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Murai, Yuichi*; Yoshikawa, Shinji; Toda, Shinichi*; Ishikawa, Masaaki*; Yamamoto, Fujio*
Nuclear Engineering and Design, 236(1), p.94 - 106, 2006/01
Times Cited Count：65 Percentile：96.69(Nuclear Science & Technology)Air-water two-phase flow in helicallly coiled tube of 20mm in the internal diameter is investigated ezperimentally to elucidate the effect of centrifugal acceleration on the flow regime map and the local instantaneous flow structure. Three kinds of test tubes including a straight tube are used to compare the flow structure under turbulent flow condition. The superficial velocity up to 6 m/s is tested so that centrifugal Froude number covers a range from 0 to 3. The inter facial structure is visualized from two directions by a high-speed video system with a synchronized measurement of local pressure fluctuation. The results reveral that the flow transition line alters due to centrifugal force acting on liquid phase in the tube. Especially the bubbly fow regime is narrwed significantly. The pressure fluctuation amplitude gets large relatively to the average presure loww as void fraction increases. The Frequency spectra of the pressure fluctuation have plural peaks in the case of strong curvature, implying that the periodicity of slugging two-phase flow is collapsed by internal secondary flow actibated inside liquid phase. Moreover, the substantial velocity of gas phase is slower than the total superficial velocity in case of large Froude number because of biased distribution to the inner surface allowing liquid flow passing outside as like a radial stratified flow.
Murai, Yuichi*; Oiwa, Hiroshi; Sasaki, Toshio*; Kondo, Masahiko; Yoshikawa, Shinji; Yamamoto, Fujio*
Measurement Science and Technology, 16(7), p.1459 - 1468, 2005/07
Times Cited Count：31 Percentile：81.38(Engineering, Multidisciplinary)Air-water two-phase flow in a helically coiled tube is investigated using backlight imaging tomography to elucidate the effect of centrifugal acceleration on phase distribution and interfacial structure. Superficial velocities up to 6m/s in 20mm-diameter tube are tested. We focused on a slug flow regime in which centrifugal acceleration dominates the flow. The interfacial structure is visualized in six directions using a set of originally designed mirror-mounted water jackets. A temporal expansion image is made from line-sampled images, and is used to reconstruct phase distribution through a linear backward projection algorithm. The present topography measurement showed various new features of gas-liquid two-phase flow in a helically coiled tube, such as a wall-covering effect in the case of high superficial velocity.
Oiwa, Hiroshi; Murai, Yuichi*; Sasaki, Toshio*; Yoshikawa, Shinji; Yamamoto, Fujio*
Proceedings of 4th World Congress on Industrial Process Tomography, Vol.1, p.428 - 433, 2005/00
We carried out reflection seismic and multi-offset VSP surveys at JNC Shobasama-site to develop the investigation technique in the granite area, and evaluated the applicability of these geophysical methods. As the result of this study, we consider that a) It is possible to infer the existence of the lower angle fracture zone in the granite by eflection seismic survey and b) Multi-offset VSP supplements the result of reflection seismic survey and it is possible to infer the distribution of the fracture zone in deeper area in the granite.
Murai, Yuichi*; Yamamoto, Fujio*; Ishikawa, Masaaki*; Sakai, Kosuke*; Oiwa, Hiroshi*; Toda, Shinichi; Yoshikawa, Shinji; Tamayama, Kiyoshi
JNC TY4400 2003-006, 75 Pages, 2003/06
JNC-TY4400-2003-006.pdf:12.95MB
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