Aerodynamic Design of the Hyperloop Concept

Opgenoord, Max M. J.; Caplan, Philip Claude

doi:10.2514/1.j057103

Cited by 78 publications

(52 citation statements)

References 14 publications

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“…There are two main conditions that cause drag. The first is the occurrence of choked flow, in which the Mach number reaches its critical level, and the second is the presence of shock waves, which are observed at supersonic speeds [6]. Hyperloop Alpha proposed two methods to delay the significant increases in drag caused by choked flow and shock waves [3].…”

Section: Introductionmentioning

confidence: 99%

“…Opgenoord & Caplan [6] recently attempted to optimize the Hyperloop pod design of the MIT Hyperloop team in consideration of the point of the shock wave using experimental and computational techniques. Braun et al [17] conducted three-dimensional computational simulations of the Hyperloop system with varying pod shapes, and found that drag could be reduced by a maximum of 69% compared with the optimized maximum-lift design.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis of Aerodynamic Characteristics of Hyperloop System

Kang

Ham

et al. 2019

Energies

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The Hyperloop system is a new concept that allows a train to travel through a near-vacuum tunnel at transonic speeds. Aerodynamic drag is one of the most important factors in analyzing such systems. The blockage ratio (BR), pod speed/length, tube pressure, and temperature affect the aerodynamic drag, but the specific relationships between the drag and these parameters have not yet been comprehensively examined. In this study, we investigated the flow phenomena of a Hyperloop system, focusing on the effects of changes in the above parameters. Two-dimensional axisymmetric simulations were performed in a large parameter space covering various BR values (0.25, 0.36), pod lengths (10.75–86 m), pod speeds (50–350 m/s), tube pressures (~100–1000 Pa), and tube temperatures (275–325 K). As BR increased, the pressure drag was significantly affected. This is because of the smaller critical Mach number for a larger BR. As the pod length increased, the total drag and pressure drag did not change significantly, but there was a considerable influence on the friction drag. As the pod speed increased, strong shock waves occurred near the end of the pod. At this point, the flows around the pod were severely choked at both BR values, and the ratio of the pressure drag to the total drag converged to its saturation level. At tube pressures above 500 Pa, the friction drag increased significantly under the rapidly increased turbulence intensity near the pod surface. High tube temperatures increase the speed of sound, and this reduces the Mach number for the same pod speed, consequently delaying the onset of choking and reducing the aerodynamic drag. The results presented in this study are applicable to the fundamental design of the proposed Hyperloop system.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Aerodynamic Characteristics of Hyperloop System

Kang

Ham

et al. 2019

Energies

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“…They concluded that the blockage ratio of 0.25 is efficient in terms of drag reduction at the tube pressure 1,000 Pa. A three-dimensional CFD analysis of a Hyperloop pod was first reported by Braun et al [12], who proposed a procedural system for an aerodynamic design, in which a preliminary analysis was conducted in one dimension, followed by a three-dimensional analysis for optimization. Opgenoord and Caplan presented an optimization of the Hyperloop pod developed by the team from the Massachusetts Institute of Technology (MIT) [13]. The design speed was Mach 0.3, although a transonic speed was also analyzed to evaluate the influence of the choke flow around the pod on the drag force.…”

Section: Introductionmentioning

confidence: 99%

“…Nonetheless, the CFD studies mentioned above [10][11][12]14] assumed that the whole computational domain is fully turbulent and the laminar flow and the transition were neglected. Only Opgenoord and Caplan [13] paid attention to the transition. In their two-dimensional CFD simulations, the transition was modeled with e N method [16], which is based on the linear stability theory [17].…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics simulation of Hyperloop pod predicting laminar–turbulent transition

Nick

Sato

2020

Rail. Eng. Science

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Three-dimensional compressible flow simulations were conducted to develop a Hyperloop pod. The novelty is the usage of Gamma transition model, in which the transition from laminar to turbulent flow can be predicted. First, a mesh dependency study was undertaken, showing second-order convergence with respect to the mesh refinement. Second, an aerodynamic analysis for two designs, short and optimized, was conducted with the traveling speed 125 m/s at the system pressure 0.15 bar. The concept of the short model was to delay the transition to decrease the frictional drag; meanwhile that of the optimized design was to minimize the pressure drag by decreasing the frontal area and introduce the transition more toward the front of the pod. The computed results show that the transition of the short model occurred more on the rear side due to the pod shape, which resulted in 8% smaller frictional drag coefficient than that for the optimized model. The pressure drag for the optimized design was 24% smaller than that for the short design, half of which is due to the decrease in the frontal area, and the other half is due to the smoothed rear-end shape. The total drag for the optimized model was 14% smaller than that for the short model. Finally, the influence of the system pressure was investigated. As the system pressure and the Reynolds number increase, the frictional drag coefficient increases, and the transition point moves toward the front, which are the typical phenomena observed in the transition regime.

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“…Since the first modern proposal in 2013, the concept of a Hyperloop system has morphed into many different variations, from small-scale prototypes fielded at the academic/industrial annual competition sponsored by SpaceX in its specially built 1.5km track (e.g., [3]) to the large-scale industrial prototypes that are expected to be operational within a decade (e.g., [4,5]). A number of studies examined the main issue of aerodynamic drag, and how it affects the Hyperloop pod motion inside the tube under different pressure conditions, using all possible approaches, from analytic calculations [6] to computations in two and three dimensions [7][8][9]. Reference 6 was one of the first studies to examine the pod aerodynamics and the specific issue of compressible flow around the Hyperloop system at high speeds using a one-dimensional analytic approach; its conclusion was somewhat negative, insofar as the study showcased the difficulty of achieving high pod speeds inside a tube, and brought forth the need for internal fans/compressors that would mitigate some of the challenges presented by aerodynamics.…”

Section: Introductionmentioning

confidence: 99%

Levitation Methods for Use in the Hyperloop High-Speed Transportation System

2019

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The Hyperloop system offers the promise of transportation over distances of 1000 km or more, at speeds approaching the speed of sound, without the complexity and cost of high-speed trains or commercial aviation. Two crucial technological issues must be addressed before a practical system can become operational: air resistance, and contact/levitation friction must both be minimized in order to minimize power requirements and system size. The present work addresses the second issue by estimating the power requirements for each of the three major modes of Hyperloop operation: rolling wheels, sliding air bearings, and levitating magnetic suspension systems. The salient features of each approach are examined using simple theories and a comparison is made of power consumption necessary in each case.

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Aerodynamic Design of the Hyperloop Concept

Cited by 78 publications

References 14 publications

Numerical Analysis of Aerodynamic Characteristics of Hyperloop System

Numerical Analysis of Aerodynamic Characteristics of Hyperloop System

Computational fluid dynamics simulation of Hyperloop pod predicting laminar–turbulent transition

Levitation Methods for Use in the Hyperloop High-Speed Transportation System

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