Characteristics of Self-Aerated Flows

Characteristics of self-aerated flows in open channels are studied by dividing the flow into two zones: (1) wall turbulent zone; and (2) free turbulent zone. Theoretical equations developed for air concentration and velocity in the free turbulent zone, starting from the basic equations of motion and continuity are checked with experiments conducted in a tilting flume and the agreement between them is shown to be good. The terms air-water density and air-water velocity are defined and equations are presented correlating them with air concentration. In accordance with the new definitions, Halbronn's method of measuring air-water velocity is modified and used in the investigations. An empirical relationship between bulkage depth and mean air concentration is presented.