scholarly journals Bistability of flame propagation in a model with competing exothermic reactions

2013 ◽  
Vol 469 (2158) ◽  
pp. 20130315 ◽  
Author(s):  
I. N. Towers ◽  
V. V. Gubernov ◽  
A. V. Kolobov ◽  
A. A. Polezhaev ◽  
H. S. Sidhu
Keyword(s):  
Combustion Wave ◽  
Thermal Model ◽  
Turning Point ◽  
Spatial Dimension ◽  
Premixed Combustion ◽  
Solution Branch ◽  
Crossover Temperature ◽  
Exothermic Reactions ◽  
Combustion Wave Propagation ◽  
Hysteresis Phenomena

We investigate a diffusional-thermal model with two-step competitive exothermic reactions for premixed combustion wave propagation in one spatial dimension under adiabatic conditions. A criterion based on the crossover temperature notion was used to qualitatively predict the region in the space of parameters where three travelling combustion wave solutions coexist, which are further studied via numerical means. It is demonstrated that under certain conditions the flame speed is an ‘S’-shaped function of parameters. The fast branch is either stable or is partly stable and exhibits the Andronov–Hopf (AH) bifurcation before the turning point is reached. The mid-branch is completely unstable. The slow solution branch is either unstable or partly stable and exhibits a single or a pair of AH bifurcations. The AH bifurcations are shown to be supercritical giving rise to stable pulsating waves. Bistability and hysteresis phenomena are also demonstrated.

PROPAGATION OF THE BURNING WAVE IN A PULSED DETONATION COMBUSTOR OPERATING ON MIXTURES OF HEPTANE AND JET A-1 WITH AIR AND OXYGEN AT [O2/AIR] < 1

2020 ◽  
Author(s):  
M. S. ASSAD ◽  
◽  
O. G. PENYAZKOV ◽  
I. I. CHERNUHO ◽  
K. ALHUSSAN ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Combustion Wave ◽  
Equivalence Ratio ◽  
Pressure Sensors ◽  
Jet Fuel ◽  
Propagation Time ◽  
Burning Wave ◽  
Pulsed Detonation ◽  
Combustion Wave Propagation ◽  
Fuel Jet

This work is devoted to the study of the dynamics of combustion wave propagation in oxygen-enriched mixtures of n-heptane with air and jet fuel "Jet A-1" in a small-size pulsed detonation combustor (PDC) with a diameter of 20 mm and a length less than 1 m. Experiments are carried out after the PDC reaches a stationary thermal regime when changing the equivalence ratio (ϕ = 0.73-1.89) and the oxygen-to-air ratio ([O2/air] = 0.15-0.60). The velocity of the combustion wave is determined by measuring the propagation time of the flame front between adjacent pressure sensors that form measurement segements along the PDC.

scholarly journals Combustion wave propagation and detonation initiation in the vicinity of closed-tube end walls

2011 ◽  
Vol 33 (2) ◽  
pp. 2303-2310 ◽  
Author(s):  
Jun Yageta ◽  
Satoshi Shimada ◽  
Ken Matsuoka ◽  
Jiro Kasahara ◽  
Akiko Matsuo
Keyword(s):  
Wave Propagation ◽  
Combustion Wave ◽  
Detonation Initiation ◽  
Combustion Wave Propagation ◽  
Closed Tube

Combustion Wave Propagation of a Modular Porous Burner with Annular Heat Recirculation

2019 ◽  
Vol 29 (1) ◽  
pp. 98-107 ◽  
Author(s):  
Fuqiang Song ◽  
Zhi Wen ◽  
Yuan Fang ◽  
Enyu Wang ◽  
Xunliang Liu
Keyword(s):  
Wave Propagation ◽  
Combustion Wave ◽  
Combustion Wave Propagation ◽  
Porous Burner ◽  
Heat Recirculation

The Use of Exothermic Reactions in the Synthesis and Densification of Ceramic Materials

MRS Bulletin ◽  
1987 ◽  
Vol 12 (7) ◽  
pp. 60-65 ◽  
Author(s):  
J.B. Holt
Keyword(s):  
Combustion Wave ◽  
Single Phase ◽  
General Rule ◽  
Composite Ceramic ◽  
Ceramic Materials ◽  
Careful Study ◽  
Boron Powder ◽  
Exothermic Reactions ◽  
High Temperature Reactions ◽  
Cold Pressed

This article will provide information about chemical processes which rely on the heat evolved during reaction to synthesize and, in some cases, to simultaneously density single-phase or composite ceramic materials. Although the basic concept underlying these processes is simple, the high temperature reactions are complex and require careful study with individual systems before their potential as fabrication processes can be fully realized.Many reactions between solids involving elements and/or compounds, or between solids and gases are highly exothermic. Listed in Table I is a selected group of typical chemical reactions accompanied by their calculated adiabatic temperatures. As a general rule any reaction with an adiabatic temperature ~2000°C or over can be reacted under combustion conditions. For example, suppose that a cold-pressed cylindrical compact of titanium and boron powder (Eq. 1) is ignited at the top surface with a convenient source of heat such as a laser. From the igniting surface a combustion wave rapidly self-propagates down the compact, transforming the reactants into the TiB2 product. Figure 1 shows a Ti and C powder compact where the combustion wave has progressed about halfway down the compact.

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