Estimation of air entrainment and aeration efficiencies of weirs using genetic expression programming

Abstract

The concentration of dissolved oxygen is an important indicator of water quality because aquatic life lives on the dissolved oxygen in the water. A free overfall jet from a weir plunging into downstream water causes entrainment of the air bubbles if the free overfall jet velocity exceeds a certain critical value and hence aeration occurs. This paper investigates the free overfall jets from triangular sharp−crested weirs and their effect on the air entrainment rate and the aeration efficiency. The artificial neural network models, multi nonlinear and linear regression equations were obtained for the triangular sharp−crested weirs relating the air entrainment rate and the aeration efficiency to drop height, discharge, and angle in triangular sharp−crested weir. There were good agreements between the measured values and the values obtained using the artificial neural network and multi nonlinear regression models.

Efficiency of the Nam Theun 2 hydraulic structures on water aeration and methane degassing

“…The overall change in oxygen concentration over time in a water body as the body travels through a hydraulic structure can be expressed as (Baylar et al, 2009) The predictive relations assume that Cs is a constant determined by the water−atmosphere partitioning. If that assumption is made, Cs is constant with respect to time, and the DO transfer efficiency (aeration efficiency), E may be defined as Gulliver et al (1998):…”

“…Tropical fishes generally have a higher tolerance of low DO. Nevertheless, DO that remains below 1 mg.L -1 (and corresponding DO saturations equivalent tõ 10% at 20°C) for a few hours can affect biodiversity and generally result in large fish kills (Baylar et al, 2009). Studies of the direct effects of methane on water organisms are very limited.…”

“…To maintain DO and gas concentrations compatible with aquatic life and other uses, many solutions have been tested to supply DO (namely aeration; Baylar et al, 2009). Solutions range from hypolimnetic oxygen injection, reservoir clearing and selective withdrawal to the construction of dedicated hydraulic structures like weirs or baffle blocks.…”

“…DO transfer occurs when air is entrained into the flow in the form of a large number of bubbles. These bubbles greatly increase the surface area available for mass transfer (Baylar et al, 2009). Very few man-made reservoirs are equipped for aeration with respect to the total number of reservoirs throughout the world.…”

Saving on Energy of and Determining the Best Location of Water Treatment Plant along Rivers Depending on the Effect of Broad Crested Weir on Dissolved Oxygen Concentrations in Water

“…As for the studies done on the effect of weirs on air entrainment; the study done by Baylar was examining the free overfall jets from triangular sharp-crested weirs and their effect on the air entrainment rate and aeration efficiency. [3] Another study done by Kibel was investigating the effect turbine installation on dissolved oxygen concentrations within the weir pool. [4] .As for the studies done on the direct effect of hydraulic structures on dissolved oxygen concentrations in water, was the study done by El Baradei.…”