瑞利台阶型机械密封空化冷却流动湍流效应分析

doi:10.11949/0438-1157.20250654

摘要/Abstract

摘要：

机械密封高速运行时跨尺度液膜润滑流动处于湍流状态，湍流效应可显著影响液膜黏性产热与空化流动规律。为揭示该影响机制，针对瑞利台阶型机械密封建立了湍流与层流流态下的热流体动力润滑数值模型，对比分析了不同流态下的液膜流动冷却机理与规律。研究结果表明，湍流流动促进了反向台阶槽内空化的产生，削弱了液膜区涡旋流动。由于层流下湍流动能为零，在槽底根处形成流动死区，出现温度谷值区，且其液膜和端面温度明显低于湍流流态，随转速增加，二者温差更加显著。相反，湍流流动下获得更大的空化面积，对液膜和端面产生了更佳的冷却效果，同时增强了空化抽吸效应，减少了约46%的泄漏率，但负流体动压效应的增加致使开启力下降约6%。湍流效应可显著改变密封间隙内润滑介质的流动与传热过程，进而改变密封温度、压力、空化面积以及密封性能。

关键词: 高速, 机械密封, 空化流动, 湍流效应, 密封性能

Abstract:

In the high-speed operation of mechanical seals, the cross-scale lubricating film flow transitions into a turbulent state. Turbulence effects significantly influence the viscous heat generation and cavitation flow patterns within the liquid film. To reveal this influence mechanism, a thermo-hydrodynamic lubrication numerical model was developed for Rayleigh step-type mechanical seals under both turbulent and laminar flow regimes. A comparative analysis was conducted on the cooling mechanisms and flow behavior of the liquid film under different flow states. The results demonstrate that turbulent flow promotes cavitation formation in the reverse step grooves while weakening vortex motion in the liquid film region. Under laminar flow conditions, where turbulent kinetic energy is absent, a flow stagnation zone forms at the groove root, leading to a temperature trough. Both liquid film and seal face temperatures being notably lower than those under turbulence. As rotational speed increases, the temperature difference between the two regimes becomes more pronounced, reaching up to 25 K. Conversely, turbulent flow creates a larger cavitation area, resulting in better cooling of the liquid film and end faces. This also enhances the cavitation suction effect, reducing leakage by approximately 46%. However, the increased negative hydrodynamic pressure effect reduces the opening force by approximately 6%. These findings indicate that turbulence alters the flow and heat transfer processes of the lubricating medium within the sealing gap, thereby influencing seal face temperature, pressure distribution, cavitation area, and overall sealing performance.

Key words: high speed, mechanical seals, cavitation flow, turbulence effect, sealing performance

中图分类号:

TH 117

马学忠, 李聪聪, 王万龙, 陈浩. 瑞利台阶型机械密封空化冷却流动湍流效应分析[J]. 化工学报, 2025, 76(12): 6339-6350.

Xuezhong MA, Congcong LI, Wanlong WANG, Hao CHEN. Analysis of turbulence effect on cavitation cooling flow in mechanical seals with Rayleigh steps[J]. CIESC Journal, 2025, 76(12): 6339-6350.

图/表 18

图1 双列瑞利台阶型机械密封几何结构

Fig.1 Geometric structure of double row Rayleigh step mechanical seal

表1 几何及操作参数

Table 1 Geometric and operational parameters

参数名称	数值
密封环内径r_i/mm	47
密封环外径r_o/mm	57
RS主槽圆周角γ/(°)	21
RS和RRS引流槽圆周角ϕ/(°)	1.5
密封间隙h₀/μm	6
引流槽深度h₁/μm	100
RS主槽深度h₂/μm	10
RRS主槽深度h₃/μm	30
RS内径r₃/mm	54
RRS内径r₁/mm	48
进口压力p_i/MPa	0.5~2.5
空化压力p_c/kPa	30
环境压力p₀/MPa	0.1
密封介质	水

图2 网格与热边界条件

Fig.2 Grid and thermal boundary conditions

表2 THD物性参数

Table 2 THD physical property parameters

参数	数值
动环材料	不锈钢
静环材料	碳石墨
动环热导率k_r/(W/(m·K))	15
静环热导率k_s/(W/(m·K))	20
动环比热容c_r/(J/(kg·K))	500
静环比热容c_s/(J/(kg·K))	670
黏温系数α_T /K^-1	0.0175
冲洗液速度U_f/(m/s)	7
介质温度T₀/K	303.15
环境温度T_L/K	303.15

图3 网格独立验证

Fig.3 Grid independent verification

图4 模型正确性验证

Fig.4 Model correctness verification

图5 空化流动机理

Fig.5 Cavitation flow mechanism

图6 层流与湍流流动下液膜温度、压力、空化以及黏度分布对比

Fig.6 Comparison of temperature, pressure, cavitation, and viscosity distributions in liquid films under laminar and turbulent flow conditions

图7 端面1-1处截面温度、压力及液体体积分数数值对比

Fig.7 Comparison of temperature, pressure, and liquid volume fraction values at cross-section 1-1 on the end face

图8 不同转速下温度、压力及液体体积分数分布

Fig.8 Temperature, pressure and liquid volume fraction distribution at different speeds

图9 不同转速下液体体积分数及流线对比

Fig.9 Comparison of liquid volume fraction and streamlines under different speeds

图10 转速对密封性能的影响

Fig.10 The influence of rotational speed on sealing performance

图11 不同介质压力下液膜温度、压力及液体体积分数

Fig.11 Liquid film temperature, pressure and liquid volume fraction under different medium pressures

图12 不同介质压力下液体体积分数及流线对比

Fig.12 Comparison of liquid volume fraction and streamlines under medium pressures

图13 介质压力对密封性能的影响

Fig.13 The influence of medium pressure on sealing performance

图14 不同RRS主槽槽深下液膜温度、压力以及液体体积分数分布

Fig.14 Distribution of liquid film temperature, pressure and liquid volume fraction under different RRS main groove depths

图15 不同RRS主槽槽深下液体体积分数及流线对比

Fig.15 Comparison of liquid volume fraction and streamlines under different RRS main groove depths

图16 RRS主槽槽深对密封性能的影响

Fig.16 The influence of RRS main groove depth on sealing performance

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