piston.py (Source)

"""
Two reactors separated by a piston

Gas 1: a stoichiometric H2/O2/Ar mixture
Gas 2: a wet CO/O2 mixture

    -------------------------------------
    |          ||                       |
    |          ||                       |
    |  gas 1   ||        gas 2          |
    |          ||                       |
    |          ||                       |
    -------------------------------------

The two volumes are connected by an adiabatic free piston. The piston speed is
proportional to the pressure difference between the two chambers.

Note that each side uses a *different* reaction mechanism
"""

import sys

import cantera as ct

fmt = '%10.3f  %10.1f  %10.4f  %10.4g  %10.4g  %10.4g  %10.4g'
print('%10s  %10s  %10s  %10s  %10s  %10s %10s' % ('time [s]','T1 [K]','T2 [K]',
                                              'V1 [m^3]', 'V2 [m^3]',
                                              'V1+V2 [m^3]','X(CO)'))

gas1 = ct.Solution('h2o2.cti')
gas1.TPX = 900.0, ct.one_atm, 'H2:2, O2:1, AR:20'

gas2 = ct.Solution('gri30.xml')
gas2.TPX = 900.0, ct.one_atm, 'CO:2, H2O:0.01, O2:5'

r1 = ct.IdealGasReactor(gas1)
r1.volume = 0.5
r2 = ct.IdealGasReactor(gas2)
r2.volume = 0.1

# The wall is held fixed until t = 0.1 s, then released to allow the pressure to
# equilibrate.
def v(t):
    if t < 0.1:
        return 0.0
    else:
        return (r1.thermo.P - r2.thermo.P) * 1e-4

w = ct.Wall(r1, r2, velocity=v)

net = ct.ReactorNet([r1, r2])

states1 = ct.SolutionArray(r1.thermo, extra=['t','v'])
states2 = ct.SolutionArray(r2.thermo, extra=['t','v'])

for n in range(200):
    time = (n+1)*0.001
    net.advance(time)
    if n % 4 == 3:
        print(fmt % (time, r1.T, r2.T, r1.volume, r2.volume,
                     r1.volume + r2.volume, r2.thermo['CO'].X[0]))

    states1.append(r1.thermo.state, t=1000*time, v=r1.volume)
    states2.append(r2.thermo.state, t=1000*time, v=r2.volume)

# plot the results if matplotlib is installed.
if '--plot' in sys.argv:
    import matplotlib.pyplot as plt
    plt.subplot(2,2,1)
    plt.plot(states1.t, states1.T, '-', states2.t, states2.T, 'r-')
    plt.xlabel('Time (ms)')
    plt.ylabel('Temperature (K)')
    plt.subplot(2,2,2)
    plt.plot(states1.t, states1.v,'-', states2.t, states2.v, 'r-',
             states1.t, states1.v + states2.v, 'g-')
    plt.xlabel('Time (ms)')
    plt.ylabel('Volume (m3)')
    plt.subplot(2,2,3)
    plt.plot(states2.t, states2('CO').X)
    plt.xlabel('Time (ms)')
    plt.ylabel('CO Mole Fraction (right)')
    plt.subplot(2,2,4)
    plt.plot(states1.t, states1('H2').X)
    plt.xlabel('Time (ms)')
    plt.ylabel('H2 Mole Fraction (left)')
    plt.tight_layout()
    plt.show()

else:
    print("""To view a plot of these results, run this script with the option --plot""")