Numerical analysis of the aerothermodynamic behavior of a Hyperloop in choked flow

Abstract The Hyperloop is a form of ultra-high-speed transportation system subject to complex fluid dynamic regimes, such as choked flow. This study investigates the aerothermodynamic behavior of the Hyperloop in a choked flow structure using computational fluid dynamics (CFD). A vehicular movement model of the Hyperloop was constructed to simulate the relative motion of the pod and tube. The CFD algorithm has been previously verified via experiment data and numerical simulation. The flow structure around the Hyperloop pod and the causes of the significant temperature and pressure differences were studied. A series of complex phenomena occur in the choked region, including choked flow, shock waves, and expansion waves. The blockage ratio and pod velocity increase, widening the temperature and pressure differences across the Hyperloop tube and increasing the total temperature and pressure in the tube. The initial pressure of the tube promotes the formation of the aerodynamic environment, but has no significant effect on the temperature. Aerodynamic drag is a key performance characteristic of the Hyperloop, and the influence of three aerodynamic parameters (blockage ratio, Hyperloop pod velocity and initial tube pressure) is positively correlated with drag. With the decrease in initial tube pressure, the decrease in aerodynamic drag decelerates. Engineers could control aerodynamic drag using a low initial tube pressure and minimizing the blockage ratio, which helps improve the Hyperloop's velocity and performance.