def eos_derivatives(gas0, gmodel, tol=0.0001):
# Finite difference evaluation, assuming that gas0 is valid state already.
gas1 = GasState(gmodel)
gas1.copy_values(gas0)
p0 = gas0.p; rho0 = gas0.rho; u0 = gas0.u
#
drho = rho0 * tol; gas1.rho = rho0 + drho
gas1.update_thermo_from_rhou()
dpdrho = (gas1.p - p0)/drho
#
gas1.rho = rho0; du = u0 * tol; gas1.u = u0 + du
gas1.update_thermo_from_rhou()
dpdu = (gas1.p - p0)/du
#
return dpdrho, dpdu
# ideal-shock-test.py
#
# $ prep-gas ideal-air.inp ideal-air-gas-model.lua
# $ python3 ideal-shock-test.py
#
# PJ, 2019-11-28
#
import math
from eilmer.gas import GasModel, GasState, GasFlow
gmodel = GasModel('ideal-air-gas-model.lua')
state1 = GasState(gmodel)
state1.p = 125.0e3 # Pa
state1.T = 300.0 # K
state1.update_thermo_from_pT()
state1.update_sound_speed()
print("state1: %s" % state1)
print("normal shock (in ideal gas), given shock speed")
vs = 2414.0
state2 = GasState(gmodel)
flow = GasFlow(gmodel)
v2, vg = flow.ideal_shock(state1, vs, state2)
print("v2=%g vg=%g" % (v2, vg))
print("state2: %s" % state2)
# A script to compute the viscosity and thermal conductivity
# of air (as a mixture of N2 and O2) from 200 -- 20000 K.
#
# Author: Peter J. and Rowan J. Gollan
# Date: 2019-11-21
#
# To run this script:
# $ prep-gas thermally-perfect-N2-O2.inp thermally-perfect-N2-O2.lua
# $ python3 transport-properties-for-air.py
#
from eilmer.gas import GasModel, GasState
gasModelFile = 'thermally-perfect-N2-O2.lua'
gmodel = GasModel(gasModelFile)
gs = GasState(gmodel)
gs.p = 1.0e5 # Pa
gs.massf = {"N2":0.78, "O2":0.22} # approximation for the composition of air
outputFile = 'trans-props-air.dat'
print("Opening file for writing: %s" % outputFile)
f = open(outputFile, "w")
f.write("# 1:T[K] 2:mu[Pa.s] 3:k[W/(m.K)]\n")
lowT = 200.0
dT = 100.0
for i in range(199):
gs.T = dT*i + lowT
gs.update_thermo_from_pT()
gs.update_trans_coeffs()
# $ python3 conical-shock-test.py
#
# PJ, 2019-12-01
#
import math
def approxEqual(a, b):
result = math.isclose(a, b, rel_tol=1.0e-2, abs_tol=1.0e-5)
# print("a=",a, "b=",b, "rel=",(a-b)/b, "abs=",a-b, "result=",result)
return result
from eilmer.gas import GasModel, GasState, GasFlow
m1 = 1.5
print("Conical-shock demo for m1=%g" % m1)
gmodel = GasModel('cea-air13species-gas-model.lua')
state1 = GasState(gmodel)
state1.p = 100.0e3 # Pa
state1.T = 300.0 # K ideal air, not high T
state1.update_thermo_from_pT()
state1.update_sound_speed()
print("state1: %s" % state1)
v1 = m1*state1.a
print("v1=%g" % v1)
beta = 45.0 * math.pi/180.0
print(" given beta(degrees)=%g" % (beta*180/math.pi))
state_c = GasState(gmodel)
flow = GasFlow(gmodel)
theta_c, v_c = flow.theta_cone(state1, v1, beta, state_c)
print(" theta_c=%g degrees" % (theta_c*180/math.pi))
print(" v_c=%g" % (v_c))
# Typical use:
# $ python3 poshax.py
#
#------------------------------------------------------------------
from eilmer.gas import GasModel, GasState, GasFlow, ThermochemicalReactor
debug = False
print("Initialise a gas model.")
