What are the equations for whistling in a convoluted tube?

In summary, the conversation discusses the equations governing the effects of whistling in a convoluted tube as air passes through it, which is also known as a cable management tube or used in medicine. The conversation also mentions the use of these tubes in toys and golf swing practice devices, and explains the aerodynamics behind how the tube produces sound. It is suggested to search for "Impinging shear flow instability" for more information on the subject.
  • #1
manjagu
3
1
Does anyone know what the equations governing the effects of whistling in a convoluted tube as air passes trough it are? I didn't know it was called this until today, but a convoluted tube is the real name for what many cable management tubes are. These tubes are also used in medicine for things like ventilators. You used to be able purchase large ones as a toys, which you could twirl around above your head. The faster you twirl them, the higher pitch whistle you could get out of it.

Thanks!
 
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  • #2
manjagu, Welcome to Physics Forums!

The toy you mention can be purchased here:
Whirlies
An introduction to whirled music
http://www.exo.net/~pauld/summer_institute/summer_day13music/Whirly.html

The convoluted tube that produces sound is also used as a golf swing practice device described in this patent:
Golf swing practice system with convoluted tube
http://www.patentgenius.com/patent/6503149.html

For an excellent description of how it works see this from the Exploratoruim:
Aerodynamics researchers in Japan put a whirly in a wind tunnel and used very tiny hot wire anemometers to measure the airflow near the corrugations.
They discovered that air flowing over two successive corrugations in the wall of the whirly experienced "impinging shear flow instability."
This is the same effect that makes a tea kettle sing. If you look at the spout of a teakettle you will see that it has two disks separated by a short gap, each with a hole in its center. When the air, or steam, flows through the first hole and then flows through the second hole it exits in vortices which cause oscillating pressure in the air, heard by the human ear as a whistle. The ridges in the whirly tube play the same role. As the air flows first over one ridge then over a second it tumbles into a vortex. The faster the air flows through the tube the higher the frequency of the sound produced by the vortex. When the frequency of the vortex matches one of the natural resonant frequencies of the tube it is amplified.
http://isaac.exploratorium.edu/~pauld/activities/AAAS/aaas2001.html

If you still need the exact numerical methods to describe this you may search for
“Impinging shear flow instability”.

Cheers,
Bobbywhy
 
  • #3
Thanks for the thorough response! Very helpful.
 

What is convoluted tube resonance and why is it important?

Convoluted tube resonance is a phenomenon that occurs when sound waves are reflected and amplified within a tube with a complex shape, such as a spiral or zigzag pattern. This can significantly enhance the acoustic properties of the tube, making it useful for applications such as musical instruments and sound amplification systems.

How does the shape of a convoluted tube affect its resonance?

The shape of a convoluted tube plays a crucial role in determining its resonance properties. A complex shape with many bends and twists can create multiple reflections and standing waves, leading to a more pronounced resonance effect. On the other hand, a simpler shape with fewer bends will have a less noticeable resonance.

Can convoluted tube resonance be controlled?

Yes, convoluted tube resonance can be controlled by adjusting the length and shape of the tube. By altering these parameters, the frequency of the resonance can be shifted, and the strength of the resonance can be adjusted. This can be useful for tuning musical instruments or designing acoustic systems with specific resonance characteristics.

What are some practical applications of convoluted tube resonance?

Convoluted tube resonance has many practical applications, including in musical instruments such as saxophones, French horns, and oboes, where it helps to produce unique and desirable sound qualities. It is also used in sound amplification systems, where it can improve the overall sound quality and volume. Additionally, convoluted tubes are used in some industrial processes, such as in heat exchangers and chemical reactors, to enhance fluid mixing and heat transfer.

Are there any drawbacks to convoluted tube resonance?

While convoluted tube resonance can be beneficial in certain applications, it can also cause unwanted noise and vibrations. In some cases, these vibrations can even lead to structural damage if not properly managed. Additionally, designing and manufacturing convoluted tubes can be more complex and expensive compared to straight tubes. Therefore, careful consideration must be given to the potential drawbacks when using convoluted tube resonance in a system.

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