Impact of walking passengers on the aerosol spreading in a passenger train

Kurzfassung

In cabins and compartments of passenger trains, people are frequently moving through the aisle. Besides affecting the general quiescence and the comfort, this movement is also prone to have an influence on the aerosol particle spreading in the cabin. The latter is mainly determined by the superposition of the forced flow by the ventilation system and the thermally induced flow by the passengers and was already investigated in numerous studies. However, in dynamic situations such as the movement of passengers in the aisle, the aerosol particle spreading deviates from the steady-state case. We report on the experimental acquisition of the spreading of aerosol particles in train compartment. Therefore, a moving thermal manikin is used which represents a heat-releasing, standing passenger and which can be moved through the aisle with a peak walking velocity of 1 m/s on a traverse system. The investigations were performed in the Generic Train Compartment (GZG) of the German Aerospace Center (DLR) in Göttingen, Germany. This 6-row 24 seat compartment is fully equipped with a ventilation system and seated thermal manikins to represent the other passengers. An aerosol particle source releasing artificial saliva particles through mouth and nose in a size range of 0.3 – 2.5 µm is connected to one manikin to represent the source passenger. The local particle concentrations in the breathing zones of all other passengers are recorded simultaneously at a measurement frequency of ~1 Hz. The results highlight the impact of the movement by showing high peaks of increased local concentrations on different seats, which are up to nine times higher compared to the average concentration on this seat. Meanwhile the mean concentration in the compartment remains almost constant, while locally on some other seats the average concentration is slightly decreased. In general, the movement results in a decrease of the concentration at the highest contaminated seats near the source while increasing the concentration farther away. This effect can be explained by the additional mixing of the air in the cabin. The measurements were performed for different source locations, showing the different spreading behavior originating from aisle and window seats.