October 25, 2013 4:08 pm
We all know the distinctive whistle of the tea kettle—but what actually produces that sound?
Turns out there are some interesting aeroacoustics involved, and it’s taken scientists until now to puzzle them out. In a paper published in the journal Physics of Fluids, researchers explained:
The whistle in a steam kettle provides a near-perfect example of a hole tone system, in which two orifice plates are held a short distance apart in a cylindrical duct. This setup leads to distinct audible tones for a large range of flow rates.
The workings of a tea kettle might seem like an obvious problem to look into. But no one—not even the British!—had come up with a good answer for what, exactly, was going on every single day in households across the world. The University of Cambridge explains that the team set up a series of experimental kettles to observe. Here’s what they found:
Their results showed that, above a particular flow speed, the sound itself is produced by small vortices – regions of swirling flow – which at certain frequencies can produce noise.
And it’s not just a silly piece of research either. Now that they know what makes the whistle they can stop it in other situations:
Using the knowledge gained from the study, researchers could potentially isolate and stop similar, but far more irritating whistles – such as the noise made when air gets into household plumbing, or damaged car exhausts.
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