Water jet
Water jet
(OP)
If water is flowing through an orifice under pressure and forms a jet. Is there a way of predicting at what distance from the orifice the jet will cease to be a coherent stream and break up into small droplets. In my particular case the water is pressurised at 6000psi, the orifice is 0.003" diameter and the jet is vertically downwards





RE: Water jet
Are you trying to maintain coherence for as long as possible, or cause more rapid stream breakup? To get best coherence, use a long piece of capillary tubing and upstream flow straighteners, and have the tip of the tube ground to a taper, with a nice, clean, square edge at the exit. To get more rapid breakup, use non-circular orifices, or orifices with an overhanging "lip" on one side, and pre-swirl the flow (although there are regimes of flow where very small amounts of preswirl can help maintain coherence; most of us males have a daily proof of this phenomenon :). To really get rapid breakup, impinge two streams onto each other.
RE: Water jet
Looking for desciptions of Rayleigh breakup vs 1st & 2nd wind-induced & atomization regimes might help you along.
("Rayleigh breakup: Drop diameters are larger than the jet diameter. Breakup occurs many nozzle diameters downstream of nozzle.")
Hope this helps,
radAES