Comparative study on leakage and film-forming characteristics of oil-gas seal with three-typical groove in a wide speed range

doi:10.11949/0438-1157.20221545

Abstract

Abstract:

How to achieve both low oil leakage at low-speed condition and low gas consumption, high stability at high speed condition is the key problem in the design of the oil-gas seal used in vehicle turbocharger. Taking the oil-gas seals with pump-out spiral groove, splayed compound groove and Rayleigh compound groove as the research object, the two-phase Reynolds model derived from the continuity of oil and gas phase is used to solve the flow field distribution of the three different types oil-gas seals numerically, and the gas film thickness and medium leakage of the oil-gas seals under different working conditions are measured based on a special-designed test platform. The leakage characteristics and film-forming characteristics of the three different oil-gas seals in a wide speed range are compared, and the influence of key structural parameters, including groove depth, spiral angle and pump-out groove length ratio, on the leakage and film-forming characteristics of the splayed compound groove oil-gas seal is emphatically analyzed. The results show that the pump-out spiral groove can be selected as the optimal scheme when oil-gas seal operates under low-speed condition because of its minimum oil leakage, and the splayed compound groove seal can be regarded as the optimal one in the high speed condition because of its significantly lower gas consumption and larger gas film stiffness. But it depends on the reasonable design of its groove depth, helix angle and pump out groove length ratio. Under certain working condition and structural parameters, the compound groove face seal is expected to form an obvious oil-gas interface on the seal face in the radial direction, so as to achieve near zero leakage for both oil and gas.

Key words: oil-gas seal, gas-liquid flow, optimal design, turbocharger, experimental validation

摘要：

如何实现涡轮增压器气膜密封在低速状态的低漏油和高速状态的低窜气、高刚度是其设计的关键问题。以泵出型螺旋槽、八字复合型槽和雷列台阶复合型槽油气密封作为研究对象，基于双相雷诺模型数值求解了三种型槽油气密封的流场分布，测试了不同工况下气膜密封的气膜厚度和介质泄漏，对比研究了宽速域范围内三种型槽油气密封的泄漏和成膜特性，重点分析了槽深、螺旋角和泵出槽长比等关键结构参数对八字复合型槽油气密封泄漏和成膜特性的影响规律。结果表明：泵出型螺旋槽密封因具有最小的漏油量可作为低速状态的优选方案，八字复合型槽密封因具有显著更低的窜气量和更大的气膜刚度可作为高速状态的优选方案，不过这依赖其槽深、螺旋角和泵出槽长比的合理设计；在一定的工况和结构参数时，复合型槽密封有望在端面形成明显的油气径向分界面，从而实现油气近零泄漏。

关键词: 油气密封, 气液两相流, 优化设计, 涡轮增压器, 实验验证

CLC Number:

TH 117.2

Wenxuan XU, Jinbo JIANG, Xin PENG, Rixiu MEN, Chang LIU, Xudong PENG. Comparative study on leakage and film-forming characteristics of oil-gas seal with three-typical groove in a wide speed range[J]. CIESC Journal, 2023, 74(4): 1660-1679.

许文烜, 江锦波, 彭新, 门日秀, 刘畅, 彭旭东. 宽速域三种典型型槽油气密封泄漏与成膜特性对比研究[J]. 化工学报, 2023, 74(4): 1660-1679.

Figures/Tables 25

Fig.1 Structural diagram of three grooved face seal with different hydrodynamic grooves

Fig.2 Mesh generation by finite volume method

Fig.3 Numerical solution flow of oil-gas seals based on two-phase Reynolds model

Fig.4 Mesh generation and boundary condition setting of computational domain

Table 1 Initial parameters adopted in the sealing performance analysis of oil-gas seal

参数	数值	参数	数值
密封面内径r_i/mm	29.5	密封间隙h₀/μm	3
密封面外径r_o/mm	37.5	外径侧压力p_out/kPa	150
槽深h_g/μm	5	内径侧压力p_in/kPa	100
泵出槽螺旋角β/(°)	20	入口油气比F_l	0.1
泵入槽螺旋角β₂/(°)	20	介质温度T/K	300
泵出槽宽比δ₁	0.5	转速n/(r·min^-1)	1000~50000
泵入槽宽比δ₂	0.5	空气黏度μ_g/(μPa·s)	17.9
泵出槽长比α₁	0.6	润滑油黏度μ_l /(mPa·s)	42.5
泵入槽长比α₂	0.2	润滑油密度ρ_l /(kg·m^-3)	886
槽数N_g	12

Fig.5 Effect of radial grid number on steady state performance and calculation time of oil-gas seal

Fig.6 Comparison of calculating time and accuracy of sealing performance between two-phase Reynolds model and VOF model under different rotating speed

Fig.7 Comparison of steady-state performance parameters of three groove oil-gas seals at different speed

Fig.8 Pressure distribution of oil-gas seals with three surface grooves

Fig.9 Flow line and oil-gas ratio distribution of oil-gas seals with three surface grooves

Fig.10 Effect of rotating speed on the steady-state performance of splayed compound groove seal at different pump outlet groove length ratio

Fig.11 Effect of pump-out groove length ratio on the flow field of the splayed compound groove seal

Fig.12 Effect of rotating speed and groove depth on the steady-state performance of splayed compound groove seal

Fig.13 Flow field distribution of splayed compound groove seal under different groove depth value

Fig.14 Effect of spiral angle on the steady state performance of the splayed compound groove seal under different rotating speed

Fig.15 Flow field distribution of splayed compound groove seal under different spiral angle value

Fig.16 Effect of changing inner pressure on the steady-state performance of splayed composite groove seal

Fig.17 Schematic diagram of oil-gas sealing performance test system

Fig.18 The state of oil absorption sponge before and after the test and its precise mass measurement

Fig.19 Structure of oil-gas seal steady state performance test platform

Fig.20 Structure diagram of rotating ring and stationary ring adopted in the test

Fig.21 Groove depth test results of pump-out spiral groove

Fig.22 Time varying curve of working condition and medium parameters during the test

Fig.23 Time varying curve of oil-gas seal parameters of three types of groove end faces during variable speed and pressure transformation

Fig.24 Oil leakage of oil-gas seal with different groove faces changing with rotating speed

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