Aerodynamic effects on a railway tunnel with partially changed cross-sectional area

Abstract

The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section. The impact of the reduction rate of the tunnel cross-section on wave transmissions was analyzed based on the three-dimensional, unsteady, compressible, and RNG k−ε turbulence model. The results highlight that the reduction rate (S) most affects pressure configurations at the middle tunnel segment, followed by the enlarged segments near access, and finally the exit. The strength of the newly generated compression wave at the tunnel junction where the cross-section abruptly changes increases exponentially with the decrease of the cross-sectional area. The maximum peak-to-peak pressure ΔP on the tunnel and train surface for non-uniform tunnels is reduced by 10.7% and 13.8%, respectively, compared with those of equivalent uniform tunnels. Overall, the economic analysis suggests that the aerodynamic performance of the developed tunnel prototype surpasses those conventional tunnels based on the same excavated volume.

Keywords

high-speed train / railway tunnel / cross-section / transient pressure / blockage ratio

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