ABSTRACT
A jet of air mixes at its periphery with the surrounding air of the space so that with increasing distance from its source the rate of airflow constantly increases and the velocity decreases. The contrast between velocity characteristics of jets and those of exhaust hoods is marked. A push-pull hood will control hot oil mist and smoke rising from a machine. The average velocity of the jet at its destination independent of any induced by the exhaust hood, may be significant. If the length-width ratio is not excessive, relative to the travel distance, the jet becomes circular by more rapid mixing and divergence at its longer boundaries. The force exerted by an air jet is the momentum per unit time. The velocity relationships in a jet issuing from a slot-shaped nozzle expanding against a parallel plane flanking its path are based again on McElroy's data.
