Effects of branched tube on pressure waves in the hyperloop system: An experimental study

In this study, we experimentally investigated the aerodynamic characteristics of the Hyperloop with branch tube, an important applicational situation. Experiments were performed considering two velocities (258.6 and 295.8 m/s) and five branched angles (θ = 30°–150°) using 8.75 cm of scaled pod model (blockage ratio = 0.34). The leading shock waves LSW1 and LSW2 generated in front of the pod model were measured, and their intensity was analyzed before, on, and after the branching. The intensity of LSW1 and LSW2 at the straight tube before branching was the same as that without branching. LSW1 and LSW2 were divided by branching and propagated to the branched tube, where their intensity decreased to branched shock waves BSW1 and BSW2, respectively. The degree of decrease in BSW1 was linear as θ increased, whereas BSW2 decreased as θ and speed of the pod model increased when θ ≤ 90° and was nearly constant at 0.80 when θ ≥ 120°. The pressure characteristics near the branching were non-axisymmetric and became axisymmetric as it moved forward through the branching when x/lt ≥ 0.66. When LSW1 and LSW2 passed through the branching and were propagated as transmitted shock waves TSW1 and TSW2 after branching, their intensity decreased to approximately 86% and 91%, respectively, and was not significantly affected by the pod speed and θ.