超临界二氧化碳向心透平设计与热流固耦合研究

In this paper, a 1 MW supercritical carbon dioxide(SCO₂)radial inflow turbine is designed to meet the requirement of a MW-class SCO₂ Brayton cycle system. The three-dimensional numerical simulation is carried out by RANS(Reynolds-averaged Navier-Stokes)equations. The off-design performance of the turbine is analyzed and the influence of the tip clearance on the efficiency is also investigated. The operation safety of the turbine impeller is analyzed with the thermal-fluid-structure coupling method. Based on the numerical simulation results and actual operating conditions of the turbine impeller, the corresponding thermal load and aerodynamic load were applied in this process. The axial force caused by the leakage flow at the backface cavity of impeller is also considered. The results show that the isentropic efficiency and the output power of turbine under design conditions are 83.53% and 1 188.57 kW, respectively. The SCO₂ turbine exhibits good off-design performance. The maximum total deformation of the turbine impeller made of titanium alloy TC4 is 0.570 mm while the maximum axial deformation is 0.303 mm. The stress of the impeller is far smaller than the material yield strength. The research results can provide basic data and theoretical support for the turbine design of MW-class SCO₂ Brayton cycle system.