In the Laser Doppler Velocimetry Lab, a laser and a computer are used to measure the velocities of the liquid stream.
The Laser Doppler Velocimeter is the most advanced experimental technique yet devised for measure fluid velocities. The problem traditionally encountered when trying to make fluid velocity measurements is that taking the measurement usually disturbs the flow and alters the velocity that one is attempting to measure. The insertion of a metal probe into the stream, for instance, changes the flow pattern. Because the Laser Doppler Velocimeter uses laser light to make the velocity measurement the flow is completely unaffected.
The system consists of a 10 milliwatt Helium-Neon Laser, a frequency shifter that converts measured frequencies to velocities and a high speed data acquisition system. The data is analyzed by computer software that allows for time-dependent analysis of the velocities. The velocimeter also has a Bragg cell that enables the system to detect flow reversal.
Mechanical Engineering Students get the opportunity to use the laser velocimeter in Professor Laoulache's upper level technical elective Laser Doppler Anemometry.