Fire Safety Science Digital Archive

When a fire breaks out and spreads in a building, high-temperature jet plumes ejected from windows can cause fire to spread to adjoining floors or neighboring buildings. Studies on jet plumes spouting from openings have previously been carried out, including the well-known pioneering work of Yokoi who presented theoretical and experimental findings on the temperature distributions and other properties of jet plumes1-4. His study, however, did not thoroughly cover situations where soffits were placed around openings from which plumes were ejected. His investigation covered situations where a soffit was placed at the upper end of an opening, but did not cover situations where a soffit was placed vertically distant from the upper end of an opening. More detailed studies on the effects of soffits are required in consideration of recent designs because there are various combinations of opening conditions, such as opening height and width, and soffit conditions, such as soffit length, in existing buildings. Against this backdrop, the present study aims to investigate systematically the behaviour of jet plumes by carrying out a compartment model experiment with various soffit lengths and various distances between the soffit and the upper end of the opening.