Two-dimensional temperature field measurement of a premixed methane/air flame using Mach-Zehnder interferometry

An optical visualization of laminar premixed methane/air flame is carried out in order to investigate the flame structure and its isotherm pattern in a slot burner. Mach-Zehnder interferometry technique is used to obtain an insight to the overall temperature field. The slot burner with large aspect ratio (L/W), length of L=60 mm and width of W=6 mm was used to eliminate the three-dimensional effect of temperature field. The effects of Reynolds number ranging from 100 to 800 and equivalence ratio ranging from 0.7 to 1.4 on thermal flame height (HT), structure and isotherm patterns are investigated. The present measurement reveals that the variation of maximum flame temperature with increment of Reynolds number is mainly due to heat transfer effects and is negligible. While the equivalence ratio has a noticeable effect on flame temperature. In addition, maximum temperature occurs at stoichiometric condition. Thermal flame height augments by Reynolds number increase while its increment at rich mixture is higher and the effect of Reynolds number at lean mixtures is almost negligible. The results also show that the effect of Reynolds number is more than the equivalence ratio on the thermal flame height. For validation of experimental results from Mach-Zehnder Interferometry, K-type thermocouples are used at peripherally low and moderate isotherm lines.