# Coverage for rocketcea\separated_Cf.py : 99%

## 71 statements 70 run 1 missing 0 excluded

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 | import rocketcea.Isp as Isp #print( 'imported',Isp.__file__ ) def ambientCf(gam=1.25, epsTot=20.0, Pc=200.0, Pamb=14.7): PcOvPe = Isp.CalcPCoPE(gam, epsTot) if Pamb > 0.0: CfOvCfvacAtEsep, CfOvCfvac, Cfsep, CfiVac, CfiAmbSimple, CfVac, epsSep, Psep = \ sepNozzleCf(gam, epsTot, Pc, Pamb) else: CfVac = Isp.CalcCFvac(gam, PcOvPe) Psep = 0.0 Pexit = Pc / PcOvPe if Pexit > Psep: #print( 'Not Separated, Cfsep =',Cfsep) #print( 'CfVac - Pamb*epsTot/Pc = ',CfVac - Pamb*epsTot/Pc) Cf = CfVac - Pamb*epsTot/Pc if Pexit > Pamb: mode = 'UnderExpanded Pe=%g'%Pexit else: mode = 'OverExpanded Pe=%g'%Pexit else: #print( 'separated, Cfsep =',Cfsep) #print( 'Simplified Cfsep =',CfiAmbSimple) Cf = Cfsep mode = 'Separated Psep=%g, epsSep=%.1f'%(Psep, epsSep) CfOverCfvac = Cf / CfVac return Cf, CfOverCfvac, mode def sepNozzleCf(gam=1.25, epsTot=20.0, Pc=200.0, Pamb=14.7): '''Uses approach of Sherwin Kalt and David Badal in: "Conical Rocket Nozzle Performance under Flow Separated Conditions" This routine calculates an efficiency factor to apply to the Ispvac or Cfvac of the nozzle IspAmb = CfOvCfvac * IspVac or to the vacuum performance of the nozzle at the separation point IspAmb = CfOvCfvacAtEsep * IspVac(at epsSep) ''' PcOvPe = Isp.CalcPCoPE(gam,epsTot) CfVac = Isp.CalcCFvac(gam, PcOvPe) # this is Kalt&Badal correlation for Pi (incipient separation pressure) PiOvPa = (2./3.)*(Pc/Pamb)**(-0.2) Pi = PiOvPa * Pamb Psep = Pi # area ratio and Cfvac that correspond to the point of Pi epsSep = Isp.CalcEps(gam,Pc/Pi) epsSep = epsSep PcOvPesep = Isp.CalcPCoPE(gam,epsSep) CfiVac = Isp.CalcCFvac(gam, PcOvPesep) CfiAmbSimple = CfiVac - Pamb*epsSep/Pc # eps95 is the area ratio at which the internal pressure = 0.95 * Pamb # c = result of simultaneous solution of eps95 = epsSep + (epsSep-1)/2.4 = epsSep + (epsTot-epsSep)/1.45 c = 2.4/1.45 if epsSep <= epsTot*c/(1.+c) + 1./(1.+c): eps95 = epsSep + (epsSep-1)/2.4 else: eps95 = epsSep + (epsTot-epsSep) P95 = 0.95 * Pamb cf_integral_iTo95 = 0.55 *(Pi+P95)*(eps95-epsSep)/Pc cf_integral_95ToExit = (0.975*eps95 + 0.025*epsTot)*Pamb/Pc Cf = CfiVac + cf_integral_iTo95 - cf_integral_95ToExit CfOvCfvac = Cf / CfVac CfOvCfvacAtEsep = Cf / CfiVac return CfOvCfvacAtEsep, CfOvCfvac, Cf, CfiVac, CfiAmbSimple, CfVac, epsSep, Psep if __name__ == "__main__": import csv csvfilename = 'separated_Noz.csv' print( "saving data to CSV file",csvfilename) csvWriter = csv.writer(open(csvfilename, "w"), dialect='excel') csvWriter.writerow( ['gam','EpsTot','Pc','Pamb','IspVac_AtEpsTot','IspAmb_Separated','IspAmb_Simple', 'Cf/Cfvac_AtEpsTot','Cf/Cfvac_AtEpsSep','Cf','CfiVac','CfiAmbSimple','CfVac','EpsSep'] ) gam,epsTot,Pc,Pamb = 1.25, 25.0, 200., 14.7 IspVac = 316.0 CfOvCfvacAtEsep, CfOvCfvac, Cfsep, CfiVac, CfiAmbSimple,CfVac, epsSep, Psep = sepNozzleCf(gam=gam, epsTot=epsTot, Pc=Pc, Pamb=Pamb) IspAmb = IspVac * CfOvCfvac IspSimpleAtEsep = IspVac * CfiAmbSimple/CfVac csvWriter.writerow( [gam,epsTot,Pc,Pamb, IspVac, IspAmb, IspSimpleAtEsep, CfOvCfvac,CfOvCfvacAtEsep,Cfsep,CfiVac,CfiAmbSimple,CfVac,epsSep] ) print( 'gam=%g, epsTot=%g, Pc=%g, Pamb=%g'%(gam,epsTot,Pc,Pamb)) print( 'CfOvCfvacAtEsep, CfOvCfvac',CfOvCfvacAtEsep, CfOvCfvac) print( 'Cfsep, CfiAmbSimple', Cfsep, CfiAmbSimple) print( 'CfiVac CfVac', CfiVac, CfVac) print( 'epsSep', epsSep) print( ) Pc=250.0 epsTot=20.45 IspVac=321.3 CfOvCfvacAtEsep, CfOvCfvac, Cfsep, CfiVac, CfiAmbSimple,CfVac, epsSep, Psep = sepNozzleCf(gam=gam, epsTot=epsTot, Pc=Pc, Pamb=Pamb) IspAmb = IspVac * CfOvCfvac IspSimpleAtEsep = IspVac * CfiAmbSimple/CfVac csvWriter.writerow( [gam,epsTot,Pc,Pamb, IspVac, IspAmb, IspSimpleAtEsep, CfOvCfvac,CfOvCfvacAtEsep,Cfsep,CfiVac,CfiAmbSimple,CfVac,epsSep] ) print( 'gam=%g, epsTot=%g, Pc=%g, Pamb=%g'%(gam,epsTot,Pc,Pamb)) print( 'CfOvCfvacAtEsep, CfOvCfvac',CfOvCfvacAtEsep, CfOvCfvac) print( 'Cfsep, CfiAmbSimple', Cfsep, CfiAmbSimple) print( 'CfiVac CfVac', CfiVac, CfVac) print( 'epsSep', epsSep) print( ) ambientCf(gam=1.25, epsTot=20.0, Pc=200.0, Pamb=14.7)