How can the Water kettle whistling?

The mystery behind the whistling sound of water kettle finally solved. Two scientists from the University of Cambridge in England found how can the kettle whistling out loud when water was boiling in it. Beforehand this puzzle remained no answer for a century.

The spinning steam creates a vortex which begins to whistle. (Picture from: http://www.telegraph.co.uk/)

So far, it has been known that the sound comes from the kettle whistle that attached to the spout (the tip of a small funnel-shaped kettle to pour the water). But what about the mechanisms of emergence of whistling sound that often deafening was still elusive.

Ross Henrywood and his mentor, Dr. Anurag Agarwal, an aeroacoustics lecturer, managed to answer this riddle after followed of Agarwal initial research, which is recognized the source of the noise on jet engines.

"The sound produced by the water kettle comes from the flow of steam that emerging through the spout," said Henrywood, as quoted from the pages of the university site on Thursday, November 21, 2013.

The aeroacoustics of a steam kettle. (Picture from: http://www.neatorama.com/)

The secret is in the whistle on the spout. The whistle consists of two layers adjacent metal plates, thus forming a narrow cavity between them. Each plate has a hole at its center, which allows water vapor to pass.

In their tests, the two scientists made a simple kettle whistle as a model. Later they circulate air at various speeds through the whistle. Every sound that produced is recorded.

As a result, at a certain speed, the flow of water vapor trapped in between the two plates forming small eddies and the air around it vibrate. At a certain frequency, the flow of discharged water vapor produces a sound like whistling.

The longer the water boils, the higher the vapor pressure, more shrill the whistling sound that produced by the kettle. High-low of the whistling sound is also influenced by the length of the spout. The shorter the spout, the higher the whistling sound. *** [EKA | FROM VARIOUS SOURCES | TELEGRAPH | MAHARDIKA SATRIAHADI | KORAN TEMPO 4411]

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