Study on Velocity Profile Measurement of Saturated Jet Flow by Air-coupled Ultrasound

An air-coupled ultrasonic sensor and velocity profiler are developed to measure the steam flow rate. The developed ultrasonic sensor can be adopted to measure the droplets since it has a round surface that can focus the ultrasonic beam with narrow width and high-intensity. Meanwhile the sensor has a matching layer which enables to reduce the acoustic reflection between the sensor and the air. A signal processing for eliminating the side lobe echo noise is installed in the air-coupled ultrasonic velocity profiler so that the steam velocity can be measured, successfully. The flow structure of steam jet is observed that the velocity boundary layer development and the main jet steam increase with the steam flow velocity. Therefore, it is revealed that the steam flow velocity could be measured by air-coupled ultrasound.