In order to further improve the sealing performance of bidirectional dry gas seal, a fir tree-groove dry gas seal with radial orderly micro-structure at the bottom of hydrodynamic groove was designed. Based on the theory of gas lubrication, a 3D gas film model was established and Fluent software was used to simulate the steady flow of gas film. The performance parameters (opening force,Fo, and ratio of opening force to leakage,Fo/Q) of fir tree-groove dry gas seal with or without micro-structure were compared and analyzed under different structures and working conditions. The results showed that the orderly micro-structure design can enhanceFoat low speed, which is helpful to solve the problem that dry gas seals are prone to wear during start-up and shut-down, and the improvement effect is more significant when the groove depth is small; The existence of the micro-structure can reduce air flow oscillation and improve operation stability; The performance is the best when the width of micro-structure equals to the space,Bm/Cm=1. When film thickness,δis 2 μm, the depth of micro-structure,εof 1.0～1.3 μm can makesFo/Qgood and the laser processing efficient; when the pressure difference between inlet and outlet (?P) is large, theFoandFo/Qcan be enhanced more effectively; The existence of micro-structure hardly affects the general rules of the effect ofδ,hg,Nand ?Pon of the fir tree-groove dry gas seal.
