Photo Contest
2022 Photo Contest -Beautiful Flames- The HIGHEST AWARD
Chrysanthemum Flame
DELFIN, Jerric1, GUO, Feng1, HASHIMOTO, Nozomu1, FUJITA, Osamu1
1 Hokkaido University
Explanation
OThis flame was formed from the interaction between acoustic vibration and downward propagating flame in the combustion tube of 5cm diameter and 71cm long. The combustion tube is half-open at the top end, ignition side. NH3/O2/N2 mixture is used as the tested gas with Φ=0.6 and designed SL?15cm/s. After ignition, a curved flame was planarized by acoustic standing waves that eventually form the cellular and corrugated flame undergoing parametric instability. During parametric instability, the flame oscillates twice the period of the acoustic standing wave that leads to turbulent flame propagation. The picture is one moment of the cellular and corrugated structure before the transition to turbulent motion, taken from the bottom view. It seems like a blooming chrysanthemum with the orange color of ammonia flame.
Camera: FASTCAM Mini UX100; Lens: VS-50085/C 50mm, F/0.85
F-number: F/0.85; Frame Rate: 2000 fps at 1280×1024 pixel resolution
Details of the experimental apparatus are described the following papers [1]
[1] Ajit Kumar Dubey, Yoichiro Koyama, Nozomu Hashimoto, Osamu Fujita, Acoustic parametric instability, its suppression and a beating instability in a mesoscale combustion tube, Combustion and Flame 228 (2021) 277-291, DOI: https://doi.org/10.1016/j.combustflame.2021.02.006
2022 Photo Contest -Beautiful Flames- The MERIT AWARD
August iris flower listening to the song of flame
TOSA, Naoko1, PANG, Yunian1, NAKATSU, Ryohei1, HAYASHI, Jun2
1 Art Innovation Tosa Laboratory, Disaster Prevention Research Institute, Kyoto University
2 Energy Conversion Science, Department of Energy Science, Kyoto University
The photograph shows a train of methane/air diffusion flames with a different flame length derived by the standing wave in the flow channel (Rubens tube). Vertical/horizontal flipped image was overlaid to emphasize the corresponding to pressure distribution of the standing wave and the flame length. On the right side of the image, an iris flower with barrier discharge is placed. An august iris flower, which is listening to the song of flame, expresses the beauty of energy. The burner used for this photo has a rectangular channel of approximately 1 m. The speaker with a thin rubber sheet was placed on the opposite side of the fuel inlet. The frequency of the sound from 650 Hz to 960 Hz can show a beautiful waveform of the diffusion flame train. The barrier discharge on the iris is obtained by supplying a sine wave with a maximum voltage of 32 kV and 7 kHz between the water-filled acrylic tank and the iris flower.