Paper detail

Contaminant transport by human passage through an air curtain separating two sections of a corridor: Part I -- uniform ambient temperature

Air curtains are commonly used as separation barriers to reduce exchange flows through an open-door of a building.Here, we investigated the effectiveness of an air curtain to prevent the transport of contaminants by a person walking along a corridor from a dirty zone into a clean zone. We conducted small-scale waterbath experiments with freshwater, brine and sugar solutions, with the brine as a passive tracer for the contaminant in the wake of person. A cylinder representing human walking was pulled between two fixed points in the channel across the air curtain. We observed that the air curtain can prevent up to 40% of the contaminant transport due to the wake of a moving person.We proposed a new way to evaluate the performance of an air curtain in terms of the deflection modulus and the effectiveness defined for this iso-density situation, similar to quantities typically used for the case where the fluid densities in the two zones are different. We observed that the air curtain has an optimal operating condition to achieve a maximum effectiveness. Dye visualisations and time-resolved particle image velocimetry of the air curtain and the cylinder wake were used to examine the re-establishment process of the planar jet after its disruption by the cylinder and we observed that some part of the wake is separated by the re-establishing curtain. We observed that the exchange flux peaks after the cylinder passes the air curtain and reduces to a typical value after the re-establishment of the curtain.