Numerical and experimental investigations on brake particle dispersion in the flow generated by a train in an underground station

Rolling stock operation generates several metallic particles related to wheel-rail and pantograph-catenary contacts and to the wear of braking components. Despite a composition different from outdoors, particulate matter pollution in underground stations must not be ignored as no consensus exists about its health impact on commuters and workers. Assessment of commuters and workers exposure has then become of major interest. Indeed, depending on the time spent underground, their daily exposure to particles can significantly differ. As spatiotemporal distribution of particulate pollutants can influence personal exposure, in the present work, numerical simulations and wind-tunnel experiments were conducted to assess particle concentrations. The dispersion of brake particles in the wake of a typical double-deck French train within an underground station with a central platform is assessed. Results obtained at a constant train speed show a strong correlation between the wake topology and particle dispersion in relation with the dynamics of vortical structures. Higher particle number concentrations (PNC) are found between the train and the station wall compared to those depicted at the platform side.