Ultrasound volume flow measurement

Patent Granted There are two main types of Ultrasonic flow meters: Doppler and transit time. While they both utilize ultrasound to make measurements and can be non-invasive (measure flow from outside the tube, pipe or vessel), they measure flow by very different methods. Ultrasonic transit time flow meters measure the difference of the transit time of ultrasonic pulses propagating in and against the direction of flow. This time difference is a measure for the average velocity of the fluid along the path of the ultrasonic beam. By using the absolute transit times both the averaged fluid velocity and the speed of sound can be calculated. Using the two transit times t_{up} and t_{down} and the distance between receiving and transmitting transducers L and the inclination angle \alpha one can write the equations: v = \frac{L}{{2\;\sin \left( \alpha \right)}}\;\frac{{t_{up} - t_{down} }}{{t_{up} \;t_{down} }} and c = \frac{L}{2}\;\frac{{t_{up} + t_{down} }}{{t_{up} \;t_{down} }} where v is the average velocity of the fluid along the sound path and c is the speed of sound.