Ruben's tube was developed German physicist Heinrich Rubens in 1905 as a means of demonstrating the relationship between sound waves and pressure waves. A perforated tube is created in which one end of the tube is sealed with a flexible barrier. A speaker is placed against the flexible boundary and the tube is filled with a flammable gas. The sound frequencies of the speaker produce pressure waves in the gas which can be visibly observed in the flame heights when the gas is ignited.
Further Information on Ruben's tube history and construction can be found at the following links:
I did not put a great deal of research into this project outside of compiling a hardware list. Differences I've noticed between my construction and many others include:
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I used a short, 6" diameter tube while many others use a longer, 2.5" diameter tube
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I used a camp sized propane tank with a small diameter hose compared to many others using grill sized propane tanks and hardware
Result: It worked....well enough for test 1
Current Considerations and Changes
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Increase flow rate of propane to tube with larger hardware
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Research relationships between hose placement and number of hoses
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Procure not blown-out speaker
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Replace (now broken) wooden flange, preferably with something non-flammable
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Research effects of perforation diameter
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A way to ignite flames remotely
Current Flaws
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Soft tap on diaphragm enough to extinguish all flames
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Windy conditions problematic to keeping flames lit
Future Explorations
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How does tube/speaker diameter effect modal shapes in flame? Would larger diameter continue to be base sensitive while smaller diameter show stronger treble relationship?
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Other mediums to act as the tube. Could a rock be used to provide an organic aesthetic to this demonstration?
Ruben's Tube
Personal Project
Skills: Pipe Soldering, NPT threads differ from US and metric