Characterization of flow turbulence induced by a bubble-plume in large-scale experiments

GARCÍA, C.M.; GARCÍA M.H.

Lake Placid, New York, USA.

Conferencia; Hydraulic Measurements and Experimental Methods Conference; 2007

Environmental and Water Resources Institute of ASCE (EWRI) y International Association of Hydraulic Engineering and Research (IAHR).

The present work provides a detailed set of experimental data quantifying the flowturbulence and mixing induced by bubble-plumes in large experimental facilities withcombined-sewer-overflows under non-stratified conditions. The acoustic Dopplervelocimeter technique was selected as the optimum technique to accurately characterizethe flow turbulence induced by bubble-plumes in large facilities with presence ofcombined-sewer-overflow. The turbulence characterization was performed on basis ofdata recorded in an intermediate region of the tank away from the plume, water surface,walls, and bottom with a homogenous behavior of the turbulence parameters. Based onthe recorded velocity signals, different scale-dependent turbulence processes induced bybubble-plumes in large facilities were identified and their contributions to theturbulence parameters were quantified. Finally, the extensive set of experimental datawas summarized in a set of dimensionless plots which can be used to conduct apreliminary design of coarse-bubble diffuser for reservoir mixing. They can also beused for the validation of numerical models of bubble-plume systems used in the designof these combined-sewer-overflow reservoirs. The analysis of these plots shows that themore energetic the bubble plume (based on the geometry of the tank and in the injectedair discharge), the higher the fraction of energy dissipated by turbulence in theintermediate region of the tank away from the plume, water surface, walls, and bottom.