Thermo-Hydrodynamic Effect of Gas Split Floating Ring Seal with Rayleigh Step Grooves

The force equilibrium and moment equilibrium play a significant role on the sealing performance of gas split floating ring seals. A small deflection angle may generate seriously wear on sealing surface and cause seal failure. Therefore, the thermo-hydrodynamic lubrication analysis of gas split floating ring seal with Rayleigh grooves is investigated considering the deflection angle and frictional heat of surface contact, which is beneficial to grasp the hydrodynamic characteristics and rules under high-temperature and high-speed conditions. Pressure and temperature distributions of sealing rings are numerically calculated for the cases with different deflection angle, rational speed, seal pressure and ambient temperature. Then, the hydrodynamic effect and sealing performance are analyzed. The obtained results show that, the surface Rayleigh step grooves do not present obvious hydrodynamic effect when split seal ring has no deflection. While, a significant hydrodynamic effect can be obtained when the split seal ring presents a deflection angle about dozens of micro radians. Here, a 10% increase of opening force is achieved when the deflection angle reaches 80 mu rad in the case of speed 30,000 r/min and seal pressure 0.2 MPa. Moreover, the hydrodynamic effect becomes obvious with increasing deflection angle as well as rotational speed. Meanwhile, the growth of rotational speed results in an obvious increase of film temperature. The increase of ambient temperature has a significant influence on the decrease of leakage rate. When the ambient temperature increases from 340 K to 540 K, the leakage rate reduces exceeding 50%, however, it does not present obvious effect on the opening force. The proposed model has the potential to provide the theoretical basis and design guidance for surface grooves of gas split floating ring seal in the future.

Automated summary

The force equilibrium and moment equilibrium are crucial for the sealing performance of gas split floating ring seals. The deflection angle and frictional heat of surface contact are taken into consideration in the thermo-hydrodynamic lubrication analysis of gas split floating ring seal with Rayleigh grooves to understand the hydrodynamic characteristics and rules in high-temperature and high-speed conditions. Numerical calculations are performed to determine the pressure and temperature distributions of sealing rings for various conditions, and the hydrodynamic effect and sealing performance are analyzed. The results show that a significant hydrodynamic effect is achieved when a deflection angle of about dozens of micro radians is present in the split seal ring. Increasing deflection angle and rotational speed further enhance the hydrodynamic effect. The increase in rotational speed also leads to a higher film temperature. Additionally, the increase in ambient temperature significantly reduces leakage rate but has no significant effect on the opening force. This proposed model can provide theoretical basis and design guidance for surface grooves of gas split floating ring seal in the future.