Three-dimensional liquid film flow measurement based on digital image projection technology
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摘要: 流体薄膜流动定量测量是分析结冰相变传热过程的必要手段。基于图像处理的数字图像投影技术(DIP)可实现对流体薄膜的非侵入式定量测量。对DIP技术的基本原理、图像互相关算法和标定方法进行了介绍,设计并搭建了DIP测量系统和平板水膜流动实验台。DIP测量系统的整体误差在5%以内,证明了系统的可靠性与准确性。在平板水膜流动实验台上开展了一系列水膜流动实验,采用DIP测量系统复原了平板水膜流动的三维全貌。通过测量结果拟合得出平均水膜高度、无量纲水膜高度与水膜雷诺数之间的关系,并与理论推导和文献实验结果进行对比,整体趋势一致。Abstract: Quantitative measurement of fluid film flow is a necessary means to analyze the heat transfer process of the icing phase change. Digital Image Projection (DIP) based on image processing enables non-invasive quantitative measurement of fluid films. Firstly, the basic principles, cross-correlation algorithm and calibration method of the DIP technology are introduced. Based on this, the DIP system and the flat water film flow test bench are designed and built. Subsequently, the overall error of the DIP system was tested and was found to be within 5%, indicating the reliability and accuracy of the system. A series of water film flow experiments were carried out on a flat water film flow test bench. The DIP system was used to restore the three-dimensional full picture of the flat water film flow. Finally, the relationship between the average water film thickness as well as the dimensionless water film thickness and the water film Reynolds number is obtained by fitting the measurement results, and is compared with the theoretical derivation and literature experimental results. Results show the overall trend is consistent.
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表 1 无量纲水膜厚度模型
Table 1. Dimensionless Film Thickness Models
Author Applied Ref Relation Kosky & Staub[21] Horizontal
condense flow13.0~370.0 $h^{+}=1.316\,0 \ { {Re} }_{ {\rm{f} } }^{0.529\,9}$ Rishikesan[4] Plate flow 26.0~128.0 $\,\, h^{+}=1.292\,0 \ {{Re} }_{ {\rm{f} } }^{0.528\,9}$ Hughmark[22] Upward flow 25.0~250.0 $h^{+}=0.874\,0 \ { {Re} }_{ {\rm{f} } }^{2 / 3}$ Present work Plate flow 16.0~190.0 $h^{+}=1.397\,3\ {{Re} }_{ {\rm{f} } }^{0.568\,9}$ -
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