Non-uniform flow and heat transfer characteristics and parametric study of generator hydrogen double-flow ring seal

Abstract The double-flow floating ring seal is a key basic component to prevent crossflow between the hydrogen-cooled generator chamber and the bearing lubricating oil chamber of the hydrogen-cooled turbogenerator. Considering the relationship between lubricating oil physical properties and temperature, as well as the heat exchange between fluid domain and solid domain, the effect of oil physical property model and heat transfer model on the temperature rise and crossflow characteristics of double-flow ring seal were compared and analyzed. The quantitative characterization, formation mechanism, impact parameters and their interactive effects on the axial and circumferential non-uniform flow and heat transfer characteristics of the oil film in the sealing gap of double-flow ring seal were discussed in detail. The results show that the viscosity-temperature relationship of lubricating oil and the fluid-solid heat transfer have a significant impact on the flow and heat transfer characteristics of the ring seal. The oil flow in the sealing gap both on the air-side and hydrogen-side of the seal is closer to the adiabatic flow. Remarkble local high temperature rise region formed both at air-hydrogen section and hydrogen-side outlet, and it is sensitive to the pressure differential between oil inlet and outlet and axial length of sealing ring. The circumferential non-uniform pressure and temperature rise are mainly caused by eccentric clearance, and are highly sensitive to initial seal clearance and rotating speed. There is a strong interactive relationship among the temperature rise, crossflow and floating characteristics of the double-flow ring seal.