The effect of a cold temperature valley on pulsating flame spread over propanol

Scaling Analysis on Pulsating Flame Spread over Liquids

“…We found a dual pulsation structure for flame pulsation, consisting of a main pulsation of about 0.5 to 1 Hz, and a subpulsation of about 5 to 10 Hz [29]. The main pulsation generated and eliminated a cold temperature valley in the liquid surface ahead of the flame [28]. Based on these experimental data, we proposed a pulsating flame spread model [28] involving subsurface layer circulation and a surface wave.…”

“…The 50 mW He-Ne laser beam passes through a tracing paper and is changed into scattered light in order to remove any distortion from the shadowgraph. For flow visualization and velocity measurement in the liquid phase, a particle-track laser-sheet (PTLS) technique was used [28], with a high-speed video camera (125 frames/sec, 20 mm × 20 mm field of view). PTLS can measure profiles of both streamlines and the twodimensional velocity with significantly fewer particles and nearly instantaneously.…”

“…The main pulsation generated and eliminated a cold temperature valley in the liquid surface ahead of the flame [28]. Based on these experimental data, we proposed a pulsating flame spread model [28] involving subsurface layer circulation and a surface wave. Figure 1 shows a series of photographs of a pulsating flame and schematic side views of liquid and gas flow structures for the four steps of the cycle (a)-(d).…”

“…Over the past ten years, a series of experimental studies of flame spread over liquids has been conducted [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], creating a rich experimental database. With six different experimental techniques (laser sheet particle tracking, smoke tracing, single and dual wavelength holographic interferometry, infrared thermography, and high-speed photography), we measured the detailed thermal, fluid dynamic and chemical structures of both gas, and liquid phases near the flame's leading edge to understand the mechanism of pulsating flame spread [26][27][28][29].…”

“…With six different experimental techniques (laser sheet particle tracking, smoke tracing, single and dual wavelength holographic interferometry, infrared thermography, and high-speed photography), we measured the detailed thermal, fluid dynamic and chemical structures of both gas, and liquid phases near the flame's leading edge to understand the mechanism of pulsating flame spread [26][27][28][29]. We found a dual pulsation structure for flame pulsation, consisting of a main pulsation of about 0.5 to 1 Hz, and a subpulsation of about 5 to 10 Hz [29].…”