Four plume algorithms used by three zone type building fire simulators are evaluated against experiential data of Steckler and Nakaya. Significant differences in the room flow predictions are found with even the best performing plume algorithms predicting flows well below the measured values. Differences in plume behavior is attributed to (1) the background noise (turbulence) present when the data used in formulating the algorithms was collected, and (2) the inability of the plume algorithms to easily simulate the effect of plume blowing. The behavior of the McCaffrey plume in situations were the over-fire region dominates the plume flow is discussed.
Theoretical analysis of upward flame spread based on the linearized flame height approximation is made. SQW equation on upward turbulent flame spread has been generalized to incorporate the effect of burnout, and its solution has been studied on two functional forms for local heat release rate. The solution and its analysis has revealed significance of the burnout effects on upward flame spread behavior and notable sensitivity of flame spread to material properties. All these suggest usefulness of the maximum pyrolysis front height divided by pilot flame height as a measure to evaluate fire safety and reliability of the achieved safety for wall fires.
Flame propagation has been investigated experimentally in mixtures of H2 and air in a tube with a moving water film on tube's walls. Significant differences in flame propagation with and without the moving water film are revealed. Significant intensification of combustion in these mixtures of hydrogen and air in the tube with a moving water film is demonstrated. For mixtures with relatively high burning velocities (hydrogen concentrations from 20 to 30 vol. %), the maximum explosion pressure with a moving water film is higher, than without one. Also, for mixtures with relatively low burning velocities (H2 concentration 15 vol. %) the maximum explosion pressure with a moving water film is lower than without one. This effect is due to the competition between increased heat losses by water evaporation into the combustion products and lower heat losses because of combustion intensification. The multi-peak structure of the pressure-time curve during explosion of the gaseous mixture in the tube with a moving water film is revealed. A likely reason for this is the water film experiencing superheating at its intact with the hot combustion products until the temperature exceeds the limiting homogeneous nucleation temperature and explosive evaporation of the water film follows. The possibility of a shock wave in liquid adjacent to a cavity In the combustible mixture of hydrogen and air during its combustion is found. The maximum value of the pressure in a pressure wave in the liquid is 2 - 3 times higher than the maximum explosion pressure.
A simple method for an Individual and social risk assessment for liquefied petroleum gases (LPG) storages is proposed. This method is based on a simple event tree consideration and a rather detalled account of impact factors (thermal radiation intensity. explosion pressure and impulse in a shock wave) for various accident scenarios with fires and explosions (BLEVE, vapour cloud explosion, pool fire, flash fire). The demonstration of the applicability of the method has been carried out for a typical liquefied petroleum gases storage consisting of 12 spherical vessels with volume of 600 m3 each vessel.
Mathematical model of self-heating of vegetable raw materials in the form of sphere and slice are proposed. The fact that the models fit the full-scale and laboratory test results adequately permits to use them to tackle a number of applied problems, namely, to calculate the thermal detector sensivity radius, fire hasardous rate of temperature rise, fire safe storage life of vegetable raw naterials, to access the efficiency of thermal control system.