This thesis examines the theoretical basis for and the experimentation supporting the predictive smoke models currently being used in fire engineering design that is being used, in nationally and internationally accepted guidance documents, to support the increasing use of performance-based building codes/regulations throughout the world. In carrying out this critical examination numerous anomalies are identified between different researcher's results, when considering the same fire environment, and areas where the models put forward in accepted guidance documents have little or no empirical support. This variance between models is demonstrated by the parametric variation of critical data input parameters. To carry out the parametric variation of these input parameters an Excel© calculation system was devised in order to present the information in both graphical and tabular form. The results from the Excel° `experimentation' indicates that the most recent research has resulted in models that predict a lower level of mass smoke flow than the earlier research. It may be suggested that the more recent research, following on and adding to the results of previous researchers produces models that can be used with a greater level of confidence but there is no robust evidence to support this. Currently there is a move towards the use of Computational Fluid Dynamic modelling of fire. However, given the lack of validation of these types of models in the area of smoke movement and the computer time and power required to run these models, there is still a place in fire engineering design for the zone model. It is concluded in this research that, as an increasing number of countries adopt performance building and fire codes/regulations and we lack predictive mass smoke flow models in which regulators, fire engineers and society can have confidence in, the research supporting zone modelling of fire should be extended. It should be carried out in a robust and transparent way in order to either produce models that are substantially more acceptable than those currently being used or to provide more acceptability of current models and their limitations.

No description available.

No description available.

No description available.

No description available.

The steady state tube furnace (Purser furnace, BS 7990 and ISO TS 19700) has been used in conjunction with FTIR gas analysis to investigate the toxic product yields of fire effluents. The repeatability and interlaboratory reproducibility of the apparatus is shown to be satisfactory, based on results from 6 operators at 4 laboratories. The set-up and calibration of FTIR for gases and volatiles is described, together with a discussion on reliability and interpretation of spectra. A novel recirculation system for calibration of volatile components (including organoirritants) has been validated by quantification in triplicate. Seven materials (LDPE, Nylon 6.6, Polystyrene, PVC, Medium density fibreboard with and without flame retardant and glass reinforced polyester) were investigated under different fire conditions, and the results presented in terms of toxic product yields and predicted fire gas toxicity as a function of equivalence ratio. This showed that in the case of PVC and nylon 6.6 the most toxicologically significant species were HCl and HCN respectively, in other materials, such as LDPE and polystyrene, CO was the major toxicant, and for the polyester, very high yields of CO were observed. Data from the Purser furnace and the NF X 70-100 toxicity test are compared for the seven materials, showing generally good agreement for all products except hydrocarbons. The clearer definition of fire condition from the Purser furnace allows better estimation of the fire condition of the NF X test. The yields of CO and hydrocarbons show good agreement with predictions based on data from the fire propagation apparatus (ASTM E2058), both methods using equivalence ratio to define the fire condition. Similar comparisons have been made with large scale test data from the ISO 9705 room again showing good agreement, and highlighting the ability of the tube furnace to identify the fire condition occurring in the large scale test.

