Aerodynamic Analysis and Optimization of Capsule Travelling in a Confined Tube with 3-D CFD Simulation

Wong, Lok Yen (2022) Aerodynamic Analysis and Optimization of Capsule Travelling in a Confined Tube with 3-D CFD Simulation. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

A capsule travelling in a confined tube is a typical example of tube transportation. It has been made popular recently by Elon Musk with the concept of Hyperloop, which runs the capsule in a near-vacuum tube. It has several safety and technical issues related to its low pressure condition, such as major depressurisation and leakage. In order to resolve them, it is possible to run the capsule in a tube with atmospheric pressure at a reduced speed of 200 km/h to 350 km/h. However, there is a lack of research papers on the drag force and drag coefficient of the capsule under such conditions. Besides, the internal volume of the capsule was never considered during the shape optimization and has resulted in extreme shapes such as the droplet. Therefore, the objectives of the research were to determine the total drag force and the drag coefficient of a full-scale Hyperloop capsule travelling at 70 m/s in a confined tube with an internal pressure of 101325 Pa at blockage ratios of 30%, 45%, and 60% through 3-D CFD simulation, and to optimise the shape of the full-scale Hyperloop capsule to minimise the total drag force without a significant reduction in the internal volume of the capsule. A full-scale 3-D capsule model modified from the Spartan Hyperloop team capsule was used, with an overall size of 30.48 m (L) � 4.57 m (W) � 3.81 m (H). The CFD simulation was performed with the validated SST k-omega turbulence model and dynamic meshing. The capsule was given 1s of constant acceleration to reach a travelling speed of 70 m/s. The total drag forces obtained at t = 12.5 s for the blockage ratios of 30%, 45%, and 60% are 7.065 kN, 12.638 kN, and 28.162 kN respectively, while the drag coefficients are 0.18, 0.31, and 0.7 respectively. The total drag force rose exponentially with the increase in blockage ratio. The 2-D surface response optimization was adopted with the objective of minimizing the total drag force of the capsule and the surface area of the computational domain. The reduction in drag achieved on the optimized capsule is 5.82%, with only a 0.86% reduction in internal volume. The optimized capsule features a steep nose, a high tail height, and a shortened section of maximum cross-sectional area.