Experimental study on propagation characteristics of normal shock waves through branched tube in Hyperloop system

Hyperloop is a new concept of high-speed transportation that travels through magnetic levitation and LSM propulsion system and is characterized by minimizing aerodynamic drag by traveling inside an evacuated tube. Recently, conceptual models of various infrastructure facilities based on the evacuated tube have been presented, and it is expected that the pod will experience sudden changes in blockage ratio(A_pod/A_tube) due to various structures, such as branches, cavities while traveling inside the evacuated tube at high speed. In order to study the aerodynamic phenomenon caused by the bifurcation of the evacuated tube, a 1/15 small-scaled Hyperloop aerodynamic test rig was used to test the driving of the pod model on a test section with a 30° of side branched tube. The driving test was performed in the range from 250m/s to 320 m/s of pod speed at approximately 1/1000 atm, and the normal shock waves before and after the branching section were measured using KULITE pressure sensors (XT-140-5A). As a result, the normal shock wave is formed in front of the pod model and reaches the branching section first, and the propagation behavior changes to a complex two-dimensional propagation as it passes through the branched part. It is also confirmed that the transmitted shock wave is divided into the branching and straight direction, respectively, and the shock wave intensity in the straight direction is shown to decrease by 11.3% before and after the branching section at the pod speed of about 320 m/s.