A simultaneous planar laser-induced fluorescence, particle image velocimetry and particle tracking velocimetry technique for the investigation of thin liquid-film flows
A simultaneous planar laser-induced fluorescence, particle image velocimetry and particle tracking velocimetry technique for the investigation of thin liquid-film flows
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DOI：
10.1016/j.expthermflusci.2015.06.008
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发表时间：
2015-11-01
影响因子：
3.2
通讯作者：
Markides, Christos N.
中科院分区：
文献类型：
--
作者：
Charogiannis, Alexandros;An, Jae Sik;Markides, Christos N.
描述了一种基于平面激光诱导荧光成像（PLIF）和粒子图像/跟踪测速（PIV/PTV）的同步测量技术，用于研究谐波激发液体薄膜流的流体动力学特性。该技术是广泛实验活动的一部分，涵盖四种不同的卡皮查 (Ka) 数液体、范围为 2.3-320 的雷诺 (Re) 数以及范围为 1-10 Hz 的入口强迫/波频率。将平坦（粘性和非受力）薄膜的薄膜厚度（来自 PLIF）与微米级测量和分析预测（努塞尔解）进行比较，所得平均偏差低于成像装置的标称分辨率（约 20 μm）。计算 PTV 得出的界面速度和整体速度与分析结果之间的相对偏差，两个测试案例的平均值不超过 3.2%。此外，将使用 LIF/PTV（膜厚度和速度分布）数据恢复的流量与直接流量计读数进行比较。总共六个平坦流和九个波浪流的平均相对偏差为 1.6%。还实现了波/锁相流场平均的实践，允许沿着波拓扑生成高度局部化的速度剖面、总体速度和流量数据。基于这些数据，从沿波拓扑的 20 个位置提取速度剖面，并与基于局部膜厚度测量和努塞尔特解的分析得出的速度剖面进行比较。发现通过调制强迫频率来增加波纹度会导致波峰之前的实验与理论预测之间的绝对偏差较低，而波峰之后的偏差较高。在波峰处，实验得出的界面速度被高估了近 100%。最后，在波峰之前识别出局部非抛物线速度剖面；一种可能与横流速度场相关的现象。 (C) 2015 年作者。由 Elsevier Inc. 出版。这是一篇基于 CC BY 许可证 (http://creativecommons.org/licenses/by/4.0/) 的开放获取文章。
A simultaneous measurement technique based on planar laser-induced fluorescence imaging (PLIF) and particle image/tracking velocimetry (PIV/PTV) is described for the investigation of the hydrodynamic characteristics of harmonically excited liquid thin-film flows. The technique is applied as part of an extensive experimental campaign that covers four different Kapitza (Ka) number liquids, Reynolds (Re) numbers spanning the range 2.3-320, and inlet-forced/wave frequencies in the range 1-10 Hz. Film thicknesses (from PLIF) for flat (viscous and unforced) films are compared to micrometer stage measurements and analytical predictions (Nusselt solution), with a resulting mean deviation being lower than the nominal resolution of the imaging setup (around 20 mu m). Relative deviations are calculated between PTV-derived interfacial and bulk velocities and analytical results, with mean values amounting to no more than 3.2% for both test cases. In addition, flow rates recovered using LIF/PTV (film thickness and velocity profile) data are compared to direct flowmeter readings. The mean relative deviation is found to be 1.6% for a total of six flat and nine wavy flows. The practice of wave/phase-locked flow-field averaging is also implemented, allowing the generation of highly localized velocity profile, bulk velocity and flow rate data along the wave topology. Based on this data, velocity profiles are extracted from 20 locations along the wave topology and compared to analytically derived ones based on local film thickness measurements and the Nusselt solution. Increasing the waviness by modulating the forcing frequency is found to result in lower absolute deviations between experiments and theoretical predictions ahead of the wave crests, and higher deviations behind the wave crests. At the wave crests, experimentally derived interfacial velocities are overestimated by nearly 100%. Finally, locally non-parabolic velocity profiles are identified ahead of the wave crests; a phenomenon potentially linked to the cross-stream velocity field. (C) 2015 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).