Design and parameter analysis of S-CO2 axial turbine blade

The supercritical carbon dioxide (S-CO₂) Brayton cycle system has the advantages of compact structure and high system cycle efficiency, which provides a solution for the current power unit to further enhance power and efficiency. The highspeed axial flow turbine serves as the sole output device in the cycle system and is a crucial component of the S-CO₂ Brayton cycle. Its operational characteristics directly influence the energy conversion and overall efficiency of the cycle system. This study employs a combined modeling and numerical calculation approach to optimize the design of the S-CO₂ axial turbine. By varying the blade structures of the stator and rotor across different speed ranges and fluid mass flow conditions, the research aims to improve the turbine performance under specific internal flow conditions. Through 35 sets of model examples, the non-linear regression analysis is carried out with pressure ratio, axial work and total isentropic efficiency as performance indicators, and three sets of mathematical models are fitted. The research results show that the turbine design parameters such as stator’s inner diameter and rotor’s outer diameter, as well as operating parameters mass flow rate and rotational speed, have various effects on the performance of the turbine, and there is a strong correlation between the blade design parameters. The research presented in this thesis offers theoretical insights that can inform the design and analysis of S-CO₂ axial turbines across various conditions and isentropic efficiencies.