The transfer of oxygen from air entrained by jets entering a free water recipient

Abstract

A detailed study has been made of the oxygen transfer resulting from the air entrained into a free water recipient by water jets. Particular attention has been paid to various free falling jets entering a pool for a variety of conditions of this pool, also to a guided jet terminating in the formation of an hydraulic jump. These features are common to a number of hydraulic structures. An extensive laboratory programme has been conducted, the effect of all important hydraulic variables has been investigated together with water quality effects, in particular the effect of dissolved salts. Dimensionless correlation equations have been developed and some success has been achieved in determining the modelling laws governing the oxygen transfer in an air entrainment situation. Modelling according to the Froude law of similarity has shown that the oxygen transfer expressed as a deficit ratio varied as a simplified function of the scale. For the first time, the laboratory measurements of oxygen transfer due to a free falling jet entering a free water recipient have been successfully correlated with data received for a number of prototype dam and weir structures. Similar success has been achieved in correlation with published laboratory work on free overfall weirs, and a wider range of applicability to multi crested and cascade weirs has been shown subject to certain conditions.