def test_use_Mpa_as_input_Pc(self): """test use Mpa as input Pc""" C = CEA_Obj( oxName='LOX', fuelName='LH2', fac_CR=None) CwU = CEA_Obj_w_units( oxName='LOX', fuelName='LH2', pressure_units='MPa', fac_CR=None) a = C.get_Isp(Pc=1000.0, MR=6.0, eps=40.0) b = CwU.get_Isp(Pc=1000.0/145.037738, MR=6.0, eps=40.0) self.assertAlmostEqual(a, b, delta=0.01)
def OFtrade(fu, ox, P, N, OFratio, pltname): # O/F ratio trade (OFratio needs to be a vector array) # fu: name of fuel (string, as defined in rocketcea documentation or newly added fuels) # ox: name of ox (string, as defined in rocketcea documentation of newly added fuels) # P: chamber pressure (either a single number, list of numbers, or range()) # N: number of desired O/F ratios to sweep over # OFratio: values of O/F ratios (length of this list must match value of N) # supAR: fixed nozzle expansion ratio C = CEA_Obj( oxName=ox, fuelName=fu, isp_units='sec', cstar_units='m/s') # define CEA object to operate on for rocketCEA if isinstance(P, int) == True: # if P is only one value y = 1 else: y = len(P) # preallocate vars ISP = np.zeros([y, OFratio.shape[0]]) # isp Cstar = np.zeros([y, OFratio.shape[0]]) # cstar eff PCPE = np.zeros([y, OFratio.shape[0]]) # pc/pe cpcv = np.zeros([y, OFratio.shape[0] ]) # ratio of specific heats in thrust chamber fe_pcpe = np.zeros([y, OFratio.shape[0] ]) # nozzle area ratio for fully expanded flow for x in range(y): if y == 1: Pc = P # integers can't be called :( legends = str(Pc) else: Pc = P[x] # chamber pressure legends = P pr = Pc / 14.7 # pc/pe for fully expanded flo for i in range(N): fe_pcpe[x, :] = C.get_eps_at_PcOvPe(Pc=Pc, MR=OFratio[i], PcOvPe=pr) ISP[x, i] = C.get_Isp(Pc=Pc, MR=OFratio[i], eps=fe_pcpe[x, i]) # ISP vacuum Cstar[x, i] = C.get_Cstar(Pc=Pc, MR=OFratio[i]) # Cstar efficiency fe_pcpe[x, i] = C.get_PcOvPe(Pc=Pc, MR=OFratio[i], eps=fe_pcpe[x, i]) # Pc/Pe cpcv[x, i] = C.get_Chamber_Cp(Pc=Pc, MR=OFratio[i], eps=fe_pcpe[x, i]) # cp/cv # generate plots for ISP, Cstar, and Pchamb/Pexit # plots(OFratio,ISP,"O/F ratio","ISP (s)", pltname+"isp.png" , legends ) # isp plot # plots(OFratio,Cstar,"O/F ratio","Cstar", pltname+"cstar.png" , legends ) # Cstar plot # plots(OFratio,PCPE,"O/F ratio","Pc/Pe", pltname+"pcpe.png" , legends ) # Pc/Pe plot return ISP, Cstar, fe_pcpe, cpcv
def rocket_vars(fu, ox, pcham): C = CEA_Obj( oxName=ox, fuelName=fu, isp_units='sec', cstar_units='m/s') # define CEA object to operate on for rocketCEA OFratio = np.linspace(0.1, 5., 50, endpoint=True) # OF ratio by mass ISP = np.zeros(OFratio.shape) # isp Cstar = np.zeros(OFratio.shape) # cstar efficiency PCPE = np.zeros(OFratio.shape) # p_chamber / p_exit supAR = 1 # supersonic area ratio (1 = converging nozzle only) for i in range(50): ISP[i] = C.get_Isp(pcham, MR=OFratio[i], eps=supAR) # ISP vacuum Cstar[i] = C.get_Cstar(pcham, MR=OFratio[i]) # Cstar efficiency PCPE[i] = C.get_Throat_PcOvPe( pcham, MR=OFratio[i] ) # throat Pc/Pe (we will be using a converging nozzle) return ISP, Cstar, PCPE
def ARtrade(fu, ox, P, N, OFratio, supAR, pltname): # expansion ratio trade # fu: name of fuel (string, as defined in rocketcea documentation or newly added fuels) # ox: name of ox (string, as defined in rocketcea documentation of newly added fuels) # P: chamber pressure (either a single number, list of numbers, or range()) # N: number of desired supersonic area ratios (nozzle expansion ratio) to sweep over # OFratio: fixed O/F ratio for this trade # supAR: values of supersonic area ratios (length of this list must match value of N) C = CEA_Obj( oxName=ox, fuelName=fu, isp_units='sec', cstar_units='m/s') # define CEA object to operate on for rocketCEA if isinstance(P, int) == True: # if P is only one value y = 1 else: y = len(P) # preallocate vars ISP = np.zeros([y, supAR.shape[0]]) # isp Cstar = np.zeros([y, supAR.shape[0]]) # cstar eff PCPE = np.zeros([y, supAR.shape[0]]) # pc/pe cpcv = np.zeros([y, supAR.shape[0] ]) # ratio of specific heats in thrust chamber for x in range(y): if y == 1: Pc = P # integers can't be called :( legends = str(Pc) else: Pc = P[x] # chamber pressure legends = P for i in range(N): ISP[x, i] = C.get_Isp(Pc=Pc, MR=OFratio, eps=supAR[i]) # ISP vacuum Cstar[x, i] = C.get_Cstar(Pc=Pc, MR=OFratio) # Cstar efficiency PCPE[x, i] = C.get_PcOvPe(Pc=Pc, MR=OFratio, eps=supAR[i]) # Pc/Pe cpcv[x, i] = C.get_Chamber_Cp(Pc=Pc, MR=OFratio, eps=supAR[i]) # cp/cv # generate plots for ISP, Cstar, and Pchamb/Pexit. Replace the last input with the vectory array of pressures # plots(supAR,ISP,"Ae/At","ISP (s)", pltname+"isp.png" , legends ) # isp plot # plots(supAR,Cstar,"Ae/At","Cstar", pltname+"cstar.png" , legends ) # Cstar plot # plots(supAR,PCPE,"Ae/At","Pc/Pe", pltname+"pcpe.png" , legends ) # Pc/Pe plot return ISP, Cstar, PCPE, cpcv