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Bubble behavior has a significant impact on the characteristics of two-phase flow and heat transfer. To investigate the dynamics of bubbles in a petal-shaped rod bundle channel, the behavior of bubbles in static water in the rod bundle channel was simulated using the volume of fluid method (VOF) and compared with the behavior of moving bubbles in a circular rod bundle channel. The trajectory, shape, and rise velocity of bubbles with different initial sizes were obtained and analyzed to understand the mechanism of bubble behavior through the flow and pressure fields around the bubbles. The results show that bubbles exhibit lateral movement during the ascent process. The smaller the bubble size, the more pronounced the lateral movement, making it more likely for the bubble to touch the wall surface. After touching the wall surface, the bubble slides along the wall surface. Bubbles that do not touch the wall move towards the center of the flow channel and finally rise steadily along the center. The calculated size range produces spherical and ellipsoidal bubble shapes. Before the bubble touches the wall, the bubble deformation increases and the aspect ratio decreases as the bubble gradually rises, reaching stability after a period of time. While after the bubble touches the wall, the bubble adheres to the wall and its shape changes to semi-circular and its aspect ratio decreases rapidly. The stabilization rate of bubble increases as the size of the bubble increases. In the first stage, the bubble velocity rises rapidly from zero and the wake begins to form. In the second stage, the bubble velocity rises slowly and the wake changes asymmetrically at both ends of the bubble. In the third stage, the bubble velocity decreases rapidly if it touches the wall, and the shape of the wake changes near the wall. If the bubble does not touch the wall, the bubble velocity will fluctuate around the stable velocity and the flow field will stabilize, and the wake will be generated and shed in a continuous cycle. The direction of bubble movement can be determined by the pressure distribution around the bubble. Compared to the circular rod channel, the bubbles in the petal-shaped fuel rod channel have a greater lateral displacement and are more likely to touch the wall, while the bubble shape is less variable. The study of bubble upward motion can clarify the bubble behaviour in the petal-shaped rod bundle channel and provide a basis for revealing the two-phase flow and heat transfer mechanism.

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Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the effect of anistropic properties of composite material on bubble shape, the shapes of bubbles near the carbon fiber composite material boundaries and the deformation of the carbon fiber composite material boundaries were recorded and observed by using high-speed camera. The shapes of bubbles near the composite material boundaries with different ply angles are studied. The changing processes of bubble shape and the deformation modes of the composite material boundaries at the same initial distance of bubble from the boundary are compared for the carbon fiber composite plates with the ply angles of 0°,90° and 0°+90°. The results show that the high-speed jet and shock wave generated by the collapse of bubble near the boundaries are the important factors for the damage of boundaries, and the different ply angles of carbon fiber composite material lead to different deformation modes, which has an important impact on the shapes of bubbles. [ABSTRACT FROM AUTHOR]

The bubble growth and detachment was recorded using a high speed video technology. The post-processing of photos was completed by Image-Pro Plus 6.0 software. The bubble shape variation during bubble growth under the condition of two kinds of different tube diameters was investigated. The experimental results show that the dominant force during bubble growth is different for different diameter tube. The increment of bubble aspect ratio from the small diameter tube with time is greater at first and then becomes smaller， while that from the large diameter one with time is firstly smaller and then greater afterward. Since the bubble detachment condition cannot be satisfied for the small diameter tube， the bubble bottom edge migrates towards liquid side. On the other hand， the bubble detachment condition can be reached for the large tube when the angle between gas-liquid line and solid-liquid line is smaller than the contact angle， therefore the bubble bottom edge cannot migrate towards liquid side. The critical bubble aspect ratio for detachment of 3.80mm bubble is slightly larger than that of 9.28mm bubble. [ABSTRACT FROM AUTHOR]