Numerical Analysis of Aerodynamic Characteristics of Multi-Pod Hyperloop System

Abstract

The Hyperloop system is a new and innovative mode of transportation, in which high-speed pods move through near-vacuum tubes. In this study, a multi-pod Hyperloop system was analyzed using numerical simulations at different values of distance between the pods (i.e., 2L to 4L). The numerical simulations were conducted using an unsteady, compressible solver with the Reynolds-average Naiver Stokes model to determine the effect of distance between the pods on the aerodynamic characteristics and pressure wave behaviour in the Hyperloop system. Moreover, the aerodynamic drag and pressure wave characteristics were determined theoretically based on the quasi-one-dimensional conditions to compare them to the numerical results. The flow conditions around the pods were divided into three different flow regimes based on the speed of the pods. In the flow regime 1 ( ), the compression waves develop into normal shock waves for the second pod without the occurrence of the choking of the flow at the throat. However, no shock wave occurs for the first pod due to the interaction of the low-pressure expansion wave and high-pressure compression wave at the tail of the first pod. Moreover, increasing the distance between the pods results in smoothening of the pressure distribution around the pods. In the flow regime 2 ( ), choking happens at the throat of the second pod and an oblique shock wave starts to appear within the tail section of the pod. Moreover, no chocking is observed for the tail section of the first pod, due to the low-pressure expansion wave and high-pressure compression wave between the two pods. Increasing the distance between the pods delays the interaction of the two waves, but overall due to the highpressure value at the tail of the first pod, no shockwave phenomenon is observed. In the flow regime 3 ( ), the oblique shock wave at the tail of the second pod is swept to the larger length and finally achieves a constant pressure value. Whereas an oblique shock wave starts to appear at the tail section of the first pod. Another major change that is observed is the decrease in the drag force value with the increase in the distance between the pods at all pod speeds. Increasing the distance between the pods results in smooth interaction between the trailing oblique shock wave of the first pod and the leading normal shock wave of the second pod. This results in a lower pressure value at the tail end of the first pod and at the head of the second pod, which results in a low value of pressure difference between the head and tail sections of the pods and hence, a decrease in the total drag value. Based on this study, it is found that increasing the distance between the pods delays the pressure waves interaction which in turn results in a decrease in the total drag value.