Flow Visualization in Wind Tunnels
Flow Visualization in Wind Tunnels
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DOI：
10.5772/21494
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发表时间：
2011-07
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通讯作者：
M. Mahmood
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文献类型：
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作者：
M. Mahmood
流动可视化是一种检测物体周围或表面流动模式的实验手段。通过将染料、烟雾或颜料引入被调查区域的水流中，可以使水流“可视化”。这种方法的主要优点是它能够在没有复杂的数据简化和分析的情况下提供对模型的流的描述。烟流可视化（由Bradshaw（1970年）和Rae和Pope（1984年）描述）涉及将蒸汽流注入流中。蒸汽沿着细丝线（由所有通过注射点的流体粒子组成的线）在稳定流动中，细丝线与流线相同。（与速度矢量相切的直线）。因此，烟流可视化显示了物体周围的整个流动模式。流可视化的价值怎么夸大都不为过。在模型上看到流动模式的能力通常会给空气动力学问题的解决方案提供洞察力。流动可视化可分为两大类：第一类是表面流动可视化，将可视化介质应用于表面，如簇丛、油流等。第二种类型是远离表面的，如烟雾和溪流。基本上有四种记录流动可视化测试的方法。对于科学家和工程师来说，第一个也是最好的，但也是最不持久的方法是用眼睛观察。由于深度知觉，人们可以看到三维的画面。另外三种记录流可视化结果的常用方法是通过胶片，无论是静止的还是电影或电视摄像机或录像带和磁带。必须认识到，这三种方法都是使用二维介质来记录三维现象。当使用烟雾或氦气泡来追踪流经模型的流线时，这一点尤其好。这三种方法都可以使用黑白或彩色。与视频相比，摄影方法虽然记录了更多的时间来冲洗和打印静止图像，但却产生了更高的分辨率。
Flow visualization is an experimental means of examining the flow patterns around a body or over its surface. The flow is “visualized” by introducing dye, smoke or pigment into the flow in the area under investigation. The primary advantage of such a method is its ability to provide a description of the flow over a model without a complicated data reduction and analysis. Smokeflow visualization (described by Bradshaw, 1970 and Rae and Pope 1984) involves the injection of streams of vapor into the flow. The vapor follows filament lines (lines made up of all the fluid particles passing through the injection points) in steady flow the filament lines are identical to stream lines. (Lines everywhere tangent to the velocity vector). Smokeflow visualization thus reveals the entire flow pattern around a body. It is difficult to exaggerate the value of flow visualization. The ability to see flow pattern on a model often gives insight into a solution to an aerodynamic problem. Flow visualization can be divided into two broad categories the first is surface flow visualization when the visualization media is applied to the surface such as tufts and oil flow etc. The second type is off surface such as smoke and streams. There are basically four methods of recording the flow visualization test. The first and the best but the least permanent method is for the scientist and the engineer to observe with his eyes. Because of the depth perception one can see a three dimensional picture. The other three common methods of recording the result of flow visualization are by film, either still or movie or television camera or video and magnetic tapes. It must be realized that all three of these methods are using a two dimensional medium to often record a three dimensional phenomena. This is especially fine when using a smoke or helium bubbles to trace flow stream lines pass the model. All three of these methods can be used either black and white or color. The photography methods while recording more time for developing and printing stills, when compared to video, yield higher resolution.