Leakage Characteristics and Structural Optimization of Labyrinth Seals for Linear Compressors

Hu Binbin; Liu Jiayao; Ji Zhongfu; Tang Yuteng; Qin Yongfa; Li Zhaohua

doi:10.12465/issn.0253-4339.20260714001

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Leakage Characteristics and Structural Optimization of Labyrinth Seals for Linear Compressors

更新时间：2026-08-20

- Leakage Characteristics and Structural Optimization of Labyrinth Seals for Linear Compressors
- Journal of Refrigeration Pages: 1-8(2026)
- 作者机构：
  
  1.扬州大学机械工程学院扬州 225009
  2. 江苏维创散热器制造有限公司扬州 225261
- 作者简介：
  
  Li Zhaohua， male， lecturer， School of Mechanical Engineering， Yangzhou University， 86-19825307885， E-mail：zhaohua.li@yzu.edu.cn. Research fields： linear compressor， helium cryogenic throtting tefrigeration system， electric vehicle thermal management technology.
- 基金信息：
  
  the National Natural Science Foundation of China(52506032)
- DOI：10.12465/issn.0253-4339.20260714001
  CLC： TB61⁺1;TB652
- Received：14 July 2026，
  
  Revised：2026-07-25，
  
  Accepted：27 July 2026，
  
  Online First：20 August 2026，
- 稿件说明：
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胡斌斌，刘佳瑶，纪仲甫，等. 线性压缩机迷宫密封泄漏特性及结构优化研究［J］. 制冷学报，XXXX，XX（XX）：1-8.

Hu Binbin，Liu Jiayao，Ji Zhongfu，et al. Leakage Characteristics and Structural Optimization of Labyrinth Seals for Linear Compressors［J］. Journal of Refrigeration，XXXX，XX（XX）：1-8.
胡斌斌，刘佳瑶，纪仲甫，等. 线性压缩机迷宫密封泄漏特性及结构优化研究［J］. 制冷学报，XXXX，XX（XX）：1-8. DOI： 10.12465/issn.0253-4339.20260714001.

Hu Binbin，Liu Jiayao，Ji Zhongfu，et al. Leakage Characteristics and Structural Optimization of Labyrinth Seals for Linear Compressors［J］. Journal of Refrigeration，XXXX，XX（XX）：1-8. DOI： 10.12465/issn.0253-4339.20260714001.

摘要

为降低无油线性压缩机活塞与气缸的间隙泄漏，提高压缩机密封性能，本文提出一种适用于线性压缩机自由活塞间隙密封的矩形迷宫结构，建立了包含自由活塞、工作腔、活塞径向间隙及背腔结构的瞬态数值模型，以对迷宫空腔特征尺寸及空腔宽度、深度和间隔对密封性能的影响进行研究。研究结果表明：迷宫空腔特征尺寸存在最优取值，当特征尺寸为0.2 mm时，净泄漏率降至0.798%。针对单一迷宫密封结构参数进行了研究，当空腔宽度为0.2 mm、深度为0.1 mm、间隔为0.2 mm时，迷宫密封综合性能最佳。同时，本文对迷宫密封与间隙密封抑漏性能进行对比分析，结果表明：迷宫密封结构能够显著降低瞬时间隙质量流量，具有更明显的抑制泄漏损失效果，且在高压比下，该效果更为显著。在压比为6.0的工况下，迷宫密封结构的净泄漏率降低约46.52%。研究结果可为无油线性压缩机非接触密封结构设计及参数优化提供理论依据。

Abstract

Objective

Oil-free linear compressors employ a narrow clearance between piston and cylinder to achieve noncontact operation， thereby eliminating lubrication-related contamination and mechanical wear. However， the unavoidable clearance leakage reduces the volumetric efficiency and becomes increasingly severe under high-pressure conditions， thereby limiting overall compressor performance. Labyrinth seals have been widely adopted in turbomachinery and reciprocating compressors owing to their excellent leakage-suppression capability. Nevertheless， their application in oil-free linear compressors has rarely been reported， and the influence of cavity geometry on transient leakage characteristics has not been systematically clarified. In this study， a rectangular labyrinth seal was proposed for sealing the piston–cylinder clearance， and the effects of cavity geometry on sealing performance were investigated.

Method

A transient computational fluid dynamics （CFD） model was established for an oil-free Oxford-type moving-magnet linear compressor. The numerical model incorporated the compression chamber， piston-cylinder radial clearance， rectangular labyrinth seal， and back chamber， enabling simulation of the transient leakage process throughout one operating cycle. Simulations were performed at pressure ratios of 2， 3， 4， 5， and 6. The characteristic cavity size was first evaluated by assigning identical values of 0.1， 0.2 and 0.4 mm to the cavity width， depth and spacing， respectively. Subsequently， the cavity width， depth， and spacing were varied independently， whereas the remaining parameters were maintained at their reference values. The sealing performance was evaluated using the instantaneous leakage mass-flow rate， net-leakage ratio， and transient pressure， velocity， and refrigerant density distributions. Finally， the optimized labyrinth seal was compared with a conventional smooth-clearance seal under identical operating conditions.

Results and Discussion

Cavity geometry significantly influenced transient-leakage characteristics. An optimum characteristic cavity size of 0.2 mm was obtained， corresponding to a net-leakage ratio of 0.798%. Independent parametric analyses further indicated that the optimum cavity dimensions were 0.2 mm width， 0.1 mm depth， and 0.2 mm spacing， yielding a minimum net-leakage ratio of 0.668%， which decreased progressively along the leakage path because of successive throttling through adjacent labyrinth cavities. Meanwhile， the refrigerant density exhibited a layered distribution that reversed with the leakage direction during different stages of the compression cycle. The transient velocity field showed that the local high-velocity regions were primarily concentrated within the throttling gaps between adjacent cavities， whereas the low-velocity recirculation zones were maintained inside the cavities throughout the cycle. Compared with the conventional smooth-clearance seal， the proposed labyrinth seal reduced the net-leakage ratio by 46.52% at a pressure ratio of 6. Moreover， leakage suppression became increasingly pronounced as the pressure ratio increased， demonstrating the superior sealing capability of the labyrinth configuration under high-pressure ratio conditions.

Conclusion

The proposed rectangular labyrinth seal effectively suppressed clearance leakage while maintaining noncontact piston operation. An appropriate cavity geometry is essential for achieving high sealing performance. The optimized structure provided an effective sealing solution for oil-free linear compressors operating under high-pressure ratio conditions.

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references

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