Views: 2456 Author: Site Editor Publish Time: 2020-07-29 Origin: Site
At present, the seals used in industry mainly include, non contacting mechanical seals, pump seals, spring seals, elastomer bellow seals, gland packing, etc. But no matter what kind of seal, there will be shortcomings. How to further improve the performance, reliability and life of the seal is a problem that needs to be studied in the field of mechanical seal. Based on the advantages and disadvantages of previous studies, we can start from the following three points.
When the mechanical seal is in operation, the change of many factors will lead to the change of the leakage situation. For example, the constant wear of the seal boundary will affect the degree of friction and wear, and the change of the leakage channel will affect the liquid flow in the channel. The interaction between different loads will affect the friction and leakage of seal interface. When investigating the performance of mechanical seal, many factors must be considered comprehensively.
Leakage phenomenon under percolation theory is a new way to study the leakage channel between sealing interfaces. The larger the untouched area of the seal interface, the easier the leakage channel will be formed. Combined with the percolation theory, the 3D model of seal interface can be established. At the same time, the influence of porosity and pore size on the percolation probability of seal interface can be analyzed by numerical simulation method. The reason of the pore between seal interfaces can be revealed, which provides support for the systematic interpretation of the leakage mechanism of contacting mechanical seal. Although many professionals have studied the seal interface in detail, and set up the relative simulation model and calculation system, most of the models are built on the regular gap with high roughness. However, there are a large number of micro cavities and micro convex bodies on the surface of the seal interface. Because of its random and disordered characteristics, the simplified model can not be consistent with the actual situation. From the system point of view, the calculation system model of microchannel should be established.
According to the kinetic equation, the equations of motion among the fluid pressure, centrifugal force and flow resistance in the channel can be established, which are combined with the energy equation of flow resistance to obtain the governing equations satisfying the flow characteristics. The leakage channel model with optimized seal interface can be obtained by geometric analysis. According to the tortuosity of different fluid flow lines, the geometric mean and weighted mean can be taken, and the analytical expression of tortuosity of fluid flow lines in seal interface can be obtained. The direct numerical simulation model based on Fluent software can be used to study the flow velocity, flow resistance and pressure drop of the fluid in the channel between seal interfaces.
In a word, only when the basic performance of the contacting mechanical seal is studied in depth, can the friction and leakage changes in the working process be fully understood. If we want to fully understand the leakage and friction change of mechanical seal in the actual work process, we should make a professional and detailed analysis of its basic performance.