Improving the Aerodynamic Performance of Flat-fronted Trains on Meter-gauge Railway Lines

Field measurements, wind tunnel experiments, and scale model launching experiments were conducted to improve the aerodynamic performance of flat-fronted trains on meter-gauge 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 20%.