Abstract
As a fire plume becomes a driving force for diffusion of heat and combustion products in an early stage of fire, engineering correlations on fire plume are widely utilised as tools to assess fire safety of onshore buildings and plants. In the offshore environment, however, fire plume properties are considerably different from those in a compartment of onshore building because of the influence of complex ship motions. As a preliminary step, we experimentally investigate the temperature characteristic of the plume formed above the fire source with simple harmonic oscillation in unconfined space where the direction of action of gravity does not change with time. The time-averaged temperature attenuation along the centre of the fictitious rectangular fire source in vertical direction was made clear using limited experimental data. The height where the attenuation property of temperature rise changes from line fire plume to axisymmetric plume was determined based on the calculated temperature field, which was obtained by applying the conventional far-field Gaussian plume correlation for an idealised point source to the temperature field formed above a harmonically oscillating fire source. It has been clarified that an empirical correlation for this transition height can be expressed as a function of amplitude and representative length of the fictitious rectangular fire source.
