Domestic & Industrial cyclone separators

Cyclone separators use swirling flows to separate particles from air. This flow produces oscillations that manifest themselves as unwanted high-pitch noise in vacuum cleaners and result in structural damage in large industrial separators.

The oscillations can be thought of a wobbly spinning top. When the axis is vertical it spins smoothly but when the axis is off-vertical then the top wobbles about the axis.
Looking down with a high-speed camera into cyclone, we can see the wobbly flow
These oscillations make a high-pitched sound that we call a “cyclone hum”.

We have developed a new experimental technique to model and characterise the cyclone hum. Dyson are now using the technique to design the next generation of vacuum cleaners.

T. Grimble, A. Agarwal: Characterisation of acoustically linked oscillations in cyclone separators. In: Journal of Fluid Mechanics, vol. 780, pp. 45–59, 2015, (15pp).