e-5)
mr_odf_terp = InterpProp(mrL, ispodfL)
mr_odf_Peak, isp_odf_peak = gold_search_max(mr_odf_terp,
mrL[0],
mrL[-1],
tol=1.0e-5)
fig, ax = plt.subplots(figsize=(8, 6))
plt.plot(mrL, ispodeL, label='IspODE', color=COLORL[0])
plt.plot(mrL, ispodkL, label='IspODK', color=COLORL[1])
plt.plot(mrL, ispodfL, label='IspODF', color=COLORL[2])
# show ========= optimum MR difference ========
def span_mrpeak(isL):
minpt = min(isL)
maxpt = max(isL)
span = maxpt - minpt
return [maxpt - 0.8 * span, maxpt]
plt.plot([mr_ode_Peak, mr_ode_Peak],
span_mrpeak(ispodeL),
'--',
label='MRode=%.2f' % mr_ode_Peak,
linewidth=2,
color=COLORL[0])
plt.plot([mr_odk_Peak, mr_odk_Peak],
span_mrpeak(ispodkL),
'--',
label='MRodk=%.2f' % mr_odk_Peak,
linewidth=2,
color=COLORL[1])
plt.plot([mr_odf_Peak, mr_odf_Peak],
span_mrpeak(ispodfL),
'--',
label='MRodf=%.2f' % mr_odf_Peak,
linewidth=2,
color=COLORL[2])
isp_odk_peak = abs(isp_odk_peak)
plt.text(mr_odk_Peak,
isp_odk_peak,
'%i' % int(isp_odk_peak),
ha='left',
va='bottom',
transform=ax.transData,
color=COLORL[1])
plt.legend()
plt.ylabel('Isp (sec)')
plt.xlabel('Mixture Ratio')
plt.title( "%s/%s RocketIsp ODE ODK ODF\nFvac=%.0f lbf, Pc=%.0f psia, AR=%.0f:1, %%Bell=%.0f%%"%\
(oxName, fuelName, Fvac, Pc, eps, pcentBell))
png_name = 'odekf_%s_%s_Fvac%g_Pc%g_eps%g.png' % (oxName, fuelName, Fvac,
Pc, eps)
plt.savefig(png_name, dpi=120)
if do_show:
plt.show()
from rocketisp.examples.compare_vals import compare_header, compare
geomObj = Geometry(Rthrt=Rthrt,
CR=(5.131/2.4724)**2, eps=eps, pcentBell=70,
RupThroat=1.5, RdwnThroat=1.0, RchmConv=1.0, cham_conv_deg=30,
LchmOvrDt=2.4842/2, LchmMin=2.0, LchamberInp=15.0)
effObj = Efficiencies()
effObj.set_const('ERE', 0.9892 )
core = CoreStream( geomObj, effObj, oxName='LOX', fuelName='LH2', MRcore=MRcore,
Pc=Pc, CdThroat=CdThroat)
R = RocketThruster(name='RL10',coreObj=core, injObj=None, calc_CdThroat=False,
noz_regen_eps=eps)
R.scale_Rt_to_Thrust( Fvac, Pamb=0.0 , use_scipy=False )
compare_header()
compare('Fvacuum',Fvac, core('FvacTotal'))
compare('Isp Vacuum', Isp, core('IspDel'))
compare('Cstar ODE', cstarODE, core('cstarODE'))
print()
compare('Fuel Flow Rate', wdotFuel, core('wdotFlCore'))
compare('Ox Flow Rate', wdotOx, core('wdotOxCore'))
R.summ_print()
#geomObj.plot_geometry()
print('mr_hi =', mr_hi)
# =========== create RocketIsp structures
# create CoreStream with area ratio=375:1, Pc=137, FFC=30% and effERE=0.99
C = CoreStream(geomObj=Geometry(eps=eps),
effObj=Efficiencies(ERE=1.0, Div=1.0, BL=1.0, TP=1.0),
pcentFFC=0,
oxName=oxName,
fuelName=fuelName,
MRcore=mr_lo,
Pc=Pc,
Pamb=0)
# instantiate RocketThruster
R = RocketThruster(name='Sample Thruster', coreObj=C)
R.scale_Rt_to_Thrust(ThrustLbf=Fvac, Pamb=0.0)
#R.summ_print()
# =========================================================
# generate data
ispodeL = [] # list of IspODE (one-dimensional equilibrium)
ispodkL = [] # list of IspODK (one-dimensional kinetic)
ispodfL = [] # list of IspODF (frozen)
mrcoreL = [] # list of MRcore (core stream tube mixture ratio)
for MRcore in np.linspace(mr_lo, mr_hi, num=60):
C.reset_attr('MRcore', MRcore)
R.scale_Rt_to_Thrust(Fvac, Pamb=0.0)
ispodeL.append(C('IspODE'))
ispodkL.append(C('IspODK'))
ispodfL.append(C('IspODF'))
mrcoreL.append(C('MRcore'))