Hydrostatic structural parameters optimization of regulatable gas lubricated seal

Because of the significant influence of hydrostatic effect on the sealing performance of a regulatable gas lubricated seal(R-GLS), optimization of hydrostatic structural parameters of this type of seal was conducted. Based on the gas lubricated theory, Reynolds equation of the gas film between sealing rings was solved by using the finite element method(FEM). The pressure distribution of the gas film was obtained. The sealing performance, including balance gas film thickness, gas film stiffness, leakage rate and frictional loss of the seal were studied by varying hydrostatic structural parameters of R-GLS at different rotating speeds. The hydrostatic structural parameters were optimized. Analysis of sealing performance of hydrostatic gas lubricated seal(H-GLS), pumping-out gas lubricated seal(Po-GLS) and pumping-in gas lubricated seal(Pi-GLS) was made under the same operating conditions. Optimal working performance, including sealing ability, gas film stability and frictional loss could be achieved for a R-GLS when diameter of restrictive orifice was between 0.05 mm and 0.2 mm, dimensionless pressure equalizing groove depth was between 0.005 and 0.015 and dimensionless pressure equalizing groove width was between 0.02 and 0.05. Great working clearance and sealing ability could be achieved when dimensionless radius position of orifice was between 0.3 and 0.6, while excellent gas film stability could be achieved when dimensionless radius position of orifice was between 0.1 and 0.3 or between 0.55 and 0.7. Compared to H-GLS and Pi-GLS, Po-GLS was good with excellent axis gas film stiffness and balance gas film thickness, especially low leakage rate. Pi-GLS could realize zero outward leakage-rate of the regulative gas with rational design.