Computation of the 3D turbulent Flow surrounding a high-speed train mock-up including the inter-car gap and the bogie, and comparisons with LDV data

This paper presents an important part of the validation process of the French National Railway CFD methodology to compute complex 3D external airflows around trains. A reduced-scale test was first conducted in an open wind tunnel with a 1/7 scale TGV train set mock-up to produce a Laser Doppler Database related to the viscous turbulent air flow. Two components of the instantaneous velocity vector were measured by LDV, along the train mock-up, within the boundary layer, under the train, upstream and downstream the inter-car bogie. Then a complete Navier-Stokes calculation was run, based on this test, and the numerical results were compared with the experimental data. Comparisons were based on the mean velocity and turbulent fields. Quite good agreements were obtained and predictive actions can be today engaged to solve, by the mean of the CFD, technical problems in the field of stationary flows around trains.