Development of Ventilation System for Nonsmokers Used in Hall without Partition

Abstract

We often perceive odors of smoking at seats for non-smokers of cafés and restaurants. A new ventilation system was developed by using the knowledge that neither flow separation nor backward flow could occur in case of increasing velocity distribution near walls. Air was supplied with uniform velocity distribution from the whole surface of one side wall and exhausted from the slits set at upper and lower positions of the opposite side wall. The effects were examined experimentally and by means of CFD, and it was confirmed that neither separation nor backward flow occurred even when furniture was set. Furthermore, it was examined experimentally and was confirmed that supplying unsteady flow was effective to prevent the growth of wakes behind obstacles and to decrease the amount of remaining smoke there, when Strouhal number based on the frequency of unsteady flow and the characteristic length of obstacle was about 0.2. These findings seemed useful to ventilate passenger cabins of airplanes or trains, where many seats were arranged densely.