Analysis of turbulent premixed flame structure using simultaneous PIV-OH PLIF

Abstract

In the present study, we used a simultaneous PIV-OH PLIF measurement to acquire the strain rate and the chemical intensity and suggested a new combustion phase diagram. This simultaneous measurement was used to analyze the flame structure and to classify the combustion regimes of the opposed impinging jet combustor according to the change of the orifice diameters at the pre-chambers. The shear strain rates were obtained from the velocity measurement by PIV to represent flow characteristics and the OH radical intensities were obtained from OH PLIF to indicate the flame characteristics. When the strain rate and OH intensity at each point of the measurement zones are plotted at the strain rate-chemical intensity diagram, the distribution of each case showed the characteristics of each flame regime. The change of combustor condition made different distribution in the combustion phase diagram. As the orifice diameter of the pre-chamber decreases, well-mixed turbulent flames are produced and the combustion phase is moved from the moderated turbulence regime to the thickened reaction regime.

Blowoff mechanism of two dimensional bluff-body stabilized turbulent premixed flames in a prototypical combustor

“…The sequence of events approaching blowoff and the associated flameflow interactions are shown to be similar for this two dimensional configuration with larger length and velocity scales, suggesting the general validity of this description. Validation was performed based on the observed interaction of flame and fluid dynamics obtained by time-resolved chemiluminescence imaging and simultaneous PIV and hydroxyl radical PLIF imaging, similar to the techniques reported in [13][14][15]. The experiments show that near blowoff, extinction of the flame along the shear layers leads to reaction of fresh mixture within the recirculation zone, which normally contains combustion products for a stably burning flame away from blowoff.…”

Investigation of Flame Evolution in Heavy Oil Boiler Bench Using High-Speed Planar Laser-Induced Fluorescence Imaging

“…In recent years, the planar laser-induced fluorescence (PLIF) technique, a modern optical diagnostic method with high spatial and temporal resolution, has developed rapidly in the field of combustion diagnosis [1][2][3]. Many experimental results can be found in the literature regarding both qualitative characterizations of flame structure and quantitative measurements of interesting features, such as concentration, temperature, and velocity [4][5][6][7][8]. However, most successful applications are confined to the ideal environment of the laboratory, regardless of the impact of the external environment, i.e., variables such as temperature, humidity, and vibration on the PLIF system.…”