A laser fluorescence anemometer for water tunnel flowfield studies

Successful proof-of-concept experiments carried out using the laser fluorescence anemometer (LFA) in the NASA Ames-Dryden water tunnel are described. The instrument provides for flow visualization and the nonperturbing simultaneous measurement of instantaneous velocity and dye concentration in complex mixing flowfields. The instrument was used in experimental studies of vortex flowfields designed to determine the mechanisms and feasibility of controlling vortex breakdown by introducing relatively low rates of jet blowing along the vortex core. Measurements show that the LFA can provide new insight into the structure, entrainment, and control of mixing vertical and shear layer flows. It is shown that vortex breakdown can be controlled and eliminated by relatively small amounts of jet blowing along the vortex axis