Abstract
In order to improve the environmental adaptability and sealing performance of the rotating seal, the principles and failure mechanisms of the rotating seal in ambient pressure in deep-sea is researched. It is proposed that the excessive friction caused by the ambient pressure and the magnitude of interference is the main reason for rotating seal failure. To reduce friction effect, a combined lip seal is designed, whose structure consists of a rotating seal made of polytetrafluoroethylene (PTFE) and an O-shaped fastening ring. The finite element analysis results indicate that the contact pressure in sealing surface increases with the growing magnitude of interference, but decreases when it exceeds the value 0.65mm. A suitable range (0.5×10 m ~0.6×10m) for the magnitude of interference is concluded for this combined seal. Finally, the designed PTFE rotating seal is tested in a deep-sea imitating hull, and the experimental results show that the seal is able to work reliably without leaking for more than 10 hours in the ambient pressure less than 30MPa, and verifies the design of the rotating seal is rational, which displays that the seal is available for the special requirement of deep-sea environment in short periods.
Highlights
The rotating seal is an important sealing form of rotary device in deep sea
The sealing mechanism of rotating seals is the frictional resistance by the magnitude of interference fit with the sealing surface to block off the pressure fluid to be sealed
The O-ring has a dynamic compensation function in the lip seal, so that stable contact pressure can properly maintain between the PTFE seal lip and the rotating shaft, which is conducive to the film formation with uniform and suitable thickness and improves the sealing performances
Summary
The rotating seal is an important sealing form of rotary device in deep sea. It is often used in the motor seal under deep sea to isolate the motor body from seawater. 1874-155X/15 rotating seal ring through coupling lubrication and dynamic equations, and analyzed the dynamic behaviors and seal characteristics of spiral-groove rotary seal ring under real and step change oil filling conditions, through the establishment of dynamic friction model and global computational scheme, the stable lubricating properties were verified. A combination of rotating sealing structure applied in deep-sea is designed by using poly tetra fluoro ethylene (PTFE) as a sealing material, by depending on whose excellent characteristics to improve the sealing life, such as wide temperature range, low frictional coefficient, wide compatibility with the sealed fluid and small wear. The theoretical model which revealed rotating sealing mechanism is established, and the deformation and stress analysis of the combined rotating sealing structure are done by using finite element method. Its sealing mechanism and finite element simulation results are verified by the test of deep-sea imitating hull. It is reasonable to do the deformation and stress analysis for combined rotating dynamic sealing by using the finite element method
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