Numerous investigations have been conducted to determine the effect of fuel composition and molecular structure on particulate emissions using exhaust gas analysis, but relatively few measurements have been obtained in-cylinder or under conditions where fuel effects can be isolated from other variables. In this work, dimethoxymethane was used as the base fuel to produce a non-sooting flame in a constant volume combustion vessel at 1000 K, and a density of 16.6 kg/m3. A second fuel was then added incrementally to determine an incipient soot limit. Line-of-sight extinction measurements were used as the primary diagnostic tool to determine if a correlation exists between soot and fuel properties. These data indicate that fuels with carbon double bonds are more prone to soot than the single bonded fuels. Each of the four pure additives tested began to soot at a structure-weighted available oxygen-to-carbon ratio near one. The commonly used two-color method for measuring temperature and soot concentration (KL) was used as a secondary method. A method for calibrating and analyzing the uncertainty of the temperature and KL measurements with a single color RGB digital camera was demonstrated. Images of reacting jets of different soot concentrations are shown along with an uncertainty analysis. The resulting temperature and KL maps show uneven distributions for flames of various fuels. Analysis shows that the temperature and KL values of heavily sooting fuels are primarily a result of conditions (temperature and soot concentration) within a 1—2 mm region on the surface of the jet, where a turbulent diffusion flame is present. As soot concentration decreases, the region of influence affecting the result thickens, allowing more influence from within the jet, lowering the measured temperature. Therefore, a low-sooting jet appears to have a lower temperature than a high-sooting jet. Extinction and two-color soot measurement results were compared. The two-color KL values were seen to level off at around 0.5, but continue to increase monotonically as soot increased. The broad band method is therefore not good for absolute soot measurements. Natural luminosity measurements were sensitive to the first appearance of soot, but were non-linear.

For roughly the past 200 years land-managers have used the practice of “muirburning” to manipulate the structure of heather (Calluna vulgaris) to create a patchwork of habitat structures able to provide forage and nesting sites for red grouse (Lagopus lagopus scoticus) as well as grazing for sheep (Ovis aries) and red deer (Cervus elaphus). This thesis investigates both the behaviour and impact of management fires in recognition of the need to develop multi-aim land management practices that ensure both continued productivity and protection of biodiversity in the face of climatic and environmental change. Fuel structure and loading are crucial controlling factors on both fire behaviour and impact governing both rate of spread and heat release to the ground surface. A visual obstruction method is developed that estimates total and fine fuel loading as well as the structure of the heather canopy. In order to adequately understand fire impact a dimensional analysis approach is taken to estimating the mass of burnt heather stems. Experiments at a number of spatial and temporal scales relate variation in heather fuel moisture content to stand structure and variation in weather conditions. Monitoring shows moisture contents to be relatively stable temporally, but spatially variable. Periods of extreme low moisture contents in early spring are associated with frozen ground, winter cuticle damage and physiological drought. Such conditions may have contributed to the large number of wildfires in 2003. A replicated plot design was used to investigate the effect of weather conditions and fuel loading on fire behaviour. An empirical approach is taken to fire behaviour modelling with equations describing rate of spread and fireline intensity being developed on the basis of fuel structure descriptors and windspeed. The theoretical negative correlation between fuel bed density and rate of spread is demonstrated to hold true for heather stands, while the impact of heterogeneity in fuel bed structure is also investigated. Redundancy Analysis is used to investigate the influence of multiple predictors on a number of aspects of fire behaviour including: rate of spread, fireline intensity, flame length and ground surface heating. Data from this and previous studies are used to ground-truth a number of fire behaviour prediction systems including BehavePlus and the Canadian Fire Behaviour Prediction System. Finally linkages between fire behaviour, fire severity and heather regeneration are investigated. A number of proxy measures of ‘Immediate Severity’ are tested and used to examine the influence of fires on plant regeneration. The post-fire development of stands is shown to relate primarily to stand age and structure before burning, and to post-fire substrates rather than variation in fire behaviour and severity.

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