端面变形锥角对干气密封性能影响的数值模拟

The flow field analysis of most dry gas seal end faces is carried out on the assumption of parallel gap for end faces.But because of the force deformation and thermal deformation working together,the gap between the end faces of two sealing rings is almost linearly convergent.The gas film flow fields for parallel gap and convergent wedge gaps with different angles were simulated and analyzed.ANSYS is used to pretreat the gas film flow field model.For the changes of gas density and viscosity in the flow field,the user-defined function (UDF) was used to define the density and viscosity of sealing medium as pressure functions.Fluent software was used for numerical simulation of the flow field of gas film.It was found that the variable density viscosity method used is feasible for the simulation of wedge flow field for a dry gas seal.The change of the convergent angleβof gas film alteres the radial pressure profile.The pressure profile was a continuous and smooth convex curve.The peak pressure at the spiral groove root decreases obviously comparing with that for the parallel film gap.With the increase of gas film taper angle,the decreasing speed of peak pressure became slower and slower.Under the same working conditions,with the increase ofβ,the total film thickness increases,the film thickness at the inner end of the face first decreases and then increases and the film thickness at the outside diameter and leakage increases.The leakage increases obviously whenβis greater than the given value.When 0≤β≤0.000 50 rad,the relationships between film thickness and leakage rate withβwere given,respectively.It was suggested that 0≤β≤0.000 30 rad.With the increase ofβ,the dynamic pressure effect of the gas in the helical groove is weakened and the radial wedge effect between the end faces is enhances,which causes both end faces to open.