| Rotary shaft lip seal,as a key component of the stern seal of medium and large ships,has good followability and self-adaptability to ensure its stable operation in the complex marine environment,which is of great significance to improve the long-term serviceability of the stern seal.The open stern lip seal adopts air reverse air pressure balance to achieve non-contact operation between the seal lip and the rotating shaft,thus realizing "zero" leakage of seawater and long seal life.In this paper,an in-depth and systematic study of open lip seals for large shaft diameter stern is conducted to obtain better seal reliability and stability.Considering the interaction between fluid pressure and lip deformation in the contact area,the boundary conditions are reasonably applied according to the actual application of the seal structure and working conditions,and the numerical analysis model of the coupling between the solid field and the regional fluid field of the lip seal is established by using ANSYS analysis software.To investigate the sealing mechanism of open lip seal with static sealing and dynamic opening.Calculate the changes of characteristic parameters such as Mises stress,contact pressure,friction stress,friction torque and contact width of the lip seal before and after opening.The distribution of the velocity and pressure fields of the flow field and the changes of the gas and liquid phase boundaries are calculated after opening to obtain the variation law of the gas consumption.The influence of lip structure parameters,rubber material parameters and working condition parameters on the reverse pressure opening characteristics of the lip seal is studied,and the variation trends of contact pressure,contact width and radial force with reverse pressure are obtained in the reverse pressure opening process.The results show that the medium pressure has the most obvious effect on the reverse opening pressure,and the reverse opening pressure increases by 0.01 MPa for every 0.01 MPa increase in medium pressure;the effect of the front lip angle is the least obvious,and the static contact sealing performance can be improved by changing the structural parameters of the lip.The effects of medium pressure and reverse pressure on the flow field inside the inner and outer cavities of the lip were analyzed to obtain the variation laws of fluid flow rate,pressure and leakage rate.The results show that the effect of different medium pressures on the flow velocity is not significant when the lip is opened under constant pressure difference(0.01MPa)on both sides.The effect of reverse opening pressure on fluid flow velocity and leakage rate is greater when the lip opening height is in the range of 0 to 2.5 mm.For the contact state when the lip seal is not opened,the friction and wear test of rubber material is carried out to obtain the friction coefficient and surface wear of rubber material under dry wear,seawater and lubricating oil conditions,and to measure the effect of different rotational speeds on the friction and wear performance of rubber material.A large shaft diameter lip seal performance test system was built to accurately measure the lip reverse opening pressure based on the numerical variation of friction torque,and the error between the test value and the simulated calculated value was less than15%,indicating that the analysis model is accurate and reliable.The results of this paper include theoretical and experimental research on the sealing performance and opening characteristics of large shaft diameter ship stern lip seals,which can provide theoretical reference for lip structure design and rubber material selection,and improve its stability in long-term service in ship stern seal applications. |
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