Empirical and experimental studies of flashover in compartment fire

Abstract

The development of enclosure fires; the essence, characteristics, hazard, prevention and control of flashover; characteristics of modem buildings and flashover in them; and distinction between backdraught and flashover were all summarized. The basic theories of flashover, major variables, research methods, means of identifying and predicting
flashover, characteristics of extrusive flames, and the application of studies of flashover in existing practice were all reviewed. Current problems of flashover were discussed and some comments on existing knowledge made.
Compartment fire experiments were described and results given. Some analytical methods used in the thesis such as error analysis, multiple linear regression analysis, dynamic response analysis and Fourier analysis were introduced. Primary data was used to study the synchronism between flashover indicators, the effects of thermal inertia of lining materials on temperature history and the development of enclosure fires when changing vent size.
A fresh regression analysis was performed to update the MQH method to include modem compartment materials with a wider span of thermal inertia. Some theoretical developments of the MQH method were then presented and tested. According to these developments and based on 101 fresh experiments, some new and improved correlations were gained. The error analyses of these correlations and relevant comparisons and discussions were given.
The heat transfer of extrusive flame was theoretically analyzed and experimentally studied. A method was proposed for calculating the radiant heat flux to external surfaces from hot gas and extrusive flame, and an experimental study was made to examine the validity of the method. Results show current practice in combating fire spread between buildings is reasonable, but that the contribution of radiant heat from extrusive flame is non-negligible for extreme circumstances. Research into the combustion of exterior wall cladding caused by extrusive flame was also described. Dynamic response and Fourier analysis of hot gas layer temperature histories has led to new proposals for early warning of flashover during a fire. As a result, some new methods of predicting the temperature history and flashover likelihood of enclosure fires were put forward.