DESIGN AND ANALYSIS OF COOLING STRUCTURE FOR DRY GAS SEAL CHAMBER OF SUPERCRITICAL CARBON DIOXIDE TURBINE SHAFT END

Dry gas seal is a kind of non-contact mechanical seal that offers lower leakage and longer operating life comparing to conventional seals. Due to its low leakage rate, a dry gas seal is used to control the leakage flow through the clearance between the stationary and rotational components of Supercritical Carbon Dioxide (SCO2) turbomachinery, especially at the shaft end of the SCO2 compressor and turbine. However, the high inlet temperature of the SCO2 turbine makes the SCO2 dry gas seal face a severe operation condition. The chamber temperature, cooling effects, and the deformation of the rotating ring of a newly designed external flush structure are numerically investigated using the fluid-thermal-solid coupling approach in this paper. Within the same cooling flow rate, the current study analyzed the effect of six external flush cooling arrangements on these parameters. The obtained results demonstrate that the designed tangential admission cooling structure has the best cooling performance which can decrease the temperature by 400K in the film region and 440K in the chamber region. In addition, the deformation of the rotating ring decreases by 50% under this cooling structure by comparing the no cooling design. The present work provides the reference for the chamber cooling structure design of the SCO2 dry gas seal.