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An approximately analytical method of characteristics of spiral groove dry gas seals under slip flow conditions |
Song Pengyun, Zhang Shuai |
Faculty of Chemical Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China |
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Abstract The film of dry gas seal is very thin at low speed, and the micro-scale effect slip flow has great influences on dry gas seals. In order to calculate the performances of dry gas seals at low speed, the spiral groove dry seals were taken as an example, and the effective viscosity coefficients equation was used to modify the pressure controlled equation from Muijderman′s spiral narrow groove theory. The modified equation was solved in order to find the influence law of different slip flow models to dry gas seals′ opening force, leakage rate and film stiffness. The result from above equation is compared with the result from the finite element method under different shaft speeds and film thicknesses. The comparison indicates that the results of opening force, leakage rate and film stiffness based on the approximately analytical method quite close to the results from the references. When the gas film thickness is 0.6-1.2 μm at the same shaft speed, the opening force and film stiffness decrease while increasing the film thickness. The opening force, leakage rate and film stiffness increase with the increasing shaft speed. The result of different slip flow models are basically in coincidence.
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Received: 03 March 2014
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