Error in Value of Gamma
 

I am currently modelling a steam turbine LP last stage in Fluent. I have been provided with a Cp, Thermal Conductivity and Viscosity from existing data (used in custom software) which I've input into the water-vapor material database entry in Fluent. I've calculated my gamma should be about 1.32 for steam and using ideal gas and setting Cp, Thermal Conductivity and Viscosity as constant, my gamma comes out at about 1.12 for my converged Fluent solution with the correct mass flow rate.

As I've been provided with temperature, total pressure and flow angle profiles at inlet and exit I am curious to know how Fluent calculates gamma in order for there to be such a significant discrepancy.

Any suggestions would be greatly appreciated.