As a new form of sealing structure, the diffused self-pumping hydrodynamic mechanical seal has excellent sealing performance and a wide range of application prospects. Four kinds of diffused self-pumping hydrodynamic mechanical seals with equal-section diffuser groove, divergent diffuser groove, convergent diffuser groove and circular arc diffuser groove were designed, and the comprehensive evaluation factor η
was introduced, and the comprehensive sealing performance was analyzed through Fluent numerical simulation. Based on the optimal diffuser groove structure, the structural parameters of the sealing surface through orthogonal experiments were optimized. The results showed that the equal-section diffused self-pumping hydrodynamic mechanical seal had the best comprehensive sealing performance. Within the range of test parameters, the number of spiral grooves Ng
and the outer diameter rk
of the sealing ring had an influence on the leakage rate, and the number of spiral grooves Ng
had the most significant effects. The outer diameter rk
of the sealing ring and the helix angle α
had an influence on the opening force, among which the influence of the outer diameter rk
of the sealing ring was more significant, and the opening force increased rapidly with the increase of the outer diameter of the sealing ring. According to the results of orthogonal test analysis, the structural parameters of the sealing surface were optimized, and the leakage rate obtained by the new factor level combination was as low as 0.784 361 ml/h, and the opening force was 3.958 962 kN under the condition that other boundary conditions were unchanged.