The parametric analysis on angular vibration stability of spiral groove dry gas seal with real gas model

To accurately grasp the vibration stability of spiral groove dry gas seals (S-DGSs), the angular vibration stability thresholds of S-DGSs, which vary with the operating and structural parameters, were investigated by using carbon dioxide and hydrogen real gases as lubricants. The numerical results show that the vibration stability of the S-DGS in angular direction is independent of spring stiffness. Under the same conditions, the real gas effect enhances critical transverse moment of inertia and frequency ratio in carbon dioxide case, whereas it reduces both stability thresholds in hydrogen case. A spiral groove number N_g, land-to-groove ratio κ, and spiral angle δ that are too large or too small all contribute to an increased risk of S-DGS angular instability. By considering critical frequency ratio as the target, the optimal range of spiral groove structure parameters have been obtained by using a single factor analysis method.