Topic
Laminar flame speed
About: Laminar flame speed is a research topic. Over the lifetime, 5824 publications have been published within this topic receiving 160617 citations.
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TL;DR: In this article, the laminar flame speeds of methane + air and propane + air mixtures, with and without the addition of stoichiometrically small amounts of hydrogen, have been determined by first measuring the flame speeds with stretch and then linearly extrapolating these values to zero stretch.
508 citations
TL;DR: In this paper, an experimental investigation of acoustically forced lean premixed turbulent bluff-body-stabilised flames in an enclosure short enough so that no coupling of the combustor downstream acoustics occurred for the frequencies studied here, which allows an unambiguous examination of the flame response to inlet velocity fluctuations.
503 citations
TL;DR: In this paper, convective effects of the flow modulations propagating upstream of a premixed laminar flame are considered and a unified model is derived analytically, based on a linearization of the G-equation for an inclined flame.
446 citations
TL;DR: In this article, various factors affecting the determination of laminar flames speeds from outwardly propagating spherical flames in a constant-pressure combustion chamber were considered, with emphasis on the nonlinear variation of the stretched flame speed to the flame stretch rate, and the associated need to nonlinearly extrapolate the stretched flames speed to yield an accurate determination of the Laminar flame speed and Markstein length.
445 citations
01 Jan 1998
TL;DR: In this paper, a new methodology is proposed for direct experimental determination of laminar flame speeds, which includes the use of the stagnation flow configuration and large separation distances betwenn the nozzle and the stagnation plane, which allow for the establishment of Bunsen-type flames as the flow rate is reduced.
Abstract: The stability of premixed flames at ultralow strain rates was assessed experimentally and numerically in the stagnation flow configuration. Results indicate that there are inherent limitations in establishing weakly strained planar flames, and that the accuracy of the laminar flame speeds obtained through linear extrapolations can, thus, be compromised. In view of these limitations, a new methodology is proposed for the direct experimental determination of laminar flame speeds. It includes the use of the stagnation flow configuration and large separation distances betwenn the nozzle and the stagnation plane, which allow for the establishment of Bunsen-type flames as the flow rate is reduced. The flow velocities are measured by using laser Doppler velocimetry. The proposed technique is based on the principle that whereas the planar, strained flames are positively stretched, the Bunsen flames are negatively stretched. Thus, by achieving a smooth, quasi-steady transition between planar and Bunsen flames, the flames pass through a near-zero strain-rate state. Real-time LDV measurements were obtained at numerous fixed spatial locations in the region within which transition occurs. The minimum velocity obtained in these measurements corresponds to the flame speed at the limit of near-zero stretch and is proposed as a representative value of the true laminar flame speed, SHo. Laminar flame speeds were obtained for atmospheric CH4/air, C2H6/air, and C3H8/air mixtures and for a wide range of equivalence ratios. The new Sno values were found to be systematically lower than the values that have been determined by using the traditional stagnation flow technique and linear extrapolations to zero strain rate.
422 citations