Two codes have been developed for use in the preliminary aerodynamic design of radial inflow turbines. Both use a one-dimensional approximation for the flow through the machine along with empirical correlations for estimating the losses. This is known as meanline analysis. The first code, known as RITMLD (for Radial Inflow Turbine Meanline Design Operating Point), is used to obtain the main geometric parameters of the turbine based on the required performance at the design operating point. The second code, RITMLO (for Radial Inflow Turbine Meanline Off-Design Operating Point), is then used
to predict the performance at off-design values of mass flow rate and rotational speed.
The codes were intended for use in designing the turbines for closed-cycle gas turbine engines employing super-critical carbon dioxide (S-CO2) as the working fluid. Since S-CO2 behaves as a non-ideal gas, the codes use real gas properties throughout the analysis.