Numerical study on the aerothermal characteristics in the vacuum tube transportation system

• We study the dynamic aerodynamic thermal characteristics of the vacuum tube transportation system • The generation of the shock waves and blockage effect intensify aerodynamic heating • The reflected compression wave increases the temperature around the head train by 172% • The piston wind repeatedly strikes the vacuum tube end causing sudden temperature variations • The result of this study can guide reference for subsequent field experiments The vacuum tube transportation system will be essential in the future global economy. However, the thermal environment inside the vacuum tube is complex during train operation. This study establishes a numerical calculation model of the vacuum tube train based on an under-construction model test platform. The aerothermal characteristics of the vacuum tube train are researched during uniform acceleration, uniform motion, uniform deceleration, and static processes. The results show that the aerothermal phenomena generated by trains are significant in each process. During uniform acceleration, aerodynamic heating induced by the blockage effect generates a high-temperature region at the train head. The temperature at the train rear fluctuates significantly due to the influence of shock and expansion waves. During the uniform motion process, the normal shock waves generated by the head train continuously raise the temperature of the blockage region and increase the temperature gradient. The maximum air temperature inside the tube appears at the stagnation point of the head train, peaking at 132.2°C. And the maximum temperature of the train surface is 125.5°C. During uniform deceleration, shock waves in front of the head train progressively dissipate, the high-temperature region diminishes, and the maximum temperature declines. During the static process, the air within the tube oscillates back and forth due to the effects of the piston wind, and the position of the maximum temperature inside the tube constantly changes. After two hours of stationary conditions, the average temperature within the vacuum tube rises to 28.29°C, which is 1.44°C higher than the initial temperature.