Diffusion-flame flickering as a hydrodynamic global mode
D. Moreno-Boza,Wilfried Coenen,Alejandro Sevilla,Jaime Carpio,Antonio L. Sánchez,Amable Liñán +5 more
TLDR
In this paper, the authors employed a linear global stability analysis to investigate buoyancy-induced flickering of axisymmetric laminar jet diffusion flames as a hydrodynamic global mode.Abstract:
The present study employs a linear global stability analysis to investigate buoyancy-induced flickering of axisymmetric laminar jet diffusion flames as a hydrodynamic global mode. The instability-driving interactions of the buoyancy force with the density differences induced by the chemical heat release are described in the infinitely fast reaction limit for unity Lewis numbers of the reactants. The analysis determines the critical conditions at the onset of the linear global instability as well as the Strouhal number of the associated oscillations in terms of the governing parameters of the problem. Marginal instability boundaries are delineated in the Froude-number/Reynolds-number plane for different fuel-jet dilutions. The results of the global stability analysis are compared with direct numerical simulations of time-dependent axisymmetric jet flames and also with results of a local spatio-temporal stability analysis.read more
Citations
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Global instability of low-density jets
TL;DR: In this article, the global stability of axisymmetric low-density jets is investigated in the low Mach number approximation, and the linear modal dynamics is found to be characterised by two features: a stable arc branch of eigenmodes and an isolated eigenmode.
Journal ArticleDOI
Observed dependence of characteristics of liquid-pool fires on swirl magnitude
TL;DR: One dozen vertically oriented thin rectangular vanes, 62 cm tall and 15.2 cm wide, were placed 27 cm from the center of heptane and ethanol pool fires in continuously fed, floor-flush pans.
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On the critical conditions for pool-fire puffing
TL;DR: In this article, a global linear stability analysis that accounts for the axisymmetry of the prevailing instability mode is developed to describe the bifurcation of pool fires to a globally unstable puffing state.
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The route to chaos for plumes from a top-open cylinder heated from underneath
TL;DR: In this article, a top-open cylindrical cavity heated from the cavity bottom was simulated and analyzed for a range of Rayleigh numbers, Ra = 100 − 106, and the authors observed a succession of bifurcations from steady to chaotic plumes, with increasing Rayleigh number.
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Global instability analysis and experiments on buoyant plumes
TL;DR: In this paper, the effect of various non-dimensional parameters and inlet velocity profiles on the frequency and growth rates of the global modes of buoyant plumes is investigated and the results are used to delineate the stability boundaries for these global modes and to obtain scaling laws for the associated oscillation frequencies.
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TL;DR: In this article, the authors studied the stability of steady axisymmetric parallel flows of uniform fluid in the absence of rigid boundaries, and they focused on the stability characteristics in the limit of large Reynolds number and determined the (integral) value of n at which the growth rate is a maximum in these simpler circumstances.