Effect of turbulence model on the performance of an SCO₂ radial turbine

In this study, six turbulence models were investigated to predict the performance and flow structure in a supercritical carbon dioxide (SCO₂) radial turbine. The output power of the SCO₂ radial turbine was 13 MW. The inlet total temperature and total pressure were 800 K and 15.2 MPa, respectively. Numerical results showed that the turbulence model had a significant effect on the flow structure and performance. The Spalart–Allmaras (S–A) turbulence model induced the highest mass flow rate and the lowest efficiency. On the contrary, the SST–γ–θ turbulence model showed the highest efficiency. The total pressure distribution along the spanwise direction was also sensitive to the turbulence model. However, the total pressure deviation caused by different turbulence models was decreased along the flow direction. The turbulence model had different abilities to predict the separation both at the pressure side and suction side. It was found that the limiting streamline at suction is more sensitive to the turbulence model compared to that at the pressure side. The leakage flow also showed the different characteristics induced by different turbulence models.