Journal ArticleDOI
Intrinsic Flame Instabilities in Premixed and Nonpremixed Combustion
TLDR
In this article, the role of differential and preferential diffusion, thermal expansion, and heat losses in intrinsic combustion instabilities in both premixed and non-premixed systems is discussed.Abstract:
The focus of this article is on intrinsic combustion instabilities in both premixed and nonpremixed systems, identifying, in particular, the roles of differential and preferential diffusion, thermal expansion, and heat losses. For premixed flames, the hydrodynamic instability resulting from thermal expansion plays a central role and is particularly dominant in large-scale flames. It is responsible for the formation of sharp folds and creases in the flame front and for the wrinkling observed over the surface of expanding flames. In contrast, instabilities in diffusion flames, which give rise to cellular and oscillating flames, are mainly driven by diffusive-thermal effects, with thermal expansion playing a secondary role. The discussion also includes instabilities of edge-flames in unmixed reactants, which possess stability characteristics of both premixed and diffusion flames, but with a distinct mode of instability.read more
Citations
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Journal ArticleDOI
State-of-the-art in premixed combustion modeling using flamelet generated manifolds
van Ja Jeroen Oijen,A Andrea Donini,Rjm Rob Bastiaans,ten Jhm Jan Thije Boonkkamp,de Lph Philip Goey +4 more
TL;DR: In this paper, the generalized flamelet model is used for the modeling of premixed and partially-premixed flames, and the results compare well with numerical results for flames with thin reaction layers, but described by multiple-species transport and chemistry.
Journal ArticleDOI
Combustion at a crossroads: Status and prospects
TL;DR: In this paper, the state of combustion is evaluated and its prospect as a vibrant branch of science is assessed, and it is concluded that combustion has much to offer in terms of technological relevance and intellectual challenge, and as such will remain as a robust scientific discipline for years to come.
Journal ArticleDOI
Laminar burning characteristics of 2-methylfuran and isooctane blend fuels
TL;DR: In this article, high-speed schlieren photography is used to investigate the laminar burning characteristics of gaseous 2-Methylfuran (MF)-isooctane at varying temperatures and equivalence ratios.
Journal ArticleDOI
Freely-propagating flames in aluminum dust clouds
TL;DR: In this article, the free propagation of isobaric flames through aluminum dust clouds is investigated in an extensive series of experiments using two facilities with different scales in small-scale laboratory experiments, and in large-scale tests, flames propagate vertically through unconfined aluminum dust cloud with a vertical scale of about 4m.
Journal ArticleDOI
Intrinsic Thermoacoustic Instability of Premixed Flames
TL;DR: In this paper, a causal representation of the flow-flame-acoustic interactions reveals a flame-intrinsic feedback mechanism, which can be described as follows: an upstream velocity disturbance induces a modulation of the heat release rate, which in turn generates an acoustic wave traveling in the upstream direction, where it influences the acoustic velocity and thus closes the feedback loop.
References
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Journal ArticleDOI
Nonlinear analysis of hydrodynamic instability in laminar flames—I. Derivation of basic equations
TL;DR: In this paper, an asymptotic nonlinear integrodifferential equation for spontaneous instability of the plane front of a laminar flame is derived, and it is shown that in all cases spontaneous instability implies an increase in its propagation velocity.
Journal ArticleDOI
Flames as gasdynamic discontinuities
TL;DR: In this article, an equation for the propagation of the discontinuity surface for arbitrary flame shapes in general fluid flows is derived, where the structure of the flame is considered to consist of a boundary layer in which the chemical reactions occur, located inside another boundary layer, in which transport processes dominate.
Journal ArticleDOI
Instabilities, Pattern Formation, and Turbulence in Flames
TL;DR: In this paper, it was shown that the rate of a chemical reaction (W) in a gaseous mixture is an increasing function of tempera- ture; usually W ex.l.p(E / RT), where E is a constant specific to the reaction and RT is the universal gas constant.
Journal ArticleDOI
The measurement of laminar burning velocities and Markstein numbers for iso-octane-air and iso-octane-n-heptane-air mixtures at elevated temperatures and pressures in an explosion bomb
TL;DR: In this article, the effects of the initial mixture temperature and pressure on these parameters also have been examined and data have been obtained for iso-octane-air mixtures at initial temperatures between 358 K and 450 K, at pressures between 1 and 10 bar, and equivalence ratios, φ, of 0.8 and 1.0.
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