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how to get Sutherland and JANAF coefficients of air? |
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September 18, 2018, 15:55 |
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#61 |
Member
Join Date: Sep 2018
Location: France
Posts: 62
Rep Power: 8 |
Hello guys,
I used the code made by arvindpj (post #57) by running it on python 3.6 and cantera 2.4 but it does'nt work. I have attached the error message; does anyone have a clue? Cheers. |
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September 18, 2018, 16:15 |
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#62 |
Senior Member
Oskar
Join Date: Nov 2015
Location: Poland
Posts: 184
Rep Power: 11 |
Here is my new "Old NASA Thermo Generator"
Give it a try. Code:
########################### #Old NASA Thermo Generator# # Oskar Zuranski # # Warsaw, Poland,2018 # ########################### import sys import cantera as ct import numpy as np import math from numpy.linalg import inv ####################################################################### # USER EDITABLE PART ####################################################################### gas = ct.Solution('gri30.cti','gri30_mix') #gas = ct.Solution('Dagaut_Ori.cti') #gas = ct.Solution('curran.cti') q = 'C2H2:1' p = 101325 Tlow = 300.0 Tcommon = 1000.0 Thigh = 5000.0 step = 100 ####################################################################### # END OF USER EDITABLE PART ####################################################################### ####################################################################### # LOW TEMPERATURE RANGE ####################################################################### # reference temperature for standard enthalpy/entropy Tref = 298.15 #create gas gas.TPX = Tlow, p, q # create empty temperature table for low temperature range templist = [0 for x in range(step+1)] np.float64(templist) #set temperatures in temperature table for low temperature range for i in range (step+1): templist[i] = Tlow+i*((Tcommon-Tlow)/step) #create X matrix tab = [[0 for x in range(5)] for y in range(5)] np.float64(tab) #set X matrix coefficients for a in range(5): for b in range(5): for i in range (step+1): tab[a][b] += templist[i]**(b+a) #create Y matrix tab2 = [0 for x in range(5)] np.float64(tab2) #set Y matrix coefficients for a in range(5): for i in range(step+1): gas.TPX = templist[i], gas.P, gas.X tab2[a] += gas.cp_mole/ct.gas_constant*templist[i]**a # invert X matrix inverse = inv(tab) # multiply X^-1*Y low_temp_range = np.matmul(inverse,tab2) print 'Low temperature range coefficients:' print 'a1 = ',low_temp_range[0] print 'a2 = ',low_temp_range[1] print 'a3 = ',low_temp_range[2] print 'a4 = ',low_temp_range[3] print 'a5 = ',low_temp_range[4] gas.TPX = Tref, gas.P, gas.X hOffset = gas.enthalpy_mole/ct.gas_constant - (low_temp_range[0]*Tref+low_temp_range[1]/2.0*Tref**2+low_temp_range[2]/3.0*Tref**3+low_temp_range[3]/4.0*Tref**4+low_temp_range[4]/5.0*Tref**5) sOffset = gas.entropy_mole/ct.gas_constant - (low_temp_range[0]*np.log(Tref)+low_temp_range[1]*Tref+low_temp_range[2]/2.0*Tref**2+low_temp_range[3]/3.0*Tref**3+low_temp_range[4]/4.0*Tref**4) print 'a6 = ', hOffset print 'a7 = ', sOffset print '' ####################################################################### # HIGH TEMPERATURE RANGE ####################################################################### gas.TPX = Tcommon, gas.P, gas.X hbak = gas.enthalpy_mole/ct.gas_constant sbak = gas.entropy_mole/ct.gas_constant # clear tabs templist = [0 for x in range(step+1)] tab = [[0 for x in range(5)] for y in range(5)] tab2 = [0 for x in range(5)] #set temperatures in temperature table for high temperature range for i in range (step+1): templist[i] = Tcommon+i*((Thigh-Tcommon)/step) #set X matrix coefficients for a in range(5): for b in range(5): for i in range (step+1): tab[a][b] += templist[i]**(b+a) #set