Burning velocity measurements of microgravity spherical sooting premixed flames using rainbow Schlieren deflectometry

Laminar burning velocities and Markstein lengths of premixed methane/air flames near the lean flammability limit in microgravity

“…Actually, as an expression for u L , it neglects the dq b =dt term on the right-hand of Eq. (6). Values of u L determined in this way are also plotted in Fig.…”

“…Failure to account for the stretch effects may well explain the large spread in reported burning velocity values from earlier investigations [1,2]. So far, several techniques for measuring the one-dimensional laminar burning velocity have been used, and for a wide range of temperature, pressure, and fuel rather accurate measurements have been obtained by employing flat or curved flames in stagnation flow (e.g., [3][4][5][6][7]), propagating spherical flames in combustion vessel (e.g., [8][9][10][11][12]), or flat flames stabilized on burner [13,14]. With all those measurement techniques proper care could be taken to remove the effect of flame stretch either during experimentation or through further data processing.…”

“…8 have been corrected to u L0 by using Eqs. (6) and (9) to account for nonzero flame thickness and flame stretch effects, respectively. The correction varied from À0.2 cm/s to À0.5 cm/s, with the magnitude increasing with / generally.…”

Laminar Burning Characteristics of Dilutedn-Butanol/Air Mixtures

“…Data without removing the stretch effects can well explain the large discrepancy in the reported laminar flame speed values from earlier investigations (Rallis and Garforth, 1980). There have several methods in determining the laminar flame speed, such as the stagnation flame method (Egolfopoulos et al, 1990;Ibarreta et al, 2005), the outwardly propagating spherical flame method (Bradley et al, 1996;Gu et al, 2009), and the flat and one-dimensional flame methods (Bosschaart et al, 2004;de Goey et al, 2007). The combustion bomb method is the most relevant to spark-ignited flame propagating flame in internal combustion engines, especially at high pressures and temperatures (Law et al, 2004).…”

Experimental investigation of very rich laminar spherical flames under microgravity conditions

“…These studies have focused on the determination of the laminar burning velocity and the onset of instabilities for pressures of up to 60 bar and equivalence ratios ranging between the flammability limits [3,9,11,12]. Despite their practical importance, experimental data for combustible mixtures that contain liquid fuels at ambient conditions, for example n-heptane and iso-octane, are rather scarce.…”