K. S. Baker Environmental Hydraulics Laboratory

In addition, LDV does not require calibration, is linear (measured Doppler frequency is directly proportional to the flow velocity), is sensitive only to the fluid velocity, and is completely insensitive to changes in fluid properties such as temperature and pressure. LDV systems are especially valuable for flow measurements in corrosive or high temperature environments, re-circulating and rough wall flows, restricted or confined spaces. Furthermore, LDV has excellent temporal and spatial resolution. The flow measurements are obtained using a three-component, three-color, sixbeam, frequency-shifted, non-orthogonally oriented laser Doppler velocimetry system, operating in an off-axis, back-scatter data acquisition mode. The entire LDV system in Kelso S. Baker Environmental Hydraulics Laboratory is mounted on a traverse table (TSI, Model 9500), that can be moved in three orthogonal directions by individual stepper motors. The specified accuracy and repeatability of spatial positioning of the traverse table is 2.5 microns. The LDV system is capable of measuring velocities of two channels (e.g. streamwise and vertical velocity components) with up to 1000 samples per second data rate with great accuracy.

Back to the facilities page

Back to the research page

3D LDV

Laser Doppler velocimetry, commonly called LDV, is a non-intrusive, optical technique, that is employed in measuring flow velocities. The non-intrusive nature is particularly beneficial in rough wall studies, as measurement uncertainty caused by probe interference is completely eliminated.