SOME ASPECTS OF AIR-ENTRAINMENT ITT FLOWING WATER A.

Abstract

, trrentrainment is a natural phenomenon observed in water flowing in a channel or discharging freely into the atmos-phere. The designs of sti.ctures like rapids, chutes, overfall spillways,, stilling basins are greatly influenced due to air-entrainment in flowing water. Various theories regarding air entrainment have been evolved, Theory advanced by Hall and modified by various authors, Is suitable for design of channels carrying non-uniform flow. The theory being of much practical importance, has been dealt with in rather greater detail. In the detailed study of any phenomenon,, precise mea-surements of the various quantities involved play an important role. Keeping this point in view, the electrical and the elec-tronic methods. of measuring alr.concentra-titan and SAF velocity-meter which is based on the electronic methods, for the measure-ment of velocity of aerated flow has been dealt with in greater detail. The air enters the water in the form of bubbles. The behaviour of bubbles is very similar to that of sediment in water. Useful results can be obtained by this analogy. An expression for the Or concentration along the vertical has been developed with the help of this analogy which follows the distribution law of isotropic turbulence fairly well.