def __init__(self, name, R, cp):
"""
Returns a PerfectGas Instance
Parameters:
R: float, specific gas constant
cp: float, heat capacity at constant pressure
"""
IdealGas.__init__(self, name, R)
self.cp = cp
self.cv = self.cp - self.R
"""
IdealGas.__init__(self, name, R)
self.cp = cp
self.cv = self.cp - self.R
def __str__(self):
return super(PerfectGas, self).__str__() + ", cp={} J/kgK".format(self.cp)
def du(self, dT):
"""
Returns the change in specific energy of the gas in J/kg
Parameters:
dT: float, temperature difference in K
"""
return self.cv * dT
if __name__ == "__main__":
a = IdealGas("air", 287)
b = PerfectGas("air", 287, 1004)
print(a)
print(b)
print("rho = {:.3f} kg/m3".format(a.density(101325, 293.15)))
print("rho = {:.3f} kg/m3".format(b.density(101325, 293.15)))
print("du = {:.2f} J/kg".format(b.du(50)))
