Aerodynamic design and numerical analysis of a radial inflow turbine for the supercritical carbon dioxide Brayton cycle

The supercritical carbon dioxide (S-CO2) Brayton cycle is considered to be one of the most promising power cycles for the future. Its main advantages include compactness, high efficiency, high safety and good environmental friendliness. The system performance depends much on the turbine, which is one of the core components of the S-CO2 Brayton cycle. Compared to the axial turbine, the radial inflow turbine has a lower cost and more compact structure, and can provide a high operating efficiency under small volume flows. In this study, a design method for an S-CO2 radial inflow turbine is proposed and a 1.5-MW S-CO2 radial inflow turbine is designed. The three-dimensional (3D) numerical simulation of the designed turbine is carried out by using ANSYS-CFX commercial software, and the results are in good agreement with the design values. The off-design performance of the turbine is predicted by using the one-dimensional (1D) model and the 3D numerical simulation. The results are consistent with each other. It means that the proposed design method for the S-CO2 radial inflow turbine is reliable.