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.
90 lines
2.1 KiB
Python
Executable file
90 lines
2.1 KiB
Python
Executable file
from Cantera import *
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from Cantera.num import zeros
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import math
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def soundspeed(gas):
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"""The speed of sound. Assumes an ideal gas."""
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# if gas.isIdealGas():
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gamma = gas.cp_mass()/gas.cv_mass()
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return math.sqrt(gamma * GasConstant
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* gas.temperature() / gas.meanMolecularWeight() )
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#else:
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# raise "non-ideal not implemented."
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def isentropic(g = None):
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"""
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ISENTROPIC isentropic, adiabatic flow example
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In this example, the area ratio vs. Mach number curve is
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computed. If a gas object is supplied, it will be used for the
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calculations, with the stagnation state given by the input gas
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state. Otherwise, the calculations will be done for a 10:1
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hydrogen/nitrogen mixture with stagnation T0 = 1200 K, P0 = 10
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atm.
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"""
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if g == None:
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gas = GRI30()
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gas.set(T = 1200.0,P = 10.0*OneAtm,X = 'H2:1,N2:0.1')
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else:
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gas = g
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# get the stagnation state parameters
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s0 = gas.entropy_mass()
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h0 = gas.enthalpy_mass()
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p0 = gas.pressure()
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mdot = 1 # arbitrary
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amin = 1.e14
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data = zeros((200,4),'d')
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# compute values for a range of pressure ratios
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for r in range(200):
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p = p0*(r+1)/201.0
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# set the state using (p,s0)
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gas.set(S = s0, P = p)
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h = gas.enthalpy_mass()
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rho = gas.density()
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v2 = 2.0*(h0 - h) # h + V^2/2 = h0
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v = math.sqrt(v2)
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area = mdot/(rho*v); # rho*v*A = constant
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if area < amin: amin = area
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data[r,:] = [area, v/soundspeed(gas), gas.temperature(), p/p0]
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data[:,0] /= amin
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return data
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if __name__ == "__main__":
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print isentropic.__doc__
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data = isentropic()
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try:
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from pylab import *
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clf
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plot(data[:,1], data[:,0])
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ylabel('Area Ratio')
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xlabel('Mach Number')
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title('Isentropic Flow: Area Ratio vs. Mach Number')
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show()
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except:
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print 'area ratio, Mach number, temperature, pressure ratio'
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print data
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