Investigation on the similarity of turbine cascade with different working fluids

In a close Brayton cycle power system, a high-temperature gas cooled reactor (HTGR) turbine operating with specialized working fluid is the major component. Carbon dioxide and noble gases have quite different physical properties compared to air. This makes the performance evaluation methods for air turbine unable to evaluate carbon dioxide and noble gases turbines. In this paper, physical parameters of working fluid influencing turbine cascade performance are identified. The correlation of turbine cascade loss with different working fluids is investigated by using theoretical analysis and numerical validation. Special focus is on the relationship amid total pressure loss coefficient in a turbine cascade and working fluids' specific heat ratios. The results show that the correlation equation between the turbine cascade total pressure loss coefficient and the specific heat ratio of working fluid obtained in this paper can accurately predict the total pressure loss coefficient for other working fluids or in other working conditions according to the existing data. (author)