An experimental study on the effect of polymers on the sustaining mechanism of turbulent heat transfer in turbulent water duct flow

聚合物对湍流水管流中湍流传热维持机制影响的实验研究

基本信息

批准号：
11650222
负责人：
HAGIWARA Yoshimichi
金额：
$ 1.66万
依托单位：
Kyoto 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：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

We developed new techniques for simultaneous visualization of near-wall coherent structure, lumps of entangled polymers and thermal field in a turbulent water duct flow with an introduction of dilute polymer solution from a transverse slot into the buffer region. The main conclusions obtained are as follows.1.The fine particles of fluorescence color, the hydrogen bubbles, dye introduced into the viscous sublayer were found to be effective for the simultaneous visualization for the entangled polymers, the streamwise vortices, and the low-speed streaks, respectively.2.The green-color images contain reflected light from the bubbles, while the red-color images contain fluorescence from the color particles and the dye. Therefore, the motions of bubbles, color particles and dye can be measured independently.3.The eruptive flow induced by the streamwise vortices was measured by applying a PTV technique to the motion of bubbles. It was observed that the evolution of streamwise vortices, and thus the eruptive flow and the lift-up of low-speed streaks were attenuated by the polymer lumps.4.The planer laser-induced fluorescence(PLIF)technique is found to be promising for the measurement of thermal filed in the buffer layer.5.The combination of PLIF, the visualization method with color particles and hydrogen bubbles, and the image-capturing system with two cameras were found to be promising to the simultaneous observation of thermal field, the vortices and the entangled polymers.6.A decrease in the temperature at the buffer layer due to the flow induced by the streamwise vortices was measured. It was observed that the entangled polymers attenuated the generation and evolution of the vortices and thus the aforementioned temperature fluctuation.

我们开发了新技术，用于同时可视化近壁相干结构，纠缠聚合物的团块和湍流水管流中的热场，并从横向插槽中引入稀聚合物溶液进入缓冲液区域。获得的主要结论如下。1。发现荧光颜色的细颗粒，氢气，引入到粘性的子层中的染料可有效地有效地可视化，分别对纠缠聚合物，流向涡旋，分别从绿色图像中包含绿色图像，同时构成了绿色图像，同时又有绿色图像。2.。染料。因此，可以独立测量气泡，颜色颗粒和染料的运动。3。通过将PTV技术应用于气泡运动，通过将PTV技术应用于流向涡流诱导的喷发流动。据观察，流质涡流的演变，因此，聚合物块的爆发流和低速条纹的提升被衰减。发现摄像机可以同时观察热场，涡旋和纠缠聚合物。6.a由于测量了流向涡流引起的流动引起的缓冲层的温度降低。据观察，纠缠的聚合物减弱了涡旋的产生和演化，因此会衰减上述温度波动。