Research on friction and wear characteristics of mechanical seals in start-stop phases based on 3D fractal end-face characterization

doi:10.11949/0438-1157.20250737

Abstract

Abstract:

To address seal failure caused by face contact during start-stop phases of non-contact mechanical seals under unstable operating conditions, a fluid-solid-thermal-wear coupled model was established based on the 3D fractal characterization of micro-asperities and Archard's adhesive wear theory. The model calculates wear rate and volume of the seal faces, and its accuracy was validated experimentally. A systematic analysis was conducted on how operating pressure, temperature, rotational speed, and spiral groove structural parameters during the start-stop phase influence the contact characteristics, thermal behavior, and frictional wear of the seal faces. The results show that rotational speed and pressure significantly affect wear, while temperature influences it indirectly via thermal deformation of the seal rings. Lowering the operating pressure and temperature during the start-stop phase, starting and stopping at speeds greater than 1500 r·min^-1, and adjusting the speed in increments greater than 1000 r·min^-1 all help reduce friction and wear during the start-stop phase of the friction pair. Considering both start-stop and steady-state performance, the optimal spiral groove parameters are: dam ratio 0.7—0.8, weir ratio 0.4—0.6, spiral angle 16°—18°, 10—12 grooves, and groove depth of 6—8 μm.

Key words: mechanical seal, start-stop characteristics, attrition, fractals, fluid mechanics

摘要：

针对非接触式机械密封在启停阶段因工况不稳定发生碰磨引起密封失效的问题，基于密封端面摩擦副微凸体3D分形表征原理，采用Archard黏着磨损理论方法建立了非接触式机械密封在启停阶段的流-固-热-磨耦合模型，计算出摩擦副的磨损率和磨损量并通过试验验证了模型的准确性，分析了非接触式机械密封在启停阶段的操作压力、操作温度、操作转速以及螺旋槽结构参数对摩擦副接触特性、温升特性和摩擦磨损特性的影响规律。结果表明：启停阶段操作转速和操作压力对密封磨损率和磨损量影响显著，操作温度通过密封环的热变形间接影响磨损程度；降低启停阶段的操作压力、操作温度并以大于1500 r·min^-1转速启停、以转速增量大于1000 r·min^-1调节均有利于减少摩擦副启停过程中的摩擦磨损；综合考虑密封启停阶段和稳定工作阶段的性能得到螺旋槽结构参数的优选取值为：槽坝比0.7~0.8，槽堰比0.4~0.6，螺旋角16°~18°，槽数10~12个，槽深6~8 μm。

关键词: 机械密封, 启停特性, 磨损, 分形, 流体力学

CLC Number:

TH 117

Kaifang CHEN, Shuangxi LI, Enzhe BI, Yuhui SUN, Jupeng TIAN, Lei WANG. Research on friction and wear characteristics of mechanical seals in start-stop phases based on 3D fractal end-face characterization[J]. CIESC Journal, 2025, 76(12): 6508-6526.

陈凯放, 李双喜, 毕恩哲, 孙宇辉, 田举鹏, 王磊. 基于3D分形端面表征的机械密封启停阶段摩擦磨损特性研究[J]. 化工学报, 2025, 76(12): 6508-6526.

Figures/Tables 45

Fig.1 Schematic diagram of non-contact mechanical seal structure

Fig.2 Helical groove on stationary ring end face

Table 1 Sealing structure parameters and working condition parameters

参数	数值	参数	数值
密封端面外径r_o/mm	62.8	螺旋槽槽数N_g/个	12(6~14)
密封端面内径r_i/mm	48.8	进口压力p_in/MPa	0.6(0.1~1.0)
螺旋槽螺旋角α/(°)	15(12~20)	出口压力p_out/MPa	0.1
螺旋槽槽坝比γ₁	0.7(0.5~0.9)	介质温度T_in/℃	500(100~900)
螺旋槽槽堰比γ₂	0.5(0.1~0.9)	转速n/(r·min)	0~4000
螺旋槽槽深h_g/ μm	6(4~12)	平衡半径r_s/mm	52.0

Fig.3 Effect of groove number on sealing performance

Table 2 Measured and calculated values of rough contours

粗糙轮廓特征	密封环材料	计算值	测量值
算术平均差R_a/μm	GH4169	0.009	0.009
算术平均差R_a/μm	SiC	0.003	0.003
最大轮廓峰高R_p/μm	GH4169	0.201	0.200
最大轮廓峰高R_p/μm	SiC	0.110	0.109
最大轮廓谷深R_v/μm	GH4169	0.185	0.188
最大轮廓谷深R_v/μm	SiC	0.131	0.128
轮廓单元平均宽度R_sm/μm	GH4169	1.083	1.067
轮廓单元平均宽度R_sm/μm	SiC	0.483	0.533

Fig.4 Schematic diagram of boundary conditions

Fig.5 Geometrical model

Fig.6 Grid independence verification of fluid domain

Fig.7 Grid independence verification of solid domain

Fig.8 Schematic diagram of coupling process

Fig.9 Effect of operating pressure on contact characteristics of friction pair

Fig.10 Effect of operating pressure on temperature rise of friction pair

Fig.11 Effect of operating pressure on wear characteristics of friction pair

Fig.12 Effect of operating pressure on wear volume

Fig.13 Effect of operating temperature on contact characteristics of friction pair

Fig.14 Effect of operating temperature on temperature rise of friction pair

Fig.15 Effect of operating temperature on wear characteristics of friction pair

Fig.16 Effect of operating temperature on wear volume

Fig.17 Effect of operating speed on contact characteristics of friction pair

Fig.18 Effect of operating speed on temperature rise of friction pair

Fig.19 Effect of speed increment on friction pair wear

Fig.20 Effect of speed increment on wear volume

Fig.21 Effect of groove-to-dam ratio on contact characteristics of friction pair

Fig.22 Effect of groove-to-dam ratio on temperature rise of friction pair

Fig.23 Effect of groove-to-dam ratio on friction pair wear

Fig.24 Effect of groove-to-dam ratio on wear volume

Fig.25 Effect of groove-to-weir ratio on contact characteristics of friction pair

Fig.26 Effect of groove-to-weir ratio on temperature rise of friction pair

Fig.27 Effect of groove-to-weir ratio on wear characteristics of friction pair

Fig.28 Effect of groove-to-weir ratio on wear volume

Fig.29 Effect of helix angle on contact characteristics of friction pair

Fig.30 Effect of helix angle on temperature rise of friction pair

Fig.31 Effect of helix angle on wear characteristics of friction pair

Fig.32 Effect of helix angle on wear volume

Fig.33 Effect of groove number on contact characteristics of friction pair

Fig.34 Effect of groove number on temperature rise of friction pair

Fig.35 Effect of groove number on wear characteristics of friction pair

Fig.36 Effect of groove number on wear volume

Fig.37 Effect of groove depth on contact characteristics of friction pair

Fig.38 Effect of groove depth on temperature rise of friction pair

Fig.39 Effect of groove depth on wear characteristics of friction pair

Fig.40 Effect of groove depth on wear volume

Fig.41 High-temperature non-contact mechanical seal test rig

Fig.42 Effect of operating pressure on wear characteristics of friction pair

Fig.43 Comparison of seal dynamic ring and static ring end face morphology before and after testing

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