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<p>Wheel-rail adhesion is a core factor ensuring the safety of traction and braking systems in metro trains. Its performance degrades rapidly in wet tunnel environments due to the formation of water films on the rail surface, which directly threatens the safety of train operations. Conventional methods (such as mechanical grinding) risk rail damage, while non-contact supersonic dewatering is limited by high-pressure gas’s space and energy demands, hindering engineering application. To overcome the above bottlenecks, this study integrates quasi-one-dimensional isentropic compression theory with CFD simulations to establish a design methodology for train-mounted supersonic airflow cleaning systems (covering gas supply and nozzle design). It uses large eddy simulation (LES) to analyze flow fields and builds an experimental platform for verification. This "theoretical modeling-numerical simulation-experimental verification" scheme overcomes prior limitations. The results show that when the compression power ratio (<i>R</i><sub>C</sub>) increases from 0.2 to 1.0, the wheel-rail adhesion coefficient increases significantly by 20.9%. Moreover, when <i>R</i><sub>C</sub> exceeds 0.4, the increase in the adhesion coefficient gradually weakens (diminishing marginal benefits). At the same time, when <i>R</i><sub>C</sub> &gt; 0.4, the uniformity of the rail surface flow field remains at a satisfactory level. By adjusting the <i>R</i><sub>C</sub> value, the volume and energy consumption of on-board equipment can be reduced while ensuring the water film removal effect on the rail surface, breaking through the engineering limitations of existing technologies, providing a validated solution for metro safety in humid regions like the Middle East.</p>

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Analysis of the Effects of Inlet Flow Heating Conditions on Wheel-Track Adhesion Performance Using Supersonic Nozzle

  • 期刊论文

  • 发表日期：

    2025年11月10日

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  • Beikun Wang,
  • Yaohui Lu,
  • Hongxing Zhao,
  • Yang Liu,
  • Jinpeng Wang,
  • Rongsheng Mao,
  • Dejun Chen

摘要

Wheel-rail adhesion is a core factor ensuring the safety of traction and braking systems in metro trains. Its performance degrades rapidly in wet tunnel environments due to the formation of water films on the rail surface, which directly threatens the safety of train operations. Conventional methods (such as mechanical grinding) risk rail damage, while non-contact supersonic dewatering is limited by high-pressure gas’s space and energy demands, hindering engineering application. To overcome the above bottlenecks, this study integrates quasi-one-dimensional isentropic compression theory with CFD simulations to establish a design methodology for train-mounted supersonic airflow cleaning systems (covering gas supply and nozzle design). It uses large eddy simulation (LES) to analyze flow fields and builds an experimental platform for verification. This "theoretical modeling-numerical simulation-experimental verification" scheme overcomes prior limitations. The results show that when the compression power ratio (RC) increases from 0.2 to 1.0, the wheel-rail adhesion coefficient increases significantly by 20.9%. Moreover, when RC exceeds 0.4, the increase in the adhesion coefficient gradually weakens (diminishing marginal benefits). At the same time, when RC > 0.4, the uniformity of the rail surface flow field remains at a satisfactory level. By adjusting the RC value, the volume and energy consumption of on-board equipment can be reduced while ensuring the water film removal effect on the rail surface, breaking through the engineering limitations of existing technologies, providing a validated solution for metro safety in humid regions like the Middle East.