抄録
Development of ultrasonic velocity profile (UVP) method for two-phase flow using spike signals is executed. Multiwave transducer (TDX) which can emit two different ultrasonic frequencies, i.e. 2MHz and 8MHz for liquid/bubble two-phase flow, has been developed. The spike signal is frequently used for ultrasonic inspection as non-destructive test discipline, and it has less number of waves and time to pass than conventionally used burst signals. A pulser/receiver (P/R) for spike and a flexible unit as the analog to digital converter (ADC) are applied to this system. The measurement method which is based on ultrasonic Doppler method (UDM) and autocorrelation method based on Wiener-Khinchine's theorem is applied instead of conventional FFT based technique. Multiwave method has been developed for the measurement of two-phase bubbly flows. Furthermore, a phase separation method has been proposed, which leads to obtain instantaneous velocity profiles of both liquid and bubble. Practical application of the new method has been conducted, and the results show the robustness of the method. In addition, the instantaneous local void fraction profiles can be calculated along the measurement line using this method. Further investigation of two-phase flows in a vertical pipe with varied flow configurations will be conducted.
