Coupling lubrication model of porous mechanical seal and seal performance analysis

doi:10.11949/0438-1157.20220845

Abstract

Abstract:

Considering the mass transfer coupling relationship between the seepage of the sealing fluid in the porous material and the liquid film, the hydrostatic lubrication model of the porous mechanical face seal was developed. The finite element method was applied to solve the lubrication equation of liquid film and the seepage governing equation of fluid in the porous material. The effects of parameters such as film thickness, permeability, and geometrical parameters of porous ring on the sealing performance were investigated. The mechanism of porous mechanical face seals was revealed. The results show that the porous mechanical face seal can form lubrication film in the seal gap due to the hydrostatic effect. Compared with ordinary parallel end face seals, its liquid film bearing capacity and axial stiffness are greater. As the permeability of porous matrix increases, the leakage rate and opening force of the seal increase gradually, while the stiffness of the liquid film gradually decreases. The increase of film thickness will lead to the increase of leakage rate and the decrease of opening force, while the liquid film stiffness first increases and then decreases, and the maximum stiffness under different permeability corresponds to different film thickness. The present results can provide new ideas and theoretical guidance for the engineering design of porous mechanical face seals.

Key words: porous mechanical face seals, hydrostatic effect, finite element method, hydrostatic lubrication, sealing performance

摘要：

考虑多孔质材料内密封介质渗流与密封端面润滑液膜间的传质耦合关系，建立了一种多孔质机械密封的流体润滑模型，采用有限单元法求解液膜润滑方程和多孔质内部渗流控制方程，研究了膜厚、渗透率、多孔质环几何参数对密封性能的影响规律，揭示了多孔质机械密封的工作机理。结果表明：多孔质机械密封依靠流体静压效应在密封端面成膜，相较于普通平行端面密封，其液膜承载力和轴向刚度更大；随多孔质渗透率的增大，多孔质机械密封泄漏率和开启力逐渐增大，而液膜刚度逐渐减小；液膜厚度的增大会导致泄漏率的增大和开启力的减小，而液膜刚度先增大后减小，且不同渗透率下的最大刚度分别对应不同的膜厚值。研究结果可为多孔质机械密封的工程设计提供新的思路和理论指导。

关键词: 多孔质机械密封, 静压效应, 有限元法, 流体润滑, 密封性能

CLC Number:

TH 117.2

Xiangkai MENG, Lingchao MENG, Yi MA, Jinbo JIANG, Xudong PENG. Coupling lubrication model of porous mechanical seal and seal performance analysis[J]. CIESC Journal, 2022, 73(10): 4576-4584.

孟祥铠, 孟令超, 马艺, 江锦波, 彭旭东. 多孔质机械密封耦合润滑模型与密封性能分析[J]. 化工学报, 2022, 73(10): 4576-4584.

Figures/Tables 9

Fig.1 Geometric model of porous mechanical face seal

Fig.2 Validation of numerical model and method

Table 1 Calculation parameters

Parameter	Value
inner radius, r_i/mm	34.0
outer radius, r_o/mm	40.0
inner radius of porous material, r_p/mm	34.5~39.5
thickness of porous material, h_p/mm	1.0~9.0
width of porous material, b/mm	0.5~5.5
film thickness, h/μm	0.5~4.5
permeability, k/m²	1×10^-15~1×10^-12
dynamic viscosity, μ/(Pa∙s)	2.2818×10^-4
outer pressure, p_s/MPa	0.50
inner pressure, p_a/MPa	0.10

Fig.3 Schematic diagram of tapered mechanical seal and performance comparison

Fig.4 Pressure and velocity vector distribution in porous matrix

Fig.5 Film pressure distribution at different permeability

Fig.6 Influence of film thickness on sealing performance at different permeability

Fig.7 Influence of porous ring thickness on sealing performance at different permeability

Fig.8 Influence of porous ring width on sealing performance at different permeability

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