Some stochastic properties of fire plumes

Reaction to fire tests are the main criteria used by legislators of fire regulations to determine the suitability of different materials for use in building construction. These do not always give reliable results, particularly when applied to new man‐made materials. Part of the explanation for this is the lack of detailed understanding of the heat and mass transfer processes occurring in fire. This is in part due to a lack of measurements of the fluctuating property field in the source plume. In this paper measurements of the probability density functions, spectra and mean square fluctuations of temperature together with the probability of combustion are reported for a stimulated fire plume. The results are consistent with the model of a fire comprising a series of narrow flame fronts oscillating at the flame flicker frequency (which for this system is 3 Hz). The effects of thermal inertia in thermocouples on the determination of mean and fluctuating gas temperature have been examined using the treatment of Ballantyne, Boon and Moss. The high‐frequency limitations of thermocouple and electrostatic probes have been discussed in the context of trubulent filed measurements in fires.