How does the kettle whistle? Apparently this is one problem that hasn’t been solved in 100 years, until now. Phys.org leads with this:

Researchers have finally worked out where the noise that makes kettles whistle actually comes from – a problem which has puzzled scientists for more than 100 years.

Seems hard to believe.

Writing in the October issue of the academic journal, The Physics Of Fluids, two Cambridge University researchers claim to have solved the conundrum, and in the process developed the first accurate model for the whistling mechanism inside a classic stove kettle.

Perhaps reassuringly for those who never felt that this was a significant problem, the ramifications reach far beyond kettles themselves. 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.

“The effect we have identified can actually happen in all sorts of situations – anything where the structure containing a flow of air is similar to that of a kettle whistle,” Ross Henrywood, from the University of Cambridge Department of Engineering, and the study’s lead author, explained.

“Pipes inside a building are one classic example and similar effects are seen inside damaged vehicle exhaust systems. Once we know where the whistle is coming from, and what’s making it happen, we can potentially get rid of it.”

Henrywood carried out the research for his fourth-year project as part of his engineering degree, under the guidance of his supervisor, Dr Anurag Agarwal, a lecturer in aeroacoustics. Drawing on previous research by Agarwal, which identified the source of noise in jet engines, the pair were able to show how sound is created inside a kettle as the “flow” of steam comes up the spout.

The abstract of the paper is here.