A spray nozzle is usually designed to atomize a liquid stream of a given viscosity, at a known flow velocity. The hissing noise that can often be heard, may be up around 1000Hz.
This is similar to the frequency one listens for, to find leakage and is akin to what may be called "channel cavitation".
Basically, as flow goes passed a sudden change in diameter, from a small very high velocity flow path, and out into a substantially unlimited space a very high frequency stream of pressure disturbances breaks the flow into minute droplets.
If the flow rate falls, the high frequency is no longer created, and the liquid stream becomes a squirt or series of globlets and splodges.
Stabilizing flow with a flow fluctuation "damper" to within 5% of the nozzle design flow rate will normally ensure constant atomization.
UNDERSTANDING FLOW OR PRESSURE PULSATION
WAYS TO GO
Return to the top
Return to the Explanation index