Approximately analytical solutions of thermal-mechanical coupling flow field in spiral-grooved dry gas seals
Ding Xuexing1, Su Hong1,2, Zhang Haizhou1, Zhao Fang1, Zhang Weizheng1
1.College of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China; 2.Department of Mechanical Engineering, Liaoning Metallurgical Vocational and Technical College, Benxi, Liaoning 117022, China
Abstract：To study flow characteristics in the gap of a spiral-grooved dry gas seal that is subject to irregular deformation caused from external forces under high speed and pressure operating conditions, a set of analytical solutions for deformation of sealing ring and gas film thickness are obtained when the ring is underwent either a mechanical force or a thermal load. Then an approximately analytical solution for the gas film thickness is got when the seal is in the thermal-mechanical coupling state by placing the deformation due to the mechanical force upon that because of the thermal load. Based on that solution, a theoretical leakage flow rate through the gap is derived. At last, the theoretical leakage flow rates are compared with their experimental values in four cases, that is without any deformation, with thermal deformation, with mechanical deformation and with thermal-mechanical coupling deformation. The results show that the leakage flow rate increases with increasing pressure. In the case with the mechanical deformation, the predicted leakage flow rate is larger than the experimental value. The lea-kage is not only less than the experimental value but also shows a larger error against the experiment in the case with the thermal deformation. Comparing with the other cases, the error of leakage flow rate between prediction and measurement is the smallest in the case with the thermal-mechanical coupling deformation. For the application in engineering, the proposed method that considers the thermal-mechanical coupling deformation can provide a theoretical basis for spiral groove structure optimization, and then the objective that controls the leakage flow rate can be achievable.
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