ADV MEASUREMENTS OF TURBULENCE - CAN WE IMPROVE THEIR INTERPRETATION

A simple technique to reduce the Doppler noise influence on measuremen ts of turbulence using the Acoustic Doppler Velocimeter (ADV) is devel oped, and basic relationships to estimate turbulence characteristics u sing information about the Doppler noise are derived. The procedure in volves, firstly, measurement of instantaneous velocities in the flow u nder consideration; secondly, measurement of the Doppler noise compone nts in still water taken from the Bow investigated (with the same velo city range setting that was used in turbulence measurements); and thir dly, estimation of turbulence characteristics using both sets of measu rements and relationships developed in the paper. The technique was te sted for three typical environments (water storage basin with silty wa ter, laboratory flume with water containing seeding material of neutra lly buoyant hollow glass spheres with a mean size around 8-10 mu m, an d outdoor flume with natural water containing air bubbles and organic particles). It was shown that the Doppler noise can change the measure d turbulence characteristics significantly, even for high-level turbul ence flows.