Aungier's Modified RedlichKwong Real Gas Equation Of State
Many of the CompAero & TurbAero aerodynamic design and analysis programs feature a very general equation of state for ideal and nonideal fluids and fluid mixtures developed by Ron Aungier. This model is a modified form of the popular twoparameter RedlichKwong equation of state extended to include the effects of accentric factor and criticalpoint compressibility factor. It also employs generalized models for twophase (liquidvapor) fluids to handle condensing fluids in turbines.
The gas property data required for this equation are:

Molecular weight

Critical temperature

Critical pressure

Crirtical compressibility factor

Accentric factor

A polynomial expression for lowpressure specific heat (Cp) as a function of temperature
All of these gas property data are readily available for most compounds of interest from several standard publications (e.g., Yaws, C. L., Chemical Properties Handbook, McGrawHill, 1999). Both CompAero and TurbAero offer this equation of state in two standalone programs for user convenience as well as in the various design & analysis programs.

Program RKMOD: an ideal/nonideal fluid equationofstate package for a variety of thermodynamic property calculations.

Program GASDATA: a gas property database maintenance program to support Program RKMOD and the other programs that use its equation of state (including a current database of over 100 compounds).
This equation of state is described in:
(Aungier, R. H.) "A Fast, Accurate Real Gas Equation Of State for Fluid Dynamic Analysis Applications", Transactions of the ASME, Journal of Fluids Engineering, June 1995, pp. 277281. Also in Contributed Papers In Fluids Engineering 1994, ASME FEDVol. 182, 1994, pp. 16
(the original reference).
(Aungier, R. H.) Turbine Aerodynamics: AxialFlow and RadialInflow Turbine Design and Analysis, ASME Press, 2006
(this reference includes the most complete description of the general twophase flow models).
(Aungier, R. H.) AxialFlow Compressors: A Strategy for Aerodynamic Design and Analysis, ASME Press, 2003.
(Aungier, R. H.) Centrifugal Compressors: A Strategy for Aerodynamic Design and Analysis, ASME Press, 2000.
(Aungier, R. H.) "Thermodynamic State Relations," The Handbook Of Fluid Dynamics (Johnson, R. W., editor), by CRC Press LLC, 1998
pp. 429 to 434.