The Influence of Structure Parameters of Spiral Groove on Dynamic Characteristics of Dry Gas Seal

The perturbation film pressure governing equations of spiral groove dry gas seal (S-DGS) were presented by perturbation method based on gas lubrication theories, and the influence of structure parameters of spiral groove on dynamic force coefficients were analyzed in the condition of high-speed and high-pressure. The motion equations of flexibly mounted stator for analyzing the gas film thickness disturbance were presented when the rotor runout and misalignment were taken into consideration. With the combination of axial and angular gas film disturbance, the peak of film thickness disturbance on whole seal face and the disturbance stability time as objective functions for optimizing the structure parameters of spiral groove was put forward to represent dynamic tracking property of DGS. The results show that, at the different high-pressure conditions, excellent dynamic tracking property could be obtained for the S-DGS when the groove-to-land ratio was between 0.9 and 1.5, the groove-to-dam ratio was between 1.8 and 2.4, the spiral angle was between 15° and 24°, the groove depth was between 6 μm and 8 μm. The main dynamic stiffness coefficients had a more important influence on dynamic tracking property compared with other dynamic force coefficients.