Experimental Study on Aeration Performance and Bubble Characteristics of Inverted Umbrella Aerator

Abstract

In order to understand the aeration performance of inverted umbrella aerator and bubble characteristics in aeration tank under different conditions, and to reveal the internal relationship between bubble characteristics and aeration performance, an experimental bench of dissolved oxygen concentration and high-speed photography was built. Logarithmic oxygen deficit values were fitted under various conditions. The images captured by high-speed photography were processed, then the bubble characteristics were extracted accurately. It was found that the standard oxygen mass transfer coefficient increased linearly with an increase of rotational speed at a certain immersion depth, and increased firstly then decreased with a decrease of immersion depth when rotational speed was kept constant. The bubble size ranged from 0 mm to 1.59 mm under different working conditions, and the variation of the gas holdup was the same as the standard oxygen mass transfer coefficient when the rotational speed and immersion depth were changing. It was shown that bubbles play a leading role in the process of oxygen mass transfer and have a great influence on oxygen mass transfer rate.

Keywords

• aeration performance
• bubble characteristics
• inverted umbrella aerator
• standard oxygen mass transfer coefficient