[en] For over half a century, combustion researchers have studied the phenomenon of Deflagration-to-Detonation Transition (DDT). DDT phenomenon lies at the intersection of chemical kinetics, flow turbulence and compressible gas dynamics; and presents a formidable and challenging conundrum. In the nuclear industry, DDT is a known risk in accident scenarios involving unintended release and combustion of hydrogen. Through use of sophisticated measurements, experimentalists have clearly elucidated the mechanisms underlying DDT. More recently, numerical modeling has also been adopted as one of the methods for studying DDT. In this article, the multitude of effects involved in DDT have been presented from a physical standpoint. Then, numerical challenges and strategies to model DDT are described along with key validation results. Finally, the mechanistic aspects of DDT are also discussed. (author)

[en] A study was conducted at the Alberta Research Council aimed at developing equations to obtain the combustion efficiencies of solution gas flaring. Flaring of waste gas is commonly practiced by the petroleum industry in Alberta. Flaring rarely reaches complete combustion because air entrainment restricts flame sizes to less than optimum values. Equations were used to estimate flame lengths, areas and volumes of functions of flare stack exit velocity, stoichiometric mixing ratio and wind speed. Heats released were estimated from knowledge of the flame dimensions. The study showed that combustion efficiency quickly decreases as wind speed increases from 1 to 6 m/s. Combustion efficiencies were found to level off at values between 10 to 15 per cent when wind speeds were beyond 6 m/s. Propane and ethane burned more efficiently than methane or hydrogen sulphide. 23 refs., 4 tabs., 1 fig., 1 appendix

[en] In this paper the simulation of the tests THAI HD-12 and HD-22 with the flame front model (FRONT) of ASTEC using different approaches for the turbulent burning velocity is treated. Results of the simulations depend on the estimation of the turbulence intensity. Applying only one parameter set, the correlations indicate different behaviours. To show the influence of the turbulence intensity parameter, these were varied and thus, a good agreement to the experiment can be achieved with each correlation. In addition, a recommendation for the models parameter will be given for the actual used correlation according to Peters. (author)

[en] Short communication

[en] An experimental study on spherically expanding flames propagation of methane- air mixtures was conducted at constant pressure to measure unstretched laminar flame speeds, laminar burning velocity and flame stretch. The mixtures were ignited at equivalence ratios of 0.7, 0.9 and 1.0, under ambient pressure and temperature. It was found that the unstretched laminar burning velocity increased with the equivalence ratio. The flame propagation speed showed different trends at different equivalence ratio for tested mixtures.

[en] In this paper we outline our solution, of the Cauchy problem, for Majda's model of dynamic combustion, i.e. the system: (u+q_oz)_t+f(u)_χ = 0, z_t+Kφ(u)z = 0, in the class of bounded measurable functions. We define a weak entropy solution for this system, state the uniqueness theorem in this class, and outline the existence proof under the assumption that the initial data is of bounded variation. The existence is proved via the ''vanishing viscosity method''. (author). 3 refs

[en] The red emitting borate host phosphor YCaBO₄: Eu³⁺ has been prepared by a novel solution combustion technique. The synthesis is based on the exothermic reaction between the fuel (Urea) and Oxidizer (Ammonium nitrate). The photoluminescence properties of the powder samples of YCaBO₄: Eu³⁺ has been investigated under UV and VUV excitation. The phosphor shows strong absorption in UV and VUV region and exhibits intense red emission upon excited by 254 nm UV and 173 nm VUV radiation. Under UV 254 nm excitation, YCaBO₄: Eu³⁺ exhibits intense red emission around 610 nm. Under VUV excitation of 173 nm, the phosphor emits intense red emission around 610 nm and few weak emissions. These weak emissions could be suppressed by annealing the sample repeatedly at proper temperature and the borate phosphor YCaBO₄: Eu³⁺ could be a good red emitting phosphor for PDP display and mercury free lamps. (author)

[en] This patent describes a method of igniting a deuterium-tritium (DT) fuel target to obtain fuel burn. It comprises providing a fuel target that includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell, heating the fuel target uniformly to at least partially melt the frozen layer and form a liquid single phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior surface, and directing ignition energy onto the target from exteriorly of the target with the layer in the substantially uniform single or bi-phase state to ignite the DT layer

[en] The combustion of a binary mixture of methane and hydrogen has been studied using 2 different experimental setups: the spherical bomb to investigate the fundamental flame properties of this mixture with air, initially at 100 kPa, at different initial temperatures (300 - 363 K) and for a wide range of equivalence ratios (0.8 - 1.4); ENACCEF to investigate the flame acceleration phenomena in smooth tube for mixtures initially at ambient conditions and for equivalence ratios ranging between 0.57 and 0.84. A detailed kinetic mechanism has been used to derive the activation energies needed for the flame acceleration analysis. (author)

[en] The process of reactive in situ synthesis of dense ceramic matrix composites in Ti-B-C, Ti-B-N, Ti-Si-N systems is modeled. These ceramics are fabricated on the basis of compacted blends of ceramic powders, namely Ti-B₄C and/or Ti-BN. The objectives of the project are to identify and investigate the optimal thermal conditions preferable for production of fully dense ceramic matrix composites. Towards this goal heat transfer and combustion in dense and porous ceramic blends are investigated during monotonous heating at a constant rate. This process is modeled using a heat transfer-combustion model with kinetic parameters determined from the differential thermal analysis of the experimental data. The kinetic burning parameters and the model developed are further used to describe the thermal explosion synthesis in a restrained die under pressure. It is shown that heat removal from the reaction zone affects the combustion process and the final phase composition