2528df0f75
These changes make it unnecessary to copy header files around during the build process, which tends to confuse IDEs and debuggers. The headers which comprise Cantera's external C++ interface are now in the 'include' directory. All of the samples and demos are now in the 'samples' subdirectory.
63 lines
1.7 KiB
Python
63 lines
1.7 KiB
Python
from Cantera import *
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import math
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def equilSoundSpeeds(gas, rtol = 1.0e-6, maxiter = 5000):
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"""Returns a tuple containing the equilibrium and frozen sound
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speeds for a gas with an equilibrium composition. The gas is
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first set to an equilibrium state at the temperature and pressure
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of the gas, since otherwise the equilibrium sound speed is not
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defined.
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"""
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# set the gas to equilibrium at its current T and P
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gas.equilibrate('TP', rtol = rtol, maxiter = maxiter)
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# save properties
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s0 = gas.entropy_mass()
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p0 = gas.pressure()
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r0 = gas.density()
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# perturb the pressure
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p1 = p0*1.0001
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# set the gas to a state with the same entropy and composition but
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# the perturbed pressure
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gas.set(S = s0, P = p1)
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# save the density for this case for the frozen sound speed
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rho_frozen = gas.density()
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# now equilibrate the gas holding S and P constant
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gas.equilibrate("SP", loglevel=0, rtol = rtol, maxiter = maxiter) # , rtol = 1.0e-3, maxsteps=10000)
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r1 = gas.density()
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# equilibrium sound speed
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aequil = math.sqrt((p1 - p0)/(r1 - r0));
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# frozen sound speed
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afrozen = math.sqrt((p1 - p0)/(rho_frozen - r0));
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# compute the frozen sound speed using the ideal gas
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# expression as a check
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cp = gas.cp_mass()
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cv = gas.cv_mass()
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gamma = cp/cv
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afrozen2 = math.sqrt(gamma*GasConstant*gas.temperature()
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/gas.meanMolecularWeight())
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return (aequil, afrozen, afrozen2)
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# test program
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if __name__ == "__main__":
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gas = GRI30()
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gas.set(X = 'CH4:1.00, O2:2.0, N2:7.52')
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for n in range(27):
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temp = 300.0 + n*100.0
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gas.set(T = temp, P = OneAtm)
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print temp, equilSoundSpeeds(gas)
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