Ultrasound Measurement Technique for Validation of Cryogenic Flows

An ultrasound sensor system based on the transmission-mode approach is developed to enable the monitoring and sensing of cryogenic liquids and gases—especially gaseous bubbles and gas-liquid interfaces in liquid nitrogen (LN2). Common sensors do not meet requirements of cryogenic and microgravity-environments. Therefore, a special encapsulation design for the optimization of the electrical connection and the mechanical coupling of the ultrasound sensors is needed. The ultrasound system is qualified in LN2 and is able to measure bubbles (size and location) and fill levels with a high spatial resolution in a submillimetre range and a sampling rate of more than 500 Hz