Fire is a critical regulator of biogeochemical cycles in approximately 40% of the earth's land surface. However, little is known about nutrient release from combustion residues (ash and char) from herbaceous or grassland fires of varying intensity. Much of our knowledge in this area is derived from muffle furnace temperature gradient experiments. Therefore, we used two approaches (muffle and fl...

This paper presents the design, implementation and evaluation of an instrumentation system for the stability monitoring and characterization of combustion flames. The system, incorporating optical sensing, image processing and spectral analysis techniques, is designed to monitor a range of flame characteristic parameters. The stability of the flame is assessed through statistical analysis of th...

Flame stabilization by swirl is a common feature of many combustors. While most of the swirl combustors are enclosed, there have been relatively few studies of open swirl-stabilized flames. In the current study, an open swirl-stabilized turbulent premixed flame is studied numerically. The purpose of this work is to obtain a better understanding of the flame properties by simulating the flow fie...

An experimental study of the combustion of an aerosol of coarse magnesium particles in microgravity is reported. Particles with sizes between 180–250 mm were aerosolized in a 0.5-L combustion chamber and ignited in a constant-pressure, microgravity environment. Two flame images were produced simultaneously using interference filters separating adjacent MgO and black body radiation bands at 500 ...

Ultra-lean, hydrogen-air mixtures are found to support another kind of laminar flame that is steady and stable beside flat flames and flame balls. Direct numerical simulations are performed of flames that develop into steadily and stably propagating cells. These cells were the original meaning of the word “flamelet” when they were observed in lean flammability studies conducted early in the dev...

The small radiant heaters that burn hydrocarbon fuels propane, butane, methane/natural gas and liquid hydrocarbon fuels are used widely because of their simple design, their portability, and the ready availability of fuels. The open flame heater presents obvious disadvantages as follows. An upset heater is a grave fire risk where the surroundings are flammable and this restricts usage in, for e...

Since a large number of physical variables are involved in the combustion process occurring in complex swirl stabilized combustors, simple systems (burner stabilized laminar flat flames) were initially studied (see chapters 5 and 6). Having understood the dynamics of laminar flat flames and developed methodologies to build reduced order flame dynamic models, the technique developed to measure t...

Turbulent-flame speeds in methane–air mixtures were measured in a Taylor–Couette apparatus with counter-rotating cylinders, used to generate turbulence that is nearly homogeneous and isotropic over many integral length and time scales. While laminar-flame propagation is found to be influenced by the Darrieus– Landau instability and heat loss to the walls of the apparatus, turbulent-flame propag...

The effect of inlet swirl on the flow development and combustion dynamics in a lean-premixed swirl-stabilized combustor has been numerically investigated using a large-eddy-simulation (LES) technique along with a level-set flamelet library approach. Results indicate that when the inlet swirl number exceeds a critical value, a vortex-breakdown-induced central toroidal recirculation zone is estab...

• To develop a prototype optical instrumentation system capable of measuring the distributions and fluctuations of temperature and soot concentration of pulverised coal flames. • To evaluate the performance of the system on a 0.5MWth combustion test facility at Innogy plc over a range of combustion conditions. • To establish quantitative relationships between the flame temperature and soot conc...