Numerical methods are significant in the turbomachine design process and off-design analysis. One of these methods is the through-flow method in the meridional plane, which is utilised in an early design phase. It provides robust and quick numerical analysis of turbomachinery by only giving a few characteristic geometric parameters.

This work further develops the through-flow program tFlow by incorporating real gas equation of state (EOS), in order to verify the application of real gas EOS with the through-flow method. This allows the program to support a more reliable calculation regarding, for instance, carbon dioxide (CO₂) in a high-pressure region, where the gas does not behave like an ideal gas. The program is verified against one-dimensional (1D) solutions for the flow through a converging-diverging nozzle at different flow conditions. Furthermore, the calculation results verify the application of the Jameson-Schmidt-Turkel (JST) scheme in terms of real gas EOS. Consequently, this development brings the possibility to employ tFlow in a broader range, for example, for supercritical CO₂ (sCO₂) compressors or turbines.