Aeration characteristics of a rectangular stepped cascade system.

Aeration experiments, maintaining nappe flow conditions, were carried out on a rectangular stepped cascade of total height 3.0 m to determine the total number of steps, slope of the entire cascade and hydraulic loading rate at which maximum overall aeration efficiency occurs, keeping the surface area of individual steps constant. Based on dimensional analysis, the overall aeration efficiency at standard conditions (E(20)) was expressed as a function of square of total number of steps (N(2)) and dimensionless discharge (d(c)/h), where d(c) and h represent critical depth in a rectangular prismatic channel and individual step height respectively. An empirical equation with E(20) as the response and N(2) and d(c)/h as the independent parameters was developed based on the experimental results subject to 36