Numerical Analysis Of Liquid Lubricated Laser Surface Textured Mechanical Seals

A laser surface textured mechanical seal (LST-MS) is a new type of hydrodynamic mechanical seals, which can run non-contact due to the hydrodynamic effect produced by micro-pores. Compared with a conventional mechanical seal, a LST-MS behaves lower friction torque, wear and temperature rise between two faces, and so has longer lifetime and higher reliability. The more important fact is that a LST-MS can be used under the extream conditions that a conventional mechanical seal can not be empolyed, such as occasions transmitting high-temperature and high-pressure water, volatile medium and so on. Therefore, a LST-MS is full of wide development prospect.A liquid lubricated LST-MS with isodiameter or nondiameter dimples is studied. Based on reasonable simplification and some assumptions, Reynolds equation is put forward for the distribution of liquid film pressure. The boundary conditions for solving Reynolds equation are determined. The mathematical models of liquid film thickness and dimple geometry, as well as the predicting methods and expressions of sealing performance are presented. Finite element method is used to resolve Reynolds equation to get fluid film pressure distribution between the two faces of a LST-MS. Then the sealing performance parameters of a LST-MS, such as opening force, liquid film stiffness, leakage, friction toque and stiffness to leakage ratio are calculated. The effects of dimple geometrical parameters and operating parameters on the sealing performance parameters of a LST-MS with isodiameter or nondiameter dimples are analyzed. Geometrical optimization of dimples onto the two types of seals is finished. The results show that a seal with nondiameter dimples performs better than a seal with isodiameter dimples under the certain conditions. The seal performance of a LST-MS with a porous sector face is analyzed, and the influence of "collect effect" is studied specifically. The size of porous sectors and the optimum micro-pore geometry parameters are presented. It is clearly that the seal performance of LST-MS with a porous sector face is superior to the fully textured LST-MS.