Mechanism of Wheel-Rail Adhesion Recovery During Large Sliding Processes Under Water Lubrication Condition

• Published in: Tribology transactions 2024-11, Vol.67 (6), p.1232-1251
• Main Authors: Zhou, Jiajun, Tian, Chun, Ma, Tianhe, Zhai, Gengwei
• Format: Article
• Language: English
• Subjects: adhesion recovery; adhesion test; Adhesion tests; Braking; large sliding; Lubrication; Recovery; Rolling contact; Sliding; Water temperature; Wheel rail contact
• ISSN: 1040-2004; 1547-397X
• DOI: 10.1080/10402004.2024.2415476

The challenge of low adhesion between the wheel and the rail constrains the advancement of train braking technologies, resulting in sliding during braking, increased braking distances, and even operational safety incidents. Low adhesion arises from the contamination of the rail surface by a third body, such as water or oil, significantly reducing adhesion. However, experimental studies have found that wheel-rail adhesion coefficient under water lubrication conditions possesses recovery capability. In scenarios characterized by low adhesion in water lubrication conditions, a secondary rise in adhesion occurs when substantial wheel-rail sliding is present. This paper focuses on numerically modeling the unique phenomenon of adhesion recovery during large-sliding processes under water lubrication conditions. Considering the notable differences in frictional heating during wheel sliding, as opposed to pure rolling conditions, we construct a wheel-rail contact model under mixed lubrication conditions that incorporates the solid-liquid coupled heat transfer effect. This model achieves stable solutions for the wheel-rail contact relationship and the temperature at the wheel-rail interface. The impacts of velocity, axle load, water temperature, and slide ratio on the adhesion recovery phenomenon are discussed, revealing the underlying mechanism of adhesion recovery during large sliding processes. Finally, brake adhesion tests under water lubrication conditions are conducted on a scaled test rig to validate the proposed theoretical model.