This image, taken from above looking vertically downwards, captures a turbulent premixed propane flame jet impinging upon the surface of a still pool of water. Careful inspection of the image reveals water droplets being thrown up above the flame. Rapid cooling of the combustion front due to proximity with water leads to high amounts of soot formation relative to the apparently leanness of the premixed flame.

Image captured using a Canon EOS 6D Mark II with a EF 50mm f/1.8 STM lens, shot at ISO 500, f/2.8, and a 1/4000 second shutter speed. Adobe Lightroom Classic denoising algorithm applied to reduce low-light/high-ISO related noise.

Satisfaction of the Combustion Experiment Guidelines:

• The whole session was conducted in a non-combustible location: The flame never reached beyond the edges of the pool water, which was itself surrounded by a large concrete pool deck, which was swept clean of any potentially flammable debris.
• Both a fire extinguisher and sand were on hand, as well as a water hose and of course, the pool water itself.
• There were, at all times, 5 individuals present during the experiment. Generally, one held and operated the torch, one operated the camera, and the remaining three observed the process, ensuring nothing unexpected went uncaught. All participants had cell phones, and were prepared to give directions to the shoot location.
• No PPE was deemed appropriate for this shoot. The fuel is contained throughout the process until it is burned, so there is no need for fuel handling PPE. The burner nozzle is attached to the control valve by a long pipe, and is kept somewhat cool by the inflow of ambient air through the back of the nozzle, and so there was no need for thermal protection PPE.
• Shielding was not appropriate for this setup, as the subject was large enough and cool enough that the camera and operator were not at risk of being burnt. Similarly, the burner operator is always several feet behind the nozzle and flame. Additional participants were physically distant from the flame due to its proximity over the pool: all individuals were on the pool deck at all times.