This study describes the simulation and experimental investigation of a heptane pool fire, burning within a small compartment, in which interaction between a number of key physical processes is amplified. In particular, the configuration emphasises the coupling of buoyancy induced ventilation, smoke production and radiation heat transfer to the liquid fuel surface, from the luminous flame zone, from the smoke filled ceiling layer and from the confining walls. This study contrasts with those customarily performed for the purpose of model validation in compartment fires, which employ gas burners and so simplify much of the interaction. Initial experiments were carried out using a 0.23m diameter circular pan burning fixed amounts of heptane. Subsequently, a constant supply was used with a smaller circu- lar pan of 0.17m in diameter, in order to introduce experimental longevity under safe, controllable conditions whilst establishing a quasi steady-state system. Issues of non- stationarity in relation to heat-feedback to the fuel surface - an important pool fire mech- anism - are discussed. In addition to probe measurements of velocity and thermocouple temperature, the smoke yield was determined using a light extinction technique employing a 670nm wavelength diode laser and photo-diode detector, housed within a novel fully-traversible water- cooled probe. Data from these experiments illustrate the importance of accounting for room ventilation in terms of overall production of smoke and sound a cautionary note to the labelling of soot by a convenient marker such as temperature. Numerical simulation of the compartment fire is performed using the field model SOFIE, incorporating a simple evaporation model, which relates the mass-loss-rate of fuel to the net heat flux to the fuel surface and heat of gasification. This relationship assumes that heat losses to the pan, re-radiation by the fuel surface and other enthalpy loss terms, are small. Simulations of compartment fire scenarios using this model to calculate the rate of heat release are reported. Further comparisons are made between the industry stan- dard 'Eddy-Breakup' combustion model and the 'Laminar Flamelet' model. In general both the eddy-breakup model and laminar flamelet model tend to underpredict the yields of CO, whilst the eddy-breakup model over-predicts temperature and thus soot. The laminar flamelet approach shows more promise and shows particularly good agreement with the experimental measurements reported here under well ventilated conditions. SORE, the predictive tool employed in this research, has proved invaluable in discern- ing the reason for apparent ambiguities in the experimental measurements of soot con- centration. The results suggest that an alternative simplified zone model approach would overpredict visibility in smoke in terms of concentration, but underpredict in terms of layer depth, due to its inability to capture the important shape of the hot upper layer, which varies significantly from the homogenous, laterally uniform distribution which is assumed. The incorporation of a simple evaporation model which relies on accu- rate prediction of heat transfer in ultimately determining the heat release rate has been shown to be in very good agreement with the experiments. Despite the irregularity in predicted distribution of mass loss rate across the fuel surface - caused mainly due to the 'ray effect' of the radiation model - the main trend of lower heat transfer at the centre of the burner is demonstrated, in agreement with the experiments performed. This phe- nomenon is captured despite the lack of description of fuel vapour radiation blockage above the fuel surface, suggesting that this process may be disregarded. The heat flux distribution which is found here is in contrast to research conducted by other workers for similar sized pans in an open environment, which show a higher measured heat transfer at the centre of the burner. It has been shown that significant improvements could be made in experimental design of compartment fire experiments if CFD prediction is considered for the determination of suitable measurement locations in regions with lower local spatial variations.

The dynamics of the intrinsically unstable premixed flames propagating in channels is studied by means of numerical modelling in this work. Critical conditions of extinction and the influence of the thermal-diffusive effect on the dynamics of flame propagating in planar channels with cold sidewalls under gravity is investigated. For the horizontally propagating flames, the appearance of inversion influences the effect of thermal-diffusion on the asymmetry of flame fronts. For upwards propagating flames, the convex shape of the flame imposed by the mode of ignition combined with buoyancy can suppress the thermal-diffusive effects; in contrast, the buoyancy alone cannot damp the thermal diffusive effects even for quite large Froud numbers in regard to the appearance of inversion. The variation of Lewis number has no essential effect on the planar flame shape formation when flame propagates downward. Lowering Lewis number can significantly decrease the critical conditions of extinction. However, if Lewis number is smaller than some limit, its further effect on the critical extinction conditions is unsignificant. In the two-step consecutive reaction, the effects of the ratio of Damkohler numbers, heat release rates, activation energy and Lewis number on the separation and fragmentation of flames are considered. The inversion is more pronounced in combustion with separated flame fronts than for single-step reactions. However, the inversion is obvious only when the two flame fronts are close enough to each other. Thus, the details of combusiiition chemistry may have a strong effect on the stability of the flame front. The thermal diffusive effect of the first flame is, in certain way, dominant and has influence on the second flame. The presence of the first reaction suppresses the thermal-diffusive effect of the second reaction in regard to the appearance of inversion. The propagation of flames at a variety of Reynolds number ranging from 70 to 1000 are explored. For longer channels or a flat initial flame front, the inversion of the flame is apparent for Reynolds number higher than 200. For large &, the computational grids should be very fine because of the small thickness of preheat zone. The Generalized Curvilinear Coordinate Gridding method is introduced and an elliptic grid generator based on the variational approach is employed to construct the solution-adaptive grids. However, we found out that the global structure of the algorithm required by the adaptive grid approach might be not as efficient as simplified non-adaptive grids for prospective use of massively parallel computers.