Effects of eccentricity in tube–pod arrangements on hyperloop aerodynamics

• Published in: International journal of mechanical sciences 2024-10, Vol.279, p.109505, Article 109505
• Main Authors: Kim, Jihoon, Lee, Changyoung, Le, Thi Thanh Giang, Kim, Dokyun, Won, Yoonjin, Cho, Minki, Ryu, Jaiyoung
• Format: Article
• Language: English
• Subjects: Compressible flow; Computational fluid dynamics (CFD); Extended potential flow theory; Internal high-speed flow; Shock wave; Tube–pod arrangement in hyperloop
• ISSN: 0020-7403
• DOI: 10.1016/j.ijmecsci.2024.109505

•Aerodynamic characteristics in hyperloop pod arrangements were analyzed numerically.•An extended potential flow theory was developed for accurate force prediction.•The theoretically predicted transverse force agreed well with numerical results.•The drag coefficient exhibited minimal sensitivity to different arrangements.•Eccentricity significantly affected the transverse force, peaking at Mp = 0.576. The hyperloop, proposed as an innovative tube-train system, offers numerous transportation advantages yet exhibits inherent asymmetries arising from the design of the tube and the positioning of the pod. This asymmetry results in imbalanced forces on the pod, a factor often overlooked in studies that assume an idealized tube–pod arrangement. This study conducts a numerical analysis on the influence of pod eccentricity on hyperloop aerodynamics, specifically focusing on the pod Mach number (Mp) and eccentricity ratio (ER). Utilizing an analytical model under isentropic and potential flow conditions, this study theoretically predicts aerodynamic characteristics such as drag and transverse force coefficients related to the ER for the first time. Additionally, it explores the aerodynamic characteristics of practical tube–pod arrangements, revealing the effect of variations in the local cross-sectional areas around the pod nose and tail on airflow dynamics. In the local small cross-sectional area, an increase in ER correlates with higher flow Mach numbers and decreased pressure. Conversely, in the local large cross-sectional area, the effect of ER on flow quantities is minimal. The study revealed that while aerodynamic drag remains largely unaffected by ER, variations in both ER and Mp significantly influence the transverse force in the direction closest to the tube wall. Moreover, the length of the oblique shock wave (OSW) behind the pod decreases with increased ER, with negligible effects on the leading shock wave (LSW). For a practical tube–pod arrangement, the trends in drag coefficients mirror those of idealized setups. A transverse force coefficient in the direction closest to the tube wall is noted at a pod Mach number of 0.288, with consistent patterns in the transverse force coefficient starting at a pod Mach number of 0.576. These findings provide crucial insights into the aerodynamic and aerothermodynamic characteristics of hyperloop systems, potentially guiding future design enhancements. [Display omitted]