典型螺旋槽端面干式气体密封动压开启性能

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The opening behavior of two sealing faces of a dry gas seal（DGS）with various types of specified grooves is very important for startup,shut down,and operation of the DGS.Based on the theory of gas mixed lubrication,a dynamic opening model for a DGS was developed by considering the effects of gaseous slip flow and surface roughness.In the present paper,the critical dynamic sealing behavior,especially the opening characteristics of three types of DGSs were studied,including the spiral-groove DGS（S-DGS）,the spiral groove and annular groove DGS（AS-DGS）,and the goose groove DGS（GS-DGS）.The gas film pressure distributions between two sealing faces of three types of DGSs under different operating conditions were numerically analyzed.A series of simulations were carried out to study the influences of annular neck length ratio,annular neck width ratio,balance ratio,spring pressure and sealed medium pressure on the critical opening rotational speed and hydrodynamic opening force ratio.Results showed that the critical opening rotational speed was directly determined by dynamic pressure effect of the specified face grooves.Dynamic opening characteristics were greatly affected by balance ratio and spring pressure,and slightly affected by annular neck length ratio.A comparison of the dynamic opening characteristics among the three types of DGSs was made under the same operating conditions.The results showed that the GS-DGS opened most quickly,the AS-DGS secondly,and the S-DGS most slowly during the startup process.型槽端面干式气体密封的开启特性对密封的启动、停车和运行具有重要实际意义。基于气体混合润滑理论,考虑密封端面粗糙度效应和端面间气体滑移流效应,建立了干式气体密封的动压开启性能分析模型。开展了螺旋槽端面干式气体密封、带内环槽的螺旋槽端面干式气体密封和雁型槽端面干式气体密封等三种典型型槽端面干式气体密封的临界动压开启性能研究,数值分析了不同工况下三种型槽密封端面气膜压力分布,研究了环颈长比、环颈宽比、平衡比、弹簧比压和密封压力对临界开启转速、动压开启力比等开启性能参数的影响规律。结果表明：端面型槽的动压效应直接决定干式气体密封的临界开启转速,平衡比、弹簧比压对密封的动压开启性能影响较大,而环颈长比影响很小;在相同操作条件下,三种型槽端面密封相比较,雁型槽端面干式气体密封最易开启,带内环槽的螺旋槽端面干式气体密封次之,螺旋槽端面干式气体密封最难开启。