A frictional pressure drop occurs when air flows over a surface, pulling the airstream towards it. If the pressure at the surface is artificially increased slightly, by an external agency, the airstream can be persuaded to leave the surface and seek a more stable pattern of flow. The techniques of fluidics exploit this so-called ‘Coanda’ effect to provide a simple manner of switching an airstream between two stable configurations by using small pressure differences, no moving mechanical parts being involved. Fluidic switching has been used to a limited extent in air conditioning in the past but has not yet been extensively applied.
Posted in Engineering Fifth Edition