[hotrod]

I think one of the issues here is simply a choice of word usage. Most of the discussions on this topic throw around general terms like " an insignificant amount of water is evaporated" --- what I consider insignificant someone else might consider to be quite large or vise versa.

As you know from the water fog cooling systems used in the desert SW, even in high temps, brutally low relative humidities and high temperatures it takes a signifiant amount of time to evaporate a water mist completely. In the NACA studies even in cases where the water mist passed through a turbocharger compressor, only a fraction of the water was evaporated, and dropplets were present down stream from the compressor..

My personal preference is to go for maximum evaporation. Your never going to get it, but there are several hints out in the NACA studies and in other sources that applications that do not give the water mist ample travel time to mix and evaporate do not achieve as much max power potential as systems that place the nozzles well back from the throttle.

No matter what you do, a lot of the water will arrive in the cylinder as small dropplets. If for no other reason than to minimize variations in water transported to the various cylinders, I think the mist size should be as fine as practical. In the real world it is difficult to get mists smaller than about 50 micron at reasonal pressures and without having nozzles that are prone to clogging. For that reason alone the 50 micron dropplet range is probably about as good as your going to get in a practical system.

If you get dropplets much larger than the 80 micron range then you get into problems with the water getting centrifuged out of the air stream as it transits the intake manifold. I believe that is why that target range is frequently mentioned.

Larry