Dynamic characteristics of carbon dioxide spiral groove dry gas seal influenced by real gas effect

To accurately ascertain the influence mechanism of real gas effect on the dynamic behaviors of spiral groove dry gas seal (S-DGS), the dynamic gas film characteristics and tracking properties under three degree of freedom (3-DOF) perturbation were investigated for carbon dioxide (CO 2 ) S-DGS by semi-analytical method. The results show that CO 2 real gas effect enhances the dynamic gas film stiffness and damping. Increasing entrance pressure and compressibility number are beneficial in improving the dynamic tracking capability of stationary ring. The real gas effect of CO 2 can effectively improve the dynamic tracking ability of stationary ring, and this improving effect gradually increases with an increase in entrance pressure or speed. In addition, the improvement of tracking ability which caused by entrance pressure rising under 3-DOF perturbation is slightly suppressed at high-speed condition.