Turbulence phenomena at free surfaces

✍ Scribed by J. T. Davies

• Publisher: American Institute of Chemical Engineers
• Year: 1972
• Tongue: English
• Weight: 456 KB
• Volume: 18
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690180131

✦ Synopsis

Gas absorption by eddies a t the free surface of a strongly turbulent liquid is interpreted quantitatively in terms of the Levich approach. The mass transfer coefficient is calculated to vary as Re to o relatively high power (1.3 to 1.5).

Experiments on free turbulent jets of liquids in gas are in generol accord with this theory.

For turbulent films of liquids flowing over large roughness elements in "wake-interference" flow, the turbulence is anomalously effective in promoting gas absorption. Traces of surfoce-active agents suppress the surface renewal. This is analyzed theoretically: the results compare favorobly with gas-absorption for stirred cells and flow experiments over smooth plates. For "wake-interference" flow over rough plates, the reduction in the rate of gas absorption by surface-active material is more pronounced than predicted for ordinary turbulence. But even in the presence of a surface-active agent, the roughness still giver an advontage in mass transfer rates as compared with smooth plates.