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Sakuma Y.,Vehicle Aerodynamics Laboratory | Fukuda T.,Heat and Air Flow Analysis Laboratory | Ido Dr. A.,Vehicle Aerodynamics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

Field measurements, wind tunnel experiments, and scale model launching experiments were conducted to improve the aerodynamic performance of flat-fronted trains on metergauge railway lines. The study centered mainly on the compression pressure waves generated by trains entering single-track tunnels and aerodynamic drag acting on the vehicle. Countermeasures to reduce the amplitude of the compression waves and their gradients and the aerodynamic drag were examined. Scale model launching experiments demonstrated that tunnel entrance hoods more than 8 m long - actual size - (about one and a half times the tunnel diameter) were an effective infrastructure measure for reducing the maximum compression wave pressure gradient (dp/dt)max by approximately 70% compared to tunnels with no hood. Running tests with real trains further demonstrated that attaching aerodynamic fins to the front end of a two-car test train traveling at 120 km/h was an effective onboard measure for reducing the separated flow region, (dp/dt)max by approximately 40%, and running resistance in the open environment by approximately. Source

Saito S.,Heat and Air Flow Analysis Laboratory | Miyachi Dr. T.,Heat and Air Flow Analysis Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

Micro-pressure waves radiated from tunnel exit portals are one of major wayside environmental problems in high-speed railways, and have thus prompted many studies aimed at developing countermeasures to this phenomenon. This paper proposes a new method involving the addition of a hood to tunnel exit portals to reduce micro-pressure waves. An inside partition divides the inside of the hood in two in the vicinity of the mouth, and one of the partitioned sides is closed off. Confirmation was obtained that the hood is effective in reducing the magnitude of micro-pressure waves. Source

Miyachi T.,Heat and Air Flow Analysis Laboratory | Fukuda T.,Heat and Air Flow Analysis Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

When a high speed train enters a tunnel, a micro-pressure wave radiates out from its exit portal. The micro-pressure wave can cause wayside environmental problems. Topography around the tunnel exit portal affects the peak value of the micro-pressure wave. In this paper, model experiments using a train model launcher were performed for investigating the effects of topography around the tunnel portal on the micro-pressure wave. Four types of topographic models, infinite flat ground, excavation on one side, excavation on both sides and elevated bridge, were used to measure the spatial distribution of the peak values of the micro-pressure waves. Furthermore, a modification of a prediction model for the peak value of the micropressure wave radiation was made on the basis of the experimental results. Source

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