摘要:

Flame front geometry and flame stretch during interactions of premixed flames with vortices at various configurations are computationally investigated using a kinematical relationship between vortex-induced velocity and flame propagation velocity, in conjunction with Lagrangian coordinates to represent the flame front. The maximum flame stretch that can occur during an interaction with a single vortex is found to be very close to Uθ/rm+ SL/2rm, while the mean flame stretch has a maximum that asymptotes to 18-23% of this value for vortex radii between 1.25 and 5.0 mm as UθSLis increased to 2. For flames interacting with a counter-rotating vortex pair, the flame stretch near the flow symmetry axis increases when the spacing between the vortices increase to align the velocity vectors with the flame front; while the flame stretch away from this region is relatively independent of the action of the opposite vortex and is determined primarily by the vortex velocity and length scale similar to the single vortex case. For flame contours caused by vortex arrays, the flame curvature scales more strongly with vortex size than vortex velocity; and the mean flame curvatures for both vortex arrays and a single vortex are bounded between 1/dmand 1/(2dm) except in an instance where the vortex produces negligible wrinkles on the flame front. The effect of decreasing the tangential spacing in the vortex array is to increase the coupling of actions of adjacent vortices which leads to an increase in flame area and a positive shift in the flame curvature pdf; while variations of normal vortex spacing have less effect on the flame front geometry. The maximum flame stretch for flames interacting with vortex arrays is found to be close to the value caused by a single vortex, whereas the mean flame stretch and higher statistical moments are significantly different due to the additional strains caused by the coupling of actions of adjacent vortices.

ISSN:0010-2202    

DOI:10.1080/00102209308907611

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A solution of the stationary cylindrical flame in both source and sink configurations is obtained analytically using simplified reaction rate and diffusion models. The solution is used to investigate the effects of curvature in the absence of stretch and identify the ranges where ducting and source/sink effects are dominant. We also investigate the concept of a minimum radius of curvature by introducing non-local effects on the flame.

ISSN:0010-2202    

DOI:10.1080/00102209308907612

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Controlling SO2emissions in an unpulverized-coal-fired Rijke-type pulsating combustor is performed by burning with the limestone or dolomite additive. A series of parametric study are conducted to better understand the performance and mechanisms of the SO2capturing process in the pulsating combustor. Results show that the SO2reduction efficiency is dependent on the mass ratio of additive to the sulfur in fuel, but independent on the type of calcium carbonate additives. Particle size of additives has significant effect on SO2reduction efficiency particularly in small size subrange. The SO2capturing process is proved to be diffusion-controlling in the present pulsating combustor. It is found that the presence of CO in the combustor suppresses the SO2reduction capability.

ISSN:0010-2202    

DOI:10.1080/00102209308907613

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The present study has been performed to explore the local reaction zone configuration of high intensity turbulent premixed flames in detail by using a micro-electrostatic probe of two identical sensors. The local reaction zone configuration is shown to be determined by analyzing the ion current fluctuations.

ISSN:0010-2202    

DOI:10.1080/00102209308907614

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A simple thermodynamic model of combustion in Otto cycle engines has been published and shown to exhibit chaotic cycle to cycle variations in certain regimes. However, these chaotic regimes are far from any physical limit. When the model is modified to predict observables within their physical ranges, the chaotic behaviour disappears. It is not possible from these results to claim that the fuel thermo-chemistry alone can induce chaotic behaviour. By elimination, this would support the view that cycle-to-cycle variations are caused by the effects of turbulence on fluid flow and combustion in engines, and not by chaotic phenomena arising from the non-linearity of fuel thermo-chemistry.

ISSN:0010-2202    

DOI:10.1080/00102209308907615

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor