摘要:

The occurrence of detonation velocities in excess of the equilibrium C-J predictions in the Hydrogen-Chlorine mixture due to the chemical kinetics of the H2-Cl2system is investigated experimentally and numerically. The new results conclusively determine the pathological nature of the H2-Cl2system and confirm the hypothesis of Zel'dovich and Ratner (1941) and Guenoche et al. (1981) regarding the kinetics of this mixture.

ISSN:0010-2202    

DOI:10.1080/00102200008947324

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102200008947325

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This article summarizes possible mechanisms of turbulence generation at the premixed flume front elucidated through recent studies. The aspects of flame front turbulence generated under various conditions are presented and the issues on current understanding of the mechanisms of turbulence generation are pointed out. Some mechanisms assumed to cause the flame induced turbulence are shown to be not effective for increasing the turbulence intensity at the flame front. Also, the scale of turbulence appearing on the flame front is discussed. Consideration of the lifetimes of vortices and of the process of flame front deformation is shown to be important for understanding the structure of turbulent premixed flames. The lifetimes of vortices smaller than the scale of the flame front disturbance caused by its instability are too short for these structures to be effective in enhancing the flame front turbulence. Thus, the minimum scale of the turbulence observable at the flame front would be comparable to that of the disturbance caused by flame front instability, and distributed reaction zones hardly appear even in high-intensity turbulent flames.

ISSN:0010-2202    

DOI:10.1080/00102200008947326

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The flame propagation and structure of a stoichiometric methane-air flame in a closed vessel is investigated. For the parameter range examined a tulip flame is formed. A qualitative agreement with experiments is obtained for different length to width ratios of the vessel. The results indicate an enhanced tulip effect with increasing vessel length.

ISSN:0010-2202    

DOI:10.1080/00102200008947327

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Flame propagation in a tube of constant cross section with ignition at the closed end and propagation toward the open end was studied experimentally, in propane-air, ethylene-air and acetylene-air mixtures. The flame trajectory displays an oscillatory behaviour which can be correlated to pressure records. The overall phenomenon is highly dependent on the mixture composition and the tube length.

ISSN:0010-2202    

DOI:10.1080/00102200008947328

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The dynamic process of the interaction between a jet flame and a lateral wall is experimentally studied. The evolution of the outer buoyant vortices, which are involved in the jet flame bulge and flame tip-cutting phenomena, is found to play the central role in the flame-wall interaction process for low speed jet flames. The flame response as the lateral wall approaches from infinity can be categorized into five characteristic stages based on the ratio of the flame bulge size on both sides. As the wall approaches, the flame is observed to first increase in the size of the flame bulge on the wall side. Then, flame is wiggling with off-set flame bulges on both sides. The flame is then seen to incline and attach to the wall, and finally flame on the wall side is complete quenched as the separation distance is further reduced. These variations in flame structure are closely related to the retarded evolution of the buoyant vortices due to the wall and are scaled and explained based on similarity as well as the induced strain rate due to the variation of the outer vortices.

ISSN:0010-2202    

DOI:10.1080/00102200008947329

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

To further current knowledge of how strain effects the structure of impinging flames and how these effects play a role in the surface modification of polymer films, two premixed impinging flames are modeled using the SPIN application of the CHEMK1N software: in Case 1, a methane - air flame, and in Case 2, a methane - air flame with 4.5% nitrous oxide additive. In Case 1, the quenching activates six reactions that consume O, H, and OH, while H2O2and HO2are produced. In Case 2, the quenching and N2O additive further consume the oxidizing species, while HNO, N2O, NO, and NO2are produced in significant quantities through activation of six additional reactions. It is shown that the strain applied to the flame by impingement on the cool stagnation surface leads to secondary reactions in the quench zone that are directly responsible for the modification of the polymer film surface.

ISSN:0010-2202    

DOI:10.1080/00102200008947330

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The problem of homogeneous solid propellant combustion instability is studied with a one-dimensional flame model, including the effects of gas-phase thermal inertia and nonlinearily. Computational results presented in this paper show nonlinear instabilities inherent in the equations, due to which periodic burning is found even under steady ambient conditions such as pressure. The stability boundary is obtained in terms of Denison-Baum parameters. It is found that inclusion of gas-phase thermal inertia stabilizes the combustion. Also, the effect of a distributed heat release in the gas phase, compared to the flame sheet model, is to destabilize the burning.

ISSN:0010-2202    

DOI:10.1080/00102200008947331

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The paper deals with the problem of mitigation of the explosion initiated in a vessel and vented through a duct.

ISSN:0010-2202    

DOI:10.1080/00102200008947332

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The objective of this work was to apply visualization methods to the experimental study of cornstarch dust-air mixture combustion in a closed vessel volume under microgravity conditions. A dispersion system with a small scale of turbulence was used in the experiments. A gas igniter initiated combustion of the dust-air mixture in the central or lop pan of the vessel. Flame propagation through the quiescent mixture was recorded by a high-speed video camera. Experiments showed a very irregular flame front and irregular distribution of the regions with local reactions of re-burning behind the flame front, at a later stage of combustion. Heat transfer from the hot combustion products to the walls is shown to have an important role in the combustion development. The maximum pressure and maximum rate of pressure rise were higher for flame propagation from the vessel center than for flame developed from the top part of the vessel. The reason for smaller increase of the rate of pressure rise, for the flame developed from the top of the vessel, in comparison with that developed from the vessel center, was much faster increase of the contact surface of the combustion gases with the vessel walls. It was found that in dust flames only small part of heat was released at the flame front, the remaining part being released far behind it.

ISSN:0010-2202    

DOI:10.1080/00102200008947333

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor