Study On The Effect Of Structural Parameters Of Dry Gas Seals On The Performance Of The Radial Inflow Turbine

With the development of industrial technology and people’s awareness of environmental protection, People’s requirements of industrial sealing are more stringent. Then the dry gas seal technology is introduced. Dry gas seal is a kind of fluid dynamic pressure type non-contacting mechanical seals and belongs to the mechanical seal surface reshaping technology. Its appearance has solved the problem that long mechanical seals couldn’t keep dry running for a long time. Dry gas seal has many advantages such as no surface abrasion, low power consumption, long life, simple structure, low leakage and so on. At present, the basic research abroad of dry gas seal is relatively mature, and has been widely used in the petrochemical industry. But the research of dry gas seal in our country started late, and there is a big gap compared with foreign countries. The dry gas seal products in our country mainly rely on imports. Therefore, carrying out the dry gas seal technology research has a very important meaning and value to improve our overall level of sealing technology.In this thesis, the performance of dry gas seal is studied base on the radial inflow turbine for low temperature waste heat power generation system. The main contents and conclusions are as follows:(1) On the basis of the analysis of the works, the forces, the main structural parameters and performance parameters of spiral groove dry gas seal, it introduces the concept of axial stiffness-leakage ratio as a comprehensive evaluation indicator of the spiral groove dry gas seal sealing performance. Dry gas seal structure of the radial inflow turbine for low temperature waste heat power generation system is designed based on the experience range of structural parameters and formulas, referring to the existing spiral groove dry gas seal.(2) Using the software Solidworks to build a three-dimensional model of the Spiral Groove Dry Gas Seal film. The pressure distribution of the flow field, leakage and stiffness are researched and simulated by the software Fluent. The simulation results with published experimental results are compared to prove the correctness of the simulation method.(3) Dry gas seal of the radial inflow turbine is simulated by changing the structure parameters. Then the performance parameters of dry gas seal such as leakage, opening force are obtained and the impact of dry gas seal structure parameters on sealing performance are analyzed.The results show that: The number of grooves has no effect on sealing performance of the spiral groove dry gas seal, and the effects of the groove-ridge width ratio, the groove-dam length ratio, the film thickness and the groove depth are great on the sealing performance. Spiral groove dry gas seal sealing performance is optimal when α=15°, λ=0.4, γ=0.5, hg=2μm. The film thickness is smaller the spiral groove dry gas seal sealing performance is better. but considering the actual situation, taking 1μm as the optimal value of the film thickness(4) Several different structures of groove are built and simulated. The pressure distribution between the seal faces and the sealing performance parameters such as opening force, leakage and axial stiffness are analyzed and compared. The results show that: Opening force of the spiral groove is largest, and leakage is small. Axial stiffness and axial stiffness-leakage ratio are relatively large. Various performance parameters of the spiral groove are relatively good for most of the dry gas seal. Various performance parameters of tail spiral groove are relatively moderate and lower than the spiral groove. Its structure is more complex, so comprehensive performance of tail spiral groove is worse than spiral groove. Axial stiffness and axial stiffness-leakage ratio of the link spiral groove are largest. Its opening force and leakage are relatively large. So the link spiral groove is suitable for the occasion which has less demanding on the leakage and relatively high stiffness requirements. Double spiral groove has the minimal opening force, stiffness and axial stiffness-leakage ratio. So its anti-jamming capability is weak, but the leakage of double spiral groove is much less than other grooves, and its the performance parameters are less affected by the speed. It is suitable for the occasion which has more stringent requirements on the leakage.