Influence of the Pressure-equalizing Groove on the Seal Performance of Hydrostatic Dry Gas Seal

The pressure-equalizing groove with throttling effect for the hydrostatic dry gas seal (DGS) has the ability of equalizing the gas film pressure.The performance comparison and structure optimization of the typical groove hydrostatic DGS were studied. Based on the hydrostatic gas lubrication theory, the geometric and mathematical model of the circular, ellipse, fan and annular hydrostatic DGS were established, Reynolds equation of the gas film between sealing face was solved by using the finite difference method (FDM), and the pressure distribution and steady seal performance parameters of four kinds of hydrostatic DGS were obtained. The influence of radial groove ratio and circumferential groove ratio on the performance of four kinds of hydrostatic DGS was analyzed. To achieve greater opening force and gas film stiffness, the optimum range of radial groove ratio and circumferential groove ratio of the pressure equalizing groove was obtained. The result shows that when the radial groove ratio was between 0.15 and 0.45, the annular groove DGS had greater opening force and gas film stiffness, while the optimum radial groove ratio for the rest types of hydrostatic DGS was between 0.30 and 0.45. The fan and the elliptical hydrostatic DGS had comparable working performance and their seal performance is inferior to the annular one. When the circumferential groove ratio was between 0.6 and 1.0, the fan hydrostatic DGS can obtain larger opening force and gas film stiffness.