Investigation on the Flow Characteristics and Sealing Performance of Dry Gas Seal at the Shaft End of Helium Compressor

The helium compressor is the core equipment of the Brayton cycle in high-temperature gas-cooled reactors, and the leakage suppression of helium working fluid at the shaft end is a key issue related to efficiency improvement. The utilization of dry gas seal with advantages such as no wear, low leakage, and non-contact is an effective approach. To investigate the flow characteristics and sealing performance of helium dry gas seal, this paper focuses on the typical spiral groove helium dry gas seal structure. Considering the influence of real gas effect, the numerical analysis is carried out to discuss the effects of structural parameters such as spiral angle, groove depth, and gas film thickness on the gas film pressure, open force and leakage. Furthermore, CO₂ and N₂ are selected to compare the flow characteristics and sealing performance with different working fluids under various inlet pressure and rotation speed conditions. The results indicate that the open force and leakage are positively correlated with the spiral angle, groove depth, and inlet pressure. As the gas film thickness increases, the open force decreases and the leakage increases. As the rotation speed increases, the open force increases and the leakage decreases for He while increases for N₂ and CO₂. Under the same operating conditions, the ranking of open force and leakage is He<N₂<CO₂. The findings of this study can provide vital reference for the design optimization of dry gas seals at the shaft end of helium compressors.