Impact of the windbreak transition on flow structures of the high-speed railway and mitigation using oblique structure and circular curve structure transition

PurposeThis paper aims to investigate the variations in the flow fields induced by transition regions in the windbreak structures between the flat ground and the cutting along a railway and to propose mitigation measures to improve the windproof ability of the windbreak. Design/methodology/approachThe improved delayed detached eddy simulation method was used to simulate the impact of the windbreak transition on flow structures of the high-speed railway under different wind angles, and also the accuracy of the numerical results was validated with those of the wind tunnel test. FindingsThe results showed that the original windbreak transition region resulted in a dimensionless peak wind velocity of 0.62 and 0.82 for railway line-1 at wind angles of 90 degrees and 75 degrees, respectively, and the corresponding values were 0.81 and 0.97 for railway line-2. The flow structure analysis revealed the reason for the mismatched height in the transition region, and the right-angle structures of the windbreaks resulted in ineffective protection and sudden changes in the wind speed and direction. Two mitigation measures - oblique structure (OS) and circular curve structure (CCS) transition walls - were developed to reduce the peak wind speed. The OS provided superior protection. The peak value of dimensionless wind velocity was all less than 0.2 for OS and CCS. Originality/valueThe flow field deterioration mechanism induced by the inappropriate form of a windbreak transition at different wind angles was examined, and effective mitigation and improvement measures were proposed and compared with the original transition.

Automated summary

This study aims to investigate the variations in flow fields induced by windbreak transition regions and propose mitigation measures to improve windproof ability. Improved simulation methods were used to simulate the impact on flow structures under different wind angles, and the accuracy of the results was validated with wind tunnel tests. The original windbreak transition region resulted in high peak wind velocities, but mitigation measures such as oblique and circular curve structures were effective in reducing peak wind speeds.