Measurement of clustering flow by high resolution laser sheet technique and mathematical model development for large scale circulating fluidized beds.

高分辨率激光片技术测量团簇流和大型循环流化床数学模型开发。

• 批准号: 06555226
• 负责人: HORIO Masayuki
• 金额: $ 11.65万
• 依托单位: TOKYO UNIVERSITY OF AGRICULTURE AND TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research (B)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06555226/
• 关键词: Circulating Fluidized Bed; Laser Sheet Technique; Flow Visualization; Gas-Solid Suspension; High speed video recording; particle cluster; 3 dimensional visualization; image processing; 固気混相流

Measurement of clustering flow by high resolution laser sheet technique in a large scale circulating fluidized bed and numerical model developmentThe macroscopic flow structure of circulating fluidized beds including overall slip velocity and dense region voidage are closely related to meso-scale and microscale flow structures. From such a point of view, we have been studying the various aspect of cluster behavior in gas solid suspension structure. However, the three dimensional meso-scale structure of clustering suspensions has not been clarified yet.In this work the three dimensional flow structure of dilute gas solid suspensions in a circulating fluidized bed cold model (200mm riser diameter) was visualized by the scanning laser sheet technique. To compose the three dimensional image of gas solid suspensions the scanning laser sheet images were treated with a computer image processing technique, in particular, modification of weakened images of objects by reduced laser sheet illumin … More ation, two-level quantization, detection of boundary line and conneciton of images to obtain three dimensional surfaces. Shapes of clusters and gas channels were observed in detail. Clusters of roughly several centimeters still exist in the dilute suspension. In addition to the large gas channels, a complicated network of dilute and cluster phases was observed. From the images of horizontal cross sections at different height big gas drafts were seen around clusters and small channel exist in clusters.To quantify the shape change the fractal analysis was applied to the 3-D images of solid concentration.The clustering suspension has the fractal structure at any conditions tested. With the decrease in gas velocity and increase in solid circulation flux, fractal dimension increased indicating the formation of more complex 2 or 3 dimensional structures.A simple model is presented to predict the cluster size and the cluster voidage for a given set of operating conditions and suspension voidage. In this model a cluster is supposed to be suspended by both gas flows inside and outside the cluster, and the gas around the cluster is supposed to form bubble like gas pockets moving upward. Model predictions were successfully compared with the experimental data in the literature. Less

大尺度循环流化床内团簇流动的高分辨率激光片光测量及数值模型的建立循环流化床内宏观流动结构（包括整体滑移速度和密相区空隙率）与细观和微观流动结构密切相关。从这一观点出发，我们研究了气固悬浮结构中团簇行为的各个方面。本文采用激光片层扫描技术，对循环流化床冷态模型（直径200mm）中稀相气固悬浮体系的三维流动结构进行了可视化研究。为了合成气固悬浮物的三维图象，用计算机图象处理技术对激光扫描片象进行处理，特别是用减少的激光片照明来修正物体的弱化图象。 ...更多信息 图像的分割、两级量化、边界线检测和拼接得到三维表面。详细观察了团簇的排列和气体通道。大约几厘米的团簇仍然存在于稀释的悬浮液中。除了大的气体通道，一个复杂的网络的稀相和集群观察。从不同高度的水平截面图像可以看出，颗粒团周围存在大的气流，颗粒团内部存在小的通道，为了定量描述颗粒团的形状变化，对颗粒团的三维浓度图像进行了分形分析，颗粒团悬浮液在任何实验条件下都具有分形结构。随着气速的降低和固体循环流量的增加，颗粒团簇的分形维数增加，表明颗粒团簇形成了更为复杂的二维或三维结构。在该模型中，团簇被团簇内外的气流悬浮，团簇周围的气体形成气泡状的气袋向上运动。模型预测成功地与文献中的实验数据进行了比较。少

项目成果

M.Horio et al.: ""Three dimensional visualization of gas solid suspension flow if circulating fluidized beds" Proceedings of 1st International Particle Technology Forum. vol.1. 428-433 (1994)

M.Horio 等人：“循环流化床气固悬浮液流动的三维可视化”第一届国际粒子技术论坛论文集。第 1 卷。428-433 (1994)

M.Horio,et al.: "Three dimensional visualization of gas solid suspension flow in circulating fluidized beds" Proceedings of 1st International Particle Technology Forum,AICHE. 1. 428-433 (1994)

M.Horio等人：“循环流化床中气固悬浮液流动的三维可视化”第一届国际粒子技术论坛论文集，AICHE。

M.Horio and M.Ito: "Prediction of Cluster Size in Circnlating Fluidized Beds" The 5th International Conference on Circulating Fluidized Bed. 発表予定. (1996)

M.Horio 和 M.Ito：“循环流化床中簇尺寸的预测”第五届循环流化床国际会议（1996 年）。

M.Horio: "Three dimensional visualization of gas solid suspension flow in circulating fluidized beds" Preprints of 1st International Particle Technology Forum,AIChE. 1. 428-433 (1994)

M.Horio：“循环流化床中气固悬浮液流动的三维可视化”第一届国际粒子技术论坛预印本，AIChE。

M. Horio. et al.: "Three dimensional visualization of gas solid suspension flow in circulating fluidized beds." Proceedings of 1st International Particle Technology Forum. AICIE. 1. 428-433 (1994)

M.堀尾。