Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
An ultrasonic multi-wave sensor with more than two oscillators can measure the velocity profiles of both gas and liquid phase in bubbly flow by separating the reflected echo signals. In this study, two types of multi-waves sensors are used to measure air-water bubbly flow. The piezoelectric elements of a sensor have basic frequencies of 8 MHz for liquid phase and 2 MHz for gas phase, separately. On the other hand, another sensor has 8 MHz elements in the transmitting face. These sensors have cylindrical shape. At first, to apply these sensors to flow measurement, the transmitted sound pressure fields were investigated by experimental and numerical approaches. Then, the echo signals reflected from air-water bubbly flow in a vertical rectangular channel were measured by using these multi-wave sensors, and the flow structures were estimated from statistical analysis of echo signals and ultrasonic velocity profiling method.