Y matrix coefficients for a in range(5): for i in range(step+1): gas.TPX = templist[i], gas.P, gas.X tab2[a] += gas.cp_mole/ct.gas_constant*templist[i]**a # inverse X matrix inverse = inv(tab) # multiply X^-1*Y high_temp_range = np.matmul(inverse,tab2) print 'High temperature range coefficients:' print 'a1 = ', high_temp_range[0] print 'a2 = ', high_temp_range[1] print 'a3 = ', high_temp_range[2] print 'a4 = ', high_temp_range[3] print 'a5 = ', high_temp_range[4] hOffset = hbak - (high_temp_range[0]*Tcommon+high_temp_range[1]/2.0*Tcommon**2+high_temp_range[2]/3.0*Tcommon**3+high_temp_range[3]/4.0*Tcommon**4+high_temp_range[4]/5.0*Tcommon**5) sOffset = sbak - (high_temp_range[0]*np.log(Tcommon)+high_temp_range[1]*Tcommon+high_temp_range[2]/2.0*Tcommon**2+high_temp_range[3]/3.0*Tcommon**3+high_temp_range[4]/4.0*Tcommon**4) print 'a6 = ', hOffset print 'a7 = ', sOffset print '' print 'M = ', gas.mean_molecular_weight, '[g/mol]' |
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September 18, 2018, 16:25 |
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#63 |
Member
Arvind Jay
Join Date: Sep 2012
Posts: 97
Rep Power: 15 |
Try this:
Code:
from cantera import * import numpy as np import sys gas = Solution('gri30.cti') #q = 'CH4:1' #q = 'O2:7, H2O:95, N2:719, CO:14, CO2:158, NO:4' #Mole fraction #gas.TPX = 273.16,101325,q Pin = 101325 #Pa Tin = 1200 #K qmass = 'N2:.76, CO2:.13, H2O:.11' gas.TPY = Tin,Pin,qmass gasmass = gas.Y gasmole = gas.X gasnames = gas.species_names n=0 print gas() print "Temperature:\t", gas.T, "K" print "Pressure:\t", gas.P, "Pa" print "" print "Molar fractions:" for i in range(gas.n_species): if gasmole[i]!=0: n+=1 if gasmole[i]>=0.1: print n, gasnames[i], "\t{0:.10f}".format(100.0*gasmole[i]), "%" else: print n, gasnames[i], "\t {0:.10f}".format(100.0*gasmole[i]), "%" n=0 print "" print "Mass fractions:" for i in range(gas.n_species): if gasmass[i]!=0: n+=1 if gasmass[i]>=0.1: print n, gasnames[i], "\t{0:.10f}".format(100.0*gasmass[i]), "%" else: print n, gasnames[i], "\t {0:.10f}".format(100.0*gasmass[i]), "%" #kg/m^3\t{0:.15f}".format(gasmole[i]), "mol/m^3" print "" print "Mean molar mass:" print "M =", gas.mean_molecular_weight, "kg/kmol" print "" print "Density:" print "rho =", gas.density, "kg/m^3" print "rho =", gas.density_mole, "kmol/m^3" print "" print "Specific gas constant:" print "R =",gas_constant/gas.mean_molecular_weight, "J/kg/K" #CHheck units ?????????? print "" print "Molar heat capacities:" print "Cp =", gas.cp_mole/1000.0, "J/mol/K" print "Cv =", gas.cv_mole/1000.0, "J/mol/K" print "" print "Mass heat capacities:" print "Cp =", gas.cp_mass, "J/kg/K" print "Cv =", gas.cv_mass, "J/kg/K" print "" print "Heat capacity ratio" print "kappa =", gas.cp_mole/gas.cv_mole |
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September 19, 2018, 07:27 |
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#64 |
Member
Join Date: Sep 2018
Location: France
Posts: 62
Rep Power: 8 |
Thanks a lot guys,
It works for both scripts you gave me. For the script to calculate the Janaf coefficients, the results seem to be quite close from those coefficients in OpenFOAM 5 by choosing the nitrogen (except for a2, a3 and a4 for the lower interval where the gap is high). Cheers. Last edited by john myce; September 19, 2018 at 12:30. |
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October 18, 2022, 11:17 |
How the low_enthalpy_offset and high_enthalpy_offset are calculated
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#65 |
Senior Member
Mieszko Młody
Join Date: Mar 2009
Location: POLAND, USA
Posts: 145
Rep Power: 17 |
Hi,
I am trying to understand how the low_enthalpy_offset and high_enthalpy_offset are calculated ? what is gas.enthalpy_mass() ? Thank you. Mieszko |
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janaf, openfoam, sutherland |
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