Virtual homologation of high-speed trains in railway tunnels: A new iterative numerical approach for train-tunnel pressure signature

Large overpressures can be produced when a high-speed train enters and crosses a railway tunnel. Predicting them is important since, in critical conditions, pressure variations may be dangerous for train structures and for passengers’ health and comfort. European regulations impose pressure thresholds which trains must comply with in order to be homologated for travelling through tunnels. Currently, full-scale tests are required to demonstrate respect of these prescriptions. In this work, a procedure for calculating the pressure variations inside the tunnel based on 3 D steady CFD simulations and a 1 D compressible fluid-dynamics model is proposed, to be used both as a design tool and for virtual homologation of new rolling stock. Results of a large experimental campaign performed on the Italian high-speed line are used to set-up the proposed methodology and to validate it. Different train geometries, tunnel crossing speeds and tunnel initial air conditions are considered.