Jet break-up and air entrainment by low velocity turbulent water jets

Correlating equations are developed for air entrainment by plunging water jets with velocities in the range between 2 and 5 m/sec. Energy considerations are shown to be a good basis for predictive equations. Two different situations are distinguished depending on whether or not the jet is near its break-up length; for jets produced by nozzles within which turbulence is fully developed the break length is correlated by

Beyond 90% of the total break length the air entrainment produced by vertical jets from 2·85 to 10 mm diameter is given by

For shorter jets which are vertical or inclined, there is a length dependence which leads to the relationship, accurate within 15%, of