Performance analysis of gas film of adaptive cylindrical seal

doi:10.11949/0438-1157.20191025

Abstract

Abstract:

An adaptive cylindrical gas film seal is proposed. Consider the problem of eccentric gas film convergence and define the abrupt change of the Rayleigh step to the gas film cycle, the relationship between the Reynold equation and the film thickness function is established, and the lubrication characteristics of friction pair are obtained. The results show that the gas bearing force is increase with speed and pressure, the leakage increases with increasing pressure but decreases with increasing speed. It is thus concluded that the internal pressure flow of the seal is dominant. Subsequently, the curved groove engraving technique is proposed, and the experiment is carried out. The results show that there are obvious scratches and wear in the chute groove, and the gas bearing force of chute groove is weaker than the straight groove, but the leakage of chute groove is smaller than the straight groove. It shows that the tangential flow of the chute groove is smaller than that of the straight groove, which results in the leakage of the chute groove is smaller than that of the straight groove. At the same time, the theoretical calculation model is agreeing well with the experimental results. The research results lay a theoretical foundation for the application of adaptive cylindrical gas film seals.

Key words: cylinder, microgroove, gas film, lubrication, experiment, friction

摘要：

提出一种自适应柱状气膜密封，构建气膜-密封环为研究对象，考虑了偏心间隙发散问题，并定义Rayleigh台阶对气膜周期的突变性，建立了气膜雷诺方程和膜厚变化函数关系式的动力润滑数值模型，获得了摩擦副气膜润滑特性，研究结果表明：气膜力随转速和压力升高而增加，泄漏量随压力升高而增加但是随转速增加而下降，说明密封内部压力流占主导地位。随后，利用曲面槽型雕刻技术，结合高速试验台对密封进行测试，结果表明：理论计算模型与试验结果吻合度较高，斜槽区域存在更多擦痕与磨损，说明斜槽浮动性弱于直列槽；但斜槽的切向流动小于直列槽，导致斜槽泄漏量小于直列槽。该研究成果为自适应柱状气膜密封的气体流动规律和应用提供了理论基础。

关键词: 柱面, 微槽, 气膜, 润滑, 试验, 磨损

CLC Number:

TB 42

Junjie LU, Wei ZHANG, Fangmin XIE, Yongfeng JIAO. Performance analysis of gas film of adaptive cylindrical seal[J]. CIESC Journal, 2020, 71(S1): 346-354.

陆俊杰, 张炜, 谢方民, 焦永峰. 一种自适应柱状密封气膜特性分析[J]. 化工学报, 2020, 71(S1): 346-354.

Figures/Tables 15

Fig.1 Schematic diagram of adaptive cylindrical gas film seal

Fig.2 Physical model of adaptive cylindrical gas film seal

Fig.3 Schematic diagram of groove structure

Table 1 Structure and gas property parameters of adaptive cylindrical gas film seal

Symbol	Structure parameter	Value	Symbol	Gas parameter	Value
R	outer radius of rotating ring	0.025 m	T ₀	ambient temperature	298 K
L	length of floating ring	0.052 m	p_l	ambient pressure	101325 Pa
C	average film thickness	5×10^-6 m	μ ₀	viscosity	1.8×10^-5 Pa·s
ε	eccentricity	0.6	ρ ₀	density	1.1452 kg/m³
n _r	rotating speed	10000—50000 r/min	p _h	gas pressure-in pressure	0—0.6 MPa

Table 2 Structure parameters of groove

Groove number

Groove

depth

Groove

length

Groove

width

Spiral

angle

Fig.4 Gas film pressure of chute groove

Fig.5 Gas film pressure of straight groove

Fig.7 Simplified diagram of groove forces

Fig.6 Variation of gas film force and leakage with speed

Fig.8 Variation of gas film force and leakage with pressure

Fig.9 Process of groove engraving

Fig.10 Schematic diagram of test bench

Fig.11 Surface scratch of rotating ring

Fig.12 Experimental and theoretical values of the leakage with speed

Fig.13 Experimental and theoretical values of the leakage with pressure

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