Velocity measurement in a fluid using LDV: low-cost sensor and signal processing design

Laser Doppler Velocimetry (LDV) has been widely used for many years in fluid mechanics to measure particle velocity. However in most applications, in industrial processes for example, such a system is often too expensive. This paper discusses a technique based on the use of an analog phased-locked loop and an analog integrator system for processing LDV data to infer particle velocity. This method appears to be suitable for designing low-cost integrated LDV sensors. A SIMULINK^® program has been written in order to validate the method for velocities in the 10 mm/s to 80 mm/s range. Finally, the performance of the estimator is illustrated by Monte-Carlo simulations obtained from a synthesized Doppler signal.