Improrement of PIV Measurement Accuracy and Identification of Structures for Turbulent Flows

PIV测量精度的提高和湍流结构的识别

• 批准号: 14550178
• 负责人: TSUJI Toshihiro
• 金额: $ 2.18万
• 依托单位: Nagoya Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550178/
• 关键词: Turbulent buoyant flow; Natural convection; Mixed convection; PIV measurement; Measurement Uncertainty; Turbulent boundary layer; Turbulence structure; Turbulence model

A turbulent natural-convection boundary layer induced along a vertical heated surface made of a 1 m wide and 4 m high copper plate was measured with a particle image velocimetry (PIV). The boundary layer flow was seeded with smoke and illuminated by light sheets discharged from a double pulse Nd : YAG laser system. Time-series video images captured by a CCD camera for several minutes were directly recorded with a mass-storage device purchased by Grant-in AID for Scientific Research, and instantaneous velocity vectors and turbulence statistics were calculated with a cross-correlation method and a sub-pixel algorism. In consequence, it is founded that turbulent statistics with the PIV were approximately consistent with those obtained with a hot-and cold-wires due to the acquirement of adequate time-series data, which had not been realized without a mass-storage device. However, incorrect velocity vectors were observed and frequency appearance of the incorrect vectors increased in the int … More ermittent outer region of the boundary layer, and thus the advanced improvement of measurement accuracy was required.In addition to the actual visualization measurement, database of visualized images were established with a direct numerical simulation (DNS) for a time-developing turbulent boundary layer on a flat plat to confirm the accuracy of PIV measurement. Benchmark images were created by looking upon the concentration distribution derived from the simulation as the luminance distribution of seeded particles, and were processed to calculate velocity vectors. Then, the calculated vectors ware compared with those obtained directly from the DNS and the uncertainty of PIV measurement was accessed for the effects of laser-sheet width, pulse injection interval and image processing algorism. As the result of such comparisons, it is ascertained for the three-dimensional turbulent behavior in the natural-convection boundary later that incorrect velocity vectors certainly apt to appear intermittent region, the laser-sheet width has no effect on the calculated velocity vectors, the optimum pulse injection interval was 3-4 seconds and the size of interrogation windows should be relatively enlarged to calculate accurate velocity vectors with a cross-correlation method. These results will be submitted to the international journal concerning flow measurement and visualization in the near term. Less

用粒子图像测速仪（PIV）测量了沿着宽1 m、高4 m的垂直加热表面上的自然对流湍流边界层。边界层流动被播种与烟雾和照明的光片从双脉冲Nd：YAG激光系统放电。利用美国科学研究资助计划（Grant-in AID for Scientific Research）购买的大容量存储设备直接记录CCD摄像机拍摄的几分钟时间序列视频图像，采用互相关法和亚像素算法计算瞬时速度矢量和湍流统计量。结果表明，PIV测量的湍流统计数据与用热线和冷线测量的结果基本一致，这是因为PIV测量获得了足够的时间序列数据，而这在没有大容量存储设备的情况下是无法实现的。然而，在实验中观察到了错误的速度矢量，并且错误的速度矢量出现的频率增加 ...更多信息 为了进一步提高PIV测量的精度，在实际可视化测量的基础上，采用直接数值模拟（DNS）方法对平板上随时间发展的湍流边界层进行可视化图像数据库的建立。通过将从模拟得到的浓度分布视为接种颗粒的亮度分布来创建基准图像，并对其进行处理以计算速度矢量。然后将计算得到的矢量与直接从DNS得到的矢量进行比较，并对激光片宽、脉冲注入间隔和图像处理算法对PIV测量的不确定度进行了评定。结果表明，对于以后自然对流边界的三维湍流行为，不正确的速度矢量必然会出现间断区，激光片宽度对计算的速度矢量没有影响，最佳脉冲注射间隔为3-4秒，询问窗口的大小应相对增大，以便用互相关方法计算准确的速度矢量。这些结果将在近期内提交给有关流动测量和可视化的国际期刊。少

项目成果

T.Kajitani, H.Kaga, T.Tsuji: "Heat transfer enhancement in a turbulent natural convection boundary layer and PIV measurement"Proceedings of Tokai Branch (Mie Block) Lecture Meeting(Japan Society of Mechanical Engineers). 033-2. 60-61 (2003)

T.Kajitani、H.Kaga、T.Tsuji：“湍流自然对流边界层中的传热强化和 PIV 测量”东海分会（三重区）演讲会论文集（日本机械工程学会）。

H.Taufan, H.kubo, T.Tsuji: "Analysis of time-developing turbulent boundary layer on a flat plate"Proceedings of Thermal Engineering Conference '2(Japan Society of Mechanical Engineers). 02-22. 13-14 (2002)

H.Taufan、H.kubo、T.Tsuji：“平板上随时间发展的湍流边界层的分析”热工会议论文集2（日本机械工程师学会）。

T.Kajitani, T.Tsuji, M.Katsuki, Y.Hattori: "PIV measurement of turbulence characteristics in natural convection boundary layer and its accuracy"Proceedings of Annual Meeting 2004 (Japan Society of Mechanical Engineers). (to be presented). (2004)

T.Kajitani、T.Tsuji、M.Katsuki、Y.Hattori：“自然对流边界层湍流特性的 PIV 测量及其精度”2004 年年会论文集（日本机械工程师学会）。

HendriTaufan, 久保英士, 辻俊 博: "時間発展平板乱流境界層の解析"日本機械学会熱工学講演会講演諭文集. No.02-22. 13-14 (2002)

HendriTaufan、Hideshi Kubo 和 Toshihiro Tsuji：“时间演化平板湍流边界层的分析”日本机械工程师学会热工会议论文集第 02-22 号（2002 年）。

梶谷 剛, 加賀博之, 辻 俊博: "自然対流乱流境界層の伝熱促進とPIV計測"日本機械学会東海支部三重地方講演会講演諭文集. (発表予定). (2003)

Tsuyoshi Kajitani、Hiroyuki Kaga、Toshihiro Tsuji：“自然对流湍流边界层中的传热增强和 PIV 测量”日本机械工程师学会东海分会三重地区讲座会议记录（待发表）。