Influence of the enlarged portal length on pressure waves in railway tunnels with cross-section expansion
| Autor: | Zhengwei Chen, Xiaoshuai Huo, Tanghong Liu, Zijian Guo, Li Li, Wenhui Li |
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| Rok vydání: | 2019 |
| Předmět: |
010504 meteorology & atmospheric sciences
Renewable Energy Sustainability and the Environment Turbulence Mechanical Engineering Aerodynamics Mechanics Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 01 natural sciences 010305 fluids & plasmas Cross section (physics) 0103 physical sciences Blockage ratio Compressibility Constant (mathematics) Pressure gradient Longitudinal wave Geology 0105 earth and related environmental sciences Civil and Structural Engineering |
| Zdroj: | Journal of Wind Engineering and Industrial Aerodynamics. 190:10-22 |
| ISSN: | 0167-6105 |
| DOI: | 10.1016/j.jweia.2019.03.031 |
| Popis: | The train/tunnel aerodynamic effects still remain a major concern during high-speed railway construction. At present, different sizes of tunnels with constant cross-section are generally adopted based on train speed and blockage ratio. However, for tunnels with constant cross-section, narrower cross-section leads to worse aerodynamic effects while larger cross-section results in sharply increasing costs. Focusing on this problem, this paper proposes a new type of high-speed railway tunnel to mitigate the aerodynamic effects by enlarging the cross-section at both ends and reducing the cross-section in the middle portion of the tunnel. A three-dimensional, unsteady, compressible and RNG k-e turbulence model is utilized to simulate the pressure waves induced by a high-speed train passing through such a tunnel. Three cases with different enlarged portal lengths are simulated. The pressure variations on the tunnel wall and train surface are compared with previous moving model tests to validate the numerical algorithm. The results show that the train-tunnel-entry induced pressure transients are greatly reduced compared with that of constant cross-section tunnel. In addition, the pressure gradient and micro-pressure wave (MPW) emitted from the tunnel exit are also considerably decreased. Due to the enlarged portal of the tunnel, pressure waves are repeatedly reflected, and a new compression wave is developed at the junction where the tunnel cross-section abruptly changes. As a result, the wave energy is dissipated, and its strength is reduced. However, it is revealed that the length of the enlarged portal has less influence on the maximum pressure gradient and the MPW. |
| Databáze: | OpenAIRE |
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