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Hydrodynamic force acting on the structures, pipes and various forms of objects can generate destructive vibrations, and could cause acoustic and noise problems in industrial machineries. Such phenomenon is known as Flow-Induced Vibration (FIV), and it can obstruct smooth operation of engineering devices and could potentially cause serious consequences like system failures. The subject has become increasingly important problem in engineering industry in recent years for both single-phase and multi-phase flow cases, as well as for various flow orientations including external and internal flows. Present review paper summarizes the historical background of FIV research and how the phenomenon has been classified in both industrial and academic fields, particularly focusing on the progress of two-phase FIV research. Special attention was paid to the subject of internal two-phase FIV generated at industrial piping systems two-phase flow regimes. Based on the extensive and comprehensive literature survey, most up-to-date progress of the research in the area of two-phase flow induced vibration in piping system are thoroughly reviewed and presented in this article. [ABSTRACT FROM AUTHOR]

Several researchers have reported the detachment of vapor bubbles from a vertical heated wall in upward flow boiling of water. In these experiments, the bubble shape was frequently flattened along the wall at inception but became more rounded before the onset of detachment. In this study, the motion of two-dimensional bubbles is investigated numerically to elucidate the mechanism of bubble detachment. The numerical results show that the change in bubble shape due to surface tension force induces the liquid flow from the periphery to the base of bubble and consequently the liquid inertia lifts the bubble from the wall. [ABSTRACT FROM AUTHOR]

Abstract: Axial developments of the local void fraction, interfacial area concentration and bubble Sauter mean diameter were measured in subcooled boiling flow of water in a vertical internally heated annulus using the double-sensor conductivity probe technique. Measurements were performed under varying conditions of heat flux, inlet liquid velocity and inlet liquid temperature. A total of 10 data sets were acquired. Based on these measurements with the previous data obtained in the present test loop, the influence of flow condition on the profiles of local two-phase flow parameters was discussed. The measured average void fraction and interfacial area concentration were compared with the predictions by existing correlations for drift-flux parameters and interfacial area concentration. Also, the recently proposed bubble layer thickness model in subcooled boiling was evaluated for the measurement data. [Copyright &y& Elsevier]

Abstract: For the purpose of accurate flow measurement, an automatic three-dimensional (3D) sound field measurement system has been developed, and an experimental study has been conducted on ultrasonic properties. By using this system, ultrasonic sound pressure distributions and radiation angles in water have been measured. According to Snell’s law, the ultrasonic transmission properties can be obtained on the basis of incidence angle, acoustic impedance, basic frequency of ultrasound, and material and thickness of the metallic plate. However, this law cannot be applied to certain cases where an ultrasonic incident wave passes through a metallic plate and turns into a longitudinal wave, a shear wave and a Lamb wave. Consequently, the ultrasonic propagation paths have been investigated experimentally at various angles of incidence. From the experiments, it was confirmed that the ultrasonic beam paths change with incidence angles. Hence, the most suitable incidence angle has been determined from the result of measurements. Velocity measurements using an ultrasonic velocity profiler were made at various incidence angles. The accuracy of measuring flow rates changed with the incidence angles. The optimal incidence angle determined from 3D field measurements was found to yield the most accurate flow rates. [Copyright &y& Elsevier]