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.