Smoke ring
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A smoke ring is a visible circular vortex in the air. It can be generated by humans, but also by volcanoes.
A smoke ring is a vortex in the shape of a torus with a flow direction around the ring body, i.e. a vortex ring that is visible because of the smoke. The phenomenon has its own motion that runs along the ring axis. The inner speed is always higher, it forms a self-contained flow and thus energy system. While the cloudiness in the environment usually disappears quickly, the smoke particles in the ring are virtually trapped.
Such a ring can, for example, have a size of 25 m with a ring thickness of 3 m (“designed” steam emission of a power plant) and a smoke ring of 200 m has been observed at Etna .
The parameters are relatively constant, at most a certain increase in size is observed. Depending on the conditions, such a ring can be preserved for several minutes.
With a certain amount of practice, smokers can produce such rings, whereby an approximately circular mouth opening is required. In addition, a small amount of air is expelled by gently moving the jaw, tongue or lungs. The smoke, which is initially mostly in the lungs, is only used to make the result visible.
A similar effect can also be achieved by underwater divers who create ring-shaped air bubbles that then rise to the surface of the water. Dolphins can sometimes do this too .
Situations in which smoke rings occur are e.g. B .:
- targeted exhalation of a smoker
- in the case of explosion-like, directed deflagrations , e.g. B. when swallowing fire
- occasionally in a nuclear explosion and on volcanoes
Smoke ring generator
The targeted reproduction of this vortex is achieved using a so-called smoke ring generator , also known as a smoke ring chamber or vortex generator . A kind of drum is used that has a hole in the middle on one side and the membrane on the other side is struck. A pressure wave is created which escapes through the hole. The air flowing around the edge from all sides creates a very uniform turbulence at the edge of the hole. By previously filling the drum with smoke, smoke rings can be created. Without smoke, invisible ring vortices are created, which of course still have the same effect: the air vortex can be felt several meters away and can e.g. B. Blow out candles or blow away light objects.
A less complex method is the use of a 1.5 l PET bottle, which is very likely to emit one or even several smoke rings when it is filled with smoke.
Web links
- Smoke rings on the Etna volcano
- Smoke rings on the Stromboli volcano
- Video with different air and smoke rings
- Video: smoke rings . Institute for Scientific Film (IWF) 2004, made available by the Technical Information Library (TIB), doi : 10.3203 / IWF / C-14856 .
Individual evidence
- ↑ ( Page no longer available , search in web archives: https://www.youtube.com/watch?v=LaIzbtc8mHc&feature=youtu.be )