Laser Doppler Velocimetry

This technique involves adding small tracer particles with a diameter below 1 micrometre (e.g. oil) to the flow. These particles scatter light from two laser beams that are projected into a small measurement volume. In this volume, the laser beams interfere with each other to produce interference planes (tiny planes of light, one behind the other). As the particles fly through these planes, they reflect the light, and the frequency of these light flashes can be used to calculate the velocity if the distance between the interference planes is known. For our work, we use a two-component LDV system, which is commercially available, in collaboration with four other institutes at the Faculty of Mechanical Engineering. A small one-component LDV system is used for students' laboratory and outdoor measurements. The following picture shows the two-component LDV setup.