Measurement of Bubbly Two-phase Flow in Vertical Pipe Using Multiwave Ultrasonic Pulsed Dopller Method and Wire Mesh Tomography

Abstract Two measurement methods which are multiwave ultrasonic pulsed Doppler (multiwave UVP) method and wire mesh tomography (WMT) have been applied to the measurement of bubbly two-phase flow. Velocity profiles of bubbles and liquid have been measured using multiwave UVP. Simultaneously, cross-sectional void fraction distribution has been measured using WMT. As the result, a combination method has been set up. The measured parameters are indispensable in order to obtain detailed structures of two-phase flow. Multiwave UVP method exploits two basic ultrasonic frequencies which are 2 MHz and 8 MHz. Simultaneous measurement of velocity profiles of bubbles (using 2 MHz frequency) and those of liquid (using 8 MHz frequency), at the same position, is enabled. A multiwave ultrasonic transducer (multiwave TDX) which is able to emit and receive the two ultrasonic frequencies along the measurement line at the same time has been applied. The signal processing is based on the pulsed Doppler method. Using the combination method, first, instantaneous velocity profiles and void fraction distribution have been measured simultaneously for air-water counter-current bubbly flow in a vertical pipe. Flow structure has been clarified. Effect of initial condition on void fraction distribution has been confirmed. Next, measurements have been carried out for subcooled boiling bubbly flow in a vertical pipe. For measurement of subcooled boiling flow, a high temperature wire mesh sensor (WMS) has been developed. A method for separation of velocity profiles of bubbles with different sizes and velocities has been suggested.

[1]  M. Ishii,et al.  Axial interfacial area transport of vertical bubbly flows , 2001 .

[2]  Horst-Michael Prasser,et al.  Wire-mesh sensors for high-resolving two-phase flow studies at high pressures and temperatures , 2007 .

[3]  Hiroshige Kikura,et al.  Application of ultrasonic doppler method for bubbly flow measurement using two ultrasonic frequencies , 2005 .

[4]  Hiroshige Kikura,et al.  Tomographic imaging of counter-current bubbly flow by wire mesh tomography , 2007 .

[5]  H. Prasser,et al.  A new electrode-mesh tomograph for gas–liquid flows , 1998 .

[6]  N. Zuber,et al.  Average volumetric concentration in two-phase flow systems , 1965 .

[7]  Yasushi Takeda,et al.  Ultrasonic Doppler Velocity Profiler for Fluid Flow , 2012 .

[8]  Katsuji Yamaguchi,et al.  Characteristics of Countercurrent Gas-Liquid Two-Phase Flow in Vertical Tubes , 1982 .

[9]  F. J. Moody,et al.  The thermal hydraulics of a boiling water nuclear reactor , 1977 .

[10]  Yehuda Taitel,et al.  Counter current gas-liquid vertical flow, model for flow pattern and pressure drop , 1983 .

[11]  Yasushi Takeda,et al.  Velocity profile measurement by ultrasound Doppler shift method , 1986 .

[12]  Hiroshige Kikura,et al.  Application of ultrasonic multi-wave method for two-phase bubbly and slug flows , 2008 .

[13]  Sven Eckert,et al.  Velocity measurements at high temperatures by ultrasound Doppler velocimetry using an acoustic wave guide , 2003 .

[14]  Bernhard R. Tittmann,et al.  High temperature ultrasonic transducer up to 1000 °C using lithium niobate single crystal , 2010 .

[15]  N. Afgan.  Transient phenomena in multiphase flow , 1988 .

[16]  M. Aritomi,et al.  Intrusive Effect of Wire Mesh Tomography on Gas-liquid Flow Measurement , 2003 .

[17]  K. Yamaguchi,et al.  Combinated Flow Pattern Map for Cocurrent and Countercurrent Air-Water Flows in Vertical Tube , 1984 .

[18]  Ion Tiseanu,et al.  Comparison between wire-mesh sensor and ultra-fast X-ray tomograph for an air–water flow in a vertical pipe , 2005 .

[19]  Hiroshige Kikura,et al.  Micro wire-mesh sensor for two-phase flow measurement in a rectangular narrow channel , 2011 .