| 總結: | In this work, an experimental investigation of the main morphological parameters of buoyant methane laminar diffusion flames, including flame width and flame volume, is carried out under various sub-pressures (20-100 kPa). Quantitative models for flame width and volume are derived and compared against experimental results by assuming a cylindrical flame shape. The methane buoyant laminar diffusion flames are produced using a circular burner with an inner diameter of 8 mm, and the fire tests are conducted in a low-pressure chamber with inner dimensions of 3 × 2 × 2 m. The mass flow rate in the current study ranges from 2.988 mg/s to 8.365 mg/s. The experimental results show that air pressure impacts flame appearance. When the pressure is increased, it is noted that the flame transitions from steady flames or tip-flickering flames to sinuous meandering flames or even bulk-flickering flames. Additionally, the flame width decreases with increasing ambient air pressure for steady and tip-flickering flames, and the results show that the flame width is inversely proportional to the 1/3 power on the ambient pressure, Wf∼P1/3. For bulk-flickering flames, the flame width is independent of ambient air pressure, Wf∼P0. Also, the flame volume decreases with increasing air pressure at relatively small mass flow rates, and the measured flame volume is inversely proportional to the (0.43−0.55) power of the ambient pressure. Finally, based on dimensionless analysis, prediction models for flame width and volume are proposed, which are Wf∗=0.388Φ−0.51 and Vf∗=2.177×10−4Φ−0.85. The correlated results successfully unify the current experimental findings.
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