Velocity measurement using optical sensors

The work presents an investigation on the use of optical sensors for velocity measurement. The cross-correlation technique was used for this purpose. The sensors were placed upstream and downstream on a hydraulic flow rig in order to detect the flow of bubbles. The cross-correlation flowmeter measures bubbles' velocities by sensing the passage of some disturbance in the flow at one position, and measuring how long time (transit time) requires that disturbance to travel to the next point.