Study on multi-section, nonlinear model of flashover in a long–narrow confined space

Abstract

The particularity in building structures of long–narrow spaces makes it different from the study of flashover model from the conventional theory. In this article, based on the nonlinear dynamics theory, a multi-section model was proposed to analyze the phenomenon of flashover. In this model, long–narrow confined space was divided into several sections, and each section was further divided into two zones, as hot smoke layer and cold air layer. The continuity equation and energy equation for each control volume defined from thermal smoke layer were established. The critical radius for the onset of flashover has been determined theoretically. In this article, a comparison with experiment for a multi-section, nonlinear model of flashover is presented, and the modeling results are compared with the experimental data which were obtained through a batch of fire tests in a reduced scale, long–narrow confined space. The theoretical calculation results agree reasonably well with measured results, in which the critical temperature and fire radius of flashover can be predicted. In general, for the polypropylene cribs, the predicted results are broadly consistent with the experimental results when the fire radius is below this critical value, but for heptane and wood cribs, the predicted value is a little higher. However, the model is useful in predicting the critical fire radius and temperature for flashover. In this article, the relationship between the characteristic parameters of fuel and the critical radius of fire source has also been investigated, which is linear growth.