Velocity Measurement on Two-Phase Air Bubble Column Flow Using Array Ultrasonic Velocity Profiler

Two-phase flows can be encountered in a wide variety of industrial applications including a nuclear reactor, boilers, chemical reactor, etc. Bubble column is a simple and commonly used way to investigate two-phase flow due to their relatively simple construction and ease of operation. In the study of two-phase flow, the knowledge of gas and liquid velocities are required for better understanding of transport phenomena. Therefore, many measurement techniques have been developed such as LDV and PIV. However, those measurement techniques for velocity measurements require transparent test section and obviously fail if working fluid is opaque. To overcome this problem, there is another one technique, Ultrasonic Velocity Profiler (UVP), which can obtain the velocity information of both gas and liquid phases in non-transparent test section and opaque liquid. Originally, the UVP only measures one-dimensional velocity profile. For two-dimensional flow mapping, it is necessary to measure two velocity component at one spatial point to form a vector. In the present work, measurement system with two ultrasonic array sensors have been developed for two-dimensional velocity measurement and tested at two-phase bubbly column flow. The measurement results of UVP were compared with PIV measurement result to evaluate performance of the system. In two-phase bubbly flow, the performance of measurement system with ultrasonic array sensor is evaluated as 20% comparing with PIV measurement results for one and two-dimensional velocity measurement.