Safety to Crosswind of Railway Vehicles Passing by a Windbreak Gap: Numerical-experimental Methodology

One of the main countermeasures to the problem of crosswind in railway vehicles is the introduction of windbreaks in the windiest points of a railway line. However, in some cases due to the morphology of the terrain or because operational reasons, gaps can be found in the stretch of windbreaks with a consequently reduction of efficiency. The goal of this work is to develop a methodology for the evaluation of the effects on the safety to crosswind of high-speed trains running in a track where a gap is present in barriers. An innovative numerical-experimental procedure has been developed based on experimental full-scale tests, wind tunnel tests, CFD with moving mesh and multi-body simulations. An “amplification function”, defined as a non-dimensional function which represents the amplification effect due to the gap was evaluated for different scenarios. This amplification function is then combined with the force, obtained with the stochastic methodology for the evaluation of the aerodynamic force in presence of turbulent wind. The new forces accounting for the gap presence in the windbreak barriers, are the input of the multi-body model used for the evaluation of the train stability by computing the CWC, it means, the critical wind speeds that leads the vehicle to overcome the overturning safety limit threshold. The results for a high-speed train and porous windbreaks with gap of different dimensions have shown a reduction in CWC values.