Noncontact Flow Rate Sensor Using Laser Ultrasonics 33a

Several types of advanced reactors are cooled with high-temperature liquid metal or molten salt flows. There is a critical need to measure the flow velocity in flow channels for test purposes, and eventually in operational reactors. In conventional, transducer-based ultrasonic flow sensors, waves traveling in both the upstream and downstream directions give a measure of shift in the frequency or transit time to determine the velocity. The effort proposed here will replace these contact transducers with laser-based generation and detection instruments. This noncontact sensing will avoid the many practical problems associated with contact transducers when implemented on high-temperature flows. In Phase I the feasibility of the proposed sensor will be demonstrated by measuring water flow and room- temperature liquid metal flows in a diagnostic channel. It will also be demonstrated that small shifts in the time-of-flight of ultrasonic waves can be measured with sufficient accuracy to determine the flow velocity.The broadest commercial market will be for flow monitoring in hot process piping in the chemical processing and petroleum refining industries. Current commercial ultrasonic flow meters are restricted in operating temperature by the risk of transducer damage. The noncontact laser ultrasonic flow meter to be developed in this project has no temperature restriction. Individual heads can be installed permanently if required, and interrogated on demand. Alternatively, multiple measurements across a flow profile can be made with a free-standing head.