A spraying apparatus includes a convergence chamber having a large end and a small end; at least two water inlets provided in the large end of the convergence chamber, each water inlet having a central axis and the at least two water inlets being arranged at convergent angles to each other so that the central axes converge in free space within the convergence chamber; at least one air intake provided in the convergence chamber between the large end and the small end; and a rectifier opening including a throat provided at the small end of the convergence chamber; and a spraying opening, the rectifier opening having a cross-sectional area that continuously increases outwardly from the throat to the spraying opening, and the throat having a cross-sectional area that is one to three times greater than that of a total cross-sectional area of the at least two water inlets.