Tip clearance effects on the performance of a hundred kW-class supercritical CO2 turbine

Supercritical carbon dioxide (S-CO₂) Brayton cycle technology offers significant efficiency and environmental benefits. The turbine, a core component, critically affects system performance. In hundred-kW-class S-CO₂ turbines, the large tip clearance-to-blade height ratio significantly impacts efficiency and flow characteristics. This study combines experiments and simulations to investigate tip clearance effects.Comparison of simulation results with experimental data validates the simulation method with a maximum discrepancy of 3.3 %, confirming its reliability. The results demonstrate that under design conditions, the CFD-simulated mass flow rate is 9.67 kg/s with an isentropic efficiency of 81.5 %, while experimental results show 9.35 kg/s and 83.9 %, respectively. Further analysis of different tip clearances reveals a near-linear relationship between clearance size and turbine performance. For every 0.25 mm increase in tip clearance, the mass flow rate decreases by approximately 0.04 kg/s, and turbine efficiency declines by 1.04 %. These findings provide valuable guidance for optimizing the design of hundred-kW-class S-CO₂ turbines.