Study on a layered computational model of double-sided graphite circumferential seal and the effect of grooved position

doi:10.11949/0438-1157.20241444

Abstract

Abstract:

With the development of graphite circumferential seals towards the goal of low wear and long life, the efficient and accurate solution of the performance of dynamic pressure type graphite circumferential seals with different slot structures is particularly important. This study focuses on three groove patterns of circumferential seals: rotor-grooved, stator-grooved, and double-grooved structures. A generalised transient Reynolds equation applicable to different grooving patterns is derived to solve the pressure distribution within the seal film. Dynamic mesh and finite volume methods are used in self-programming to obtain pressure distribution and performance parameters and to compare them with commercial software. Under the same groove depth conditions, the pressure distribution, lifting force, and leakage rate of the three grooving patterns are analyzed and compared over time. Furthermore, the effects of operating parameters such as rotational speed, inlet pressure, and sealing gap on the performance of the three grooving patterns are investigated. The results show that the pressure distribution obtained by self-developed programming closely matches the results of commercial software under the same mesh density. Meanwhile, the computation time is approximately 5% to 30% of that required by commercial software, indicating a significant improvement in efficiency. Compared to single-groove seals, the time-averaged lifting force and time-averaged leakage rate of double-groove seals decrease significantly. Due to the relative positional variation between the grooves on the rotor and stator surfaces, double-groove seals show periodic backflow and high-leakage fluctuations, weakening sealing and film-forming properties. The proposed layered model in this paper offers a new approach to the performance analysis of grooved circumferential seals.

Key words: circumferential seal, hydrodynamic, lift-off force, transient Reynolds equation, double-sided grooving

摘要：

随着石墨圆周密封向着低磨损、长寿命目标的发展，不同开槽结构动压型石墨圆周密封性能的高效、准确求解显得尤为重要。本文针对转子面开槽、静子面开槽和双面开槽三种开槽模式圆周密封结构，推导了适用于不同开槽模式圆周密封膜压分布求解的广义瞬态雷诺方程，基于动网格技术和有限体积法自主编程求解获得膜压分布和性能参数，并与商用软件模拟结果的求解精度和计算效率进行对比，在相同槽深条件下对比分析了三种开槽模式圆周密封的膜压分布和浮升力、泄漏率的时变特性，探讨了转速、入口压力和密封间隙等运行参数对三种开槽模式密封性能的影响规律。结果表明，相较于商用软件求解，相同面网格数下的圆周密封膜压分布自主编程计算结果吻合良好，但计算时间为5%～30%，计算效率显著提高；相较于单面开槽密封，双面开槽密封的时均浮升力和时均泄漏率均显著下降；因转子面与静子面螺旋槽相对位置变化，双面开槽密封的介质泄漏会出现反向回流和正向高泄漏周期波动的情况，弱化了密封封严特性和成膜特性。本文所提出基于广义瞬态雷诺方程的分层计算模型为不同开槽表面圆周密封的性能分析提供了新的方法。

关键词: 圆周密封, 动压型, 浮升力, 瞬态雷诺方程, 双面开槽

CLC Number:

TH 117.2

Jiayang PAN, Jinbo JIANG, Xudong PENG, Xiangkai MENG, Yi Ma. Study on a layered computational model of double-sided graphite circumferential seal and the effect of grooved position[J]. CIESC Journal, 2025, 76(6): 2886-2899.

潘嘉阳, 江锦波, 彭旭东, 孟祥铠, 马艺. 双面开槽石墨圆周密封分层计算模型及开槽位置影响研究[J]. 化工学报, 2025, 76(6): 2886-2899.

Figures/Tables 14

Fig.1 Hydrodynamic graphite circumferential seal overall structural model

Fig.2 Schematic diagram of the fluid domain model for double-sided grooved rotor and stator surfaces

Fig.3 Grid partitioning of the fluid domain for double-sided grooved seal based on commercial software

Fig.4 Changes in computational mesh for double-sided grooving

Fig.5 Geometric model of double-sided variable depth clearance

Fig.6 Numerical solution process for the pressure distribution of graphite circumferential seals

Table 1 Initial parameters for analysis of graphite circumferential seal performance

参数和单位	数值	参数和单位	数值
转子外径D /mm	66	静子周向槽宽比θ₂ /θ₀	0.5
膜厚h_m/μm	3	转子螺旋角β₁ /（°）	45
槽深h /μm	5	静子螺旋角β₂ /（°）	45
槽数	12	上游压力p_in/MPa	0.40
密封环轴向宽度l₀/mm	10	下游压力p_out/MPa	0.10
轴向槽长比l₁/l₀	0.6	转速n /(r/min)	20000
密封环周期角度θ₀/（°）	30	空气温度T /K	300
转子周向槽宽比θ₁ /θ₀	0.5	空气黏度μ /(mPa·s)	17.89

Fig.7 Simulated and calculated values of characteristic line film pressure distribution of hydrodynamic circumferential seal in different slot modes

Fig.8 Results of time-varying curve comparison between floating lift and leakage rate of a double-sided slotted circumferential seal

Fig.9 Calculation results and calculation time of single-side slotted and double-side slotted circular sealing performance under different face grid number

Fig.10 Time-varying characteristics of floating lift and leakage rate of circular seals with three grooving modes

Fig.11 The film pressure distribution diagram of the circular seal with different grooving modes

Fig.12 Floating lift and leakage rate of the circular seal under different groove depths of rotor surface and stator surface

Fig.13 Influence of operating parameters on the floating lift and leakage rate of the circular seal with three grooving modes

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