print("air 7 species Gupta-et-al reactions")
gmodel = GasModel("air-7sp-gas-model.lua")
nsp = gmodel.n_species
nmodes = gmodel.n_modes
if debug: print("nsp=", nsp, " nmodes=", nmodes, " gmodel=", gmodel)
reactor = ThermochemicalReactor(gmodel, "air-7sp-chemistry.lua")
# The example here matches the case discussed on page 63 of the thesis.
state1 = GasState(gmodel)
state1.p = 133.3 # Pa
state1.T = 300.0 # degree K
state1.massf = {"N2": 0.78, "O2": 0.22}
print("Free stream conditions, before the shock.")
state1.update_thermo_from_pT()
state1.update_sound_speed()
print(" state1: %s" % state1)
mach1 = 12.28
v1 = mach1 * state1.a
print("mach1:", mach1, "v1:", v1)
print("Stationary normal shock with chemically-frozen gas.")
flow = GasFlow(gmodel)
state2 = GasState(gmodel)
v2, vg = flow.normal_shock(state1, v1, state2)
#
# PJ, 2019-11-30
#
import math
def approxEqual(a, b):
result = math.isclose(a, b, rel_tol=1.0e-2, abs_tol=1.0e-5)
# print("a=",a, "b=",b, "rel=",(a-b)/b, "abs=",a-b, "result=",result)
return result
from eilmer.gas import GasModel, GasState, GasFlow
gmodel = GasModel('cea-air13species-gas-model.lua')
state1 = GasState(gmodel)
state1.p = 125.0e3 # Pa
state1.T = 300.0 # K
state1.update_thermo_from_pT()
state1.update_sound_speed()
print("Initial test gas:")
print(" state1: %s" % state1)
print("normal shock, given shock speed")
vs = 2414.0
print(" vs=%g" % vs)
state2 = GasState(gmodel)
flow = GasFlow(gmodel)
v2, vg = flow.normal_shock(state1, vs, state2)
print(" v2=%g vg=%g" % (v2, vg))
print(" state2: %s" % state2)
# gasModelFile = "ideal-air-gas-model.lua" # Alternative
gmodel = GasModel(gasModelFile)
if gmodel.n_species == 1:
print("Ideal air gas model.")
air_massf = {"air": 1.0}
else:
print("Thermally-perfect air model.")
air_massf = {"N2": 0.78, "O2": 0.22}
print("Compute cycle states:")
gs = [] # We will build up a list of gas states
h = [] # and enthalpies.
# Note that we want to use indices consistent with the Lua script,
# so we set up 5 elements but ignore the one with 0 index.
for i in range(5):
gs.append(GasState(gmodel))
h.append(0.0)
for i in range(1, 5):
gs[i].massf = air_massf
print(" Start with ambient air")
gs[1].p = 100.0e3
gs[1].T = 300.0
gs[1].update_thermo_from_pT()
s12 = gs[1].entropy
h[1] = gs[1].enthalpy
print(" Isentropic compression with a pressure ratio of 8")
gs[2].p = 8 * gs[1].p
gs[2].update_thermo_from_ps(s12)
h[2] = gs[2].enthalpy
# A simple fixed-volume reactor.
# PJ & RJG 2019-11-25
#
# To prepare:
# $ prep-gas nitrogen-2sp.inp nitrogen-2sp.lua
# $ prep-chem nitrogen-2sp.lua nitrogen-2sp-2r.lua chem.lua
#
# To run:
# $ python3 fvreactor.py
from eilmer.gas import GasModel, GasState, ThermochemicalReactor
gm = GasModel("nitrogen-2sp.lua")
reactor = ThermochemicalReactor(gm, "chem.lua")
gs = GasState(gm)
gs.p = 1.0e5 # Pa
gs.T = 4000.0 # degree K
gs.molef = {'N2': 2 / 3, 'N': 1 / 3}
gs.update_thermo_from_pT()
tFinal = 200.0e-6 # s
t = 0.0
dt = 1.0e-6
dtSuggest = 1.0e-11
print("# Start integration")
f = open("fvreactor.data", 'w')
f.write(
'# 1:t(s) 2:T(K) 3:p(Pa) 4:massf_N2 5:massf_N 6:conc_N2 7:conc_N\n')
f.write("%10.3e %10.3f %10.3e %20.12e %20.12e %20.12e %20.12e\n" %
(t, gs.T, gs.p, gs.massf[0], gs.massf[1], gs.conc[0], gs.conc[1]))