NUMERICAL INVESTIGATION OF FLOW AND HEAT TRANSFER CHARACTERISTICS OF SUPERCRITICAL CO₂ IN HIGH-SPEED ROTATING ANNULUS

Focusing on the excess temperature problem of supercritical carbon dioxide (SCO₂) turbine shaft, this paper conducts a numerical investigation of flow and heat transfer characteristics with SCO₂ in the high-speed rotating annulus. The numerical method for simulation of SCO₂ Taylor–Couette–Poiseuille (TCP) flow and heat transfer is validated by existing experimental results. The key factors of Taylor vortices formation and shaft cooling performance are analyzed and discussed at the range of Ta = 1.33 × 10¹⁰–6.51 × 10¹¹. As the results show, firstly, the Taylor vortices will be generated in the annulus, which easily leads to the excitation phenomenon on turbines. The initial position of the vortex is related to axial ratio, radius ratio, Taylor number, and axial Reynolds number. Secondly, rotational and axial velocities have important influence on the global heat transfer performance compared with Taylor vortices. Finally, a correlation for SCO₂ TCP flow heat transfer is presented with effective Reynolds number and Prandtl number, and the error of the correlation is within ± 10%.