Investigation of the heat exchange progress during rail cooling

Continuous welded rail is widely used on Russian railways. During maintenance operations, rail strings must be fixed at a strictly defined neutral temperature, which ensures the absence of additional thermal stresses during service. Given the limited time window for such operations, particularly in regions with hot summers, the development of methods for accelerated and controlled rail cooling is a pressing task. The aim of this study is to experimentally investigate the efficiency of forced convection from a vortex tube combined with water spraying for cooling an R65 rail to the required neutral temperature. A series of full-scale experiments was conducted on a rail segment preheated to 65 °C. Two cooling regimes were examined: natural cooling, and combined cooling using a directed flow of cold air from a vortex tube (−20 °C) together with fine water spraying (0.1 L/min). Temperature fields were monitored with a thermal imaging camera. The experimental results were verified by mathematical modeling in Solid Works. It was established that the combined method (vortex tube and water spraying) reduces the cooling time of the rail to the target temperature of 30 °C by an average of 95% compared to natural convection. The method also ensures a uniform temperature distribution across the rail section, with temperature gradients not exceeding 5 °C/mm, thereby minimizing the risk of significant residual stresses. The modeling results showed good agreement with the experimental data. The developed forced combined cooling method has proven to be efficient and holds promise for application in railway track maintenance to optimize work schedules. Its feasibility for providing the required thermal conditions for rail fastening has been scientifically substantiated. Future research will focus on optimizing system parameters, scaling the technology to full-length rails, and evaluating its economic efficiency.

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