Name: experimental investigation of the flow structure over a delta wing via flow visualization methods
Uploaded: 2018-04-23T15:00:00
Description: Watch this Scientific Journal Video about Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods at JoVE.com

作者谨此致谢香港研究资助局 (否。GRF526913), 香港创新科技委员会 (不。ITS/334/15FP), 美国海军研究局全球办事处 (不。N00014-16-1-2161) 提供财政支持。

1. 风洞设置
<ol><li>三角洲机翼模型
	<ol>
<li>构造一个三角翼模型从铝, 以扫角φ 75°, 弦长度c 280 毫米, 根跨度b 150 毫米和厚度5毫米。在35°上有两个前导边斜面以修复分离点17 (请参见图 1a)。</li>
	</ol></li>
	<li>风洞设施
	<ol>
<li>在闭环低速风洞中进行实验, 测试部分为2.4 米 (长度) x 0.6 米 (宽) x 0.6 米 (高度), 装有玻?...

<ol>
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本文介绍了两种流动可视化方法, 改进了烟气流动可视化和 PIV 测量, 对三角洲机翼的流动结构进行了定性和定量的研究。对实验的一般程序进行了逐步的描述。这两种方法的设置几乎相同, 而所涉及的设备则不同。这两种流动可视化方法的基本原理是通过激光片来照亮流动中的粒子。改进后的烟气流动可视化可以同时获得全局流结构和小局部结构, 有助于获得未知流结构的概述。定量 PIV 分析提供?...

通过可视化技术进行流场测量是流体工程的基本方法。在不同的可视化技术中, 风洞实验中的烟线流动可视化和水隧道实验中的染料可视化, 是对渗流结构进行定性描述的最广泛的应用。PIV 和激光多普勒测速技术 (LDA) 是两种典型的定量技术 1.
在烟雾线流动可视化中, 烟雾 streaklines 是由加热导线上的油滴产生的, 或在实验过程中从外层烟雾发生器/容器中注入。大功率灯或激光片用于照亮烟雾 streaklines。然后记录图像以进行进一步分析。这是一个简单但非常有用的流可视化方法2。然而, 这种方法的有效性可能受到各种因素的限制, 如烟线的短时间, 复杂的三维流场, 相对较高的流速和烟雾产生的效率3。
在 PIV 测量中, 带有气流粒子的流场的剖面由激光片照亮, 在这个剖面中粒子的瞬时位置被高速相机捕获。在极小的时间间隔内, 记录一对图像。通过将图像分割成一个审讯区网格, 通过交叉相关函数计算审讯区域内粒子的平均运动, 可以得到观测到的剖面上的瞬时速度矢量图。然而, 也知道, 必须达成妥协的因素, 包括观察窗口的大小, 速度图的分辨率, 平面的速度大小, 对图像的时间间隔, 正交速度大小和粒子密度4。因此, 可能需要进行许多探索性实验以优化实验设置。用 PIV 测量单独的5、6来调查未知和复杂的流场将是昂贵且耗时的。针对上述问题, 提出了一种结合烟气流动可视化和 PIV 测量的策略, 并在此基础上对细长三角洲机翼上的复杂流动进行了研究。
在三角洲机翼上进行的比对列的大量研究已经进行了7、8, 并使用流可视化技术作为主要工具。许多有趣的流现象被观察到: 螺旋型和气泡式涡击穿9,10, 不稳定剪切层子结构11,12, 列弗击穿位置的振荡13, 以及俯仰和偏航角度14、15、16在流结构上的影响。然而, 三角洲翼流中某些不稳定现象的基本机制仍然不清楚7。在这项工作中, 烟雾流动可视化的改进使用相同的播种粒子用于 PIV 测量, 而不是烟雾线。这种改进大大简化了可视化的操作, 提高了图像的质量。基于改进的烟气流动可视化结果, PIV 测量主要集中在感兴趣的流场上获取定量信息。
本文详细介绍了如何在风洞中进行流动可视化实验, 并研究了三角洲机翼上的非恒定流现象。本实验将两种可视化方法、改进的烟气流动可视化和 PIV 测量相结合使用。该过程包括设备设置和参数调整的分步指导。典型的结果表明, 结合这两种方法来测量复杂的流场的空间和世俗的优势。

<table>
	<tbody>
		<tr>
			<td>532 nm Nd:YAG laser</td>
			<td>Quantel Laser</td>
			<td>Evergreen 600mJ</td>
			<td></td>
		</tr>
		<tr>
			<td>High speed camera</td>
			<td>Dantec Dynamic</td>
			<td>HiSense 4M</td>
			<td></td>
		</tr>
		<tr>
			<td>camera lens</td>
			<td>Tamron</td>
			<td>SP AF180mm F/3.5 Di</td>
			<td></td>
		</tr>
		<tr>
			<td>PIV recording and processing software</td>
			<td>Dantec Dynamic</td>
			<td>DynamicStudio</td>
			<td></td>
		</tr>
		<tr>
			<td>cylindrical lens</td>
			<td>Newport</td>
			<td></td>
			<td>&#934;=12 mm</td>
		</tr>
		<tr>
			<td>convex lens</td>
			<td>Newport</td>
			<td></td>
			<td>f=700 mm</td>
		</tr>
		<tr>
			<td>neutral density filter</td>
			<td>Newport</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Calibration target</td>
			<td></td>
			<td></td>
			<td>custom made</td>
		</tr>
		<tr>
			<td>aerosol generator</td>
			<td>TSI</td>
			<td>TSI 9307-6</td>
			<td></td>
		</tr>
		<tr>
			<td>PULSE GENERATOR</td>
			<td>Berkeley Nucleonics Corp</td>
			<td>BNC 575</td>
			<td></td>
		</tr>
		<tr>
			<td>continuous laser</td>
			<td></td>
			<td>APGL-FN-532-1W</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital camera</td>
			<td>Nikon</td>
			<td>Nikon D5200</td>
			<td></td>
		</tr>
		<tr>
			<td>Image processing</td>
			<td>Matlab</td>
			<td></td>
			<td>custom code</td>
		</tr>
		<tr>
			<td>wind tunnel support</td>
			<td></td>
			<td></td>
			<td>custom made</td>
		</tr>
		<tr>
			<td>laser level</td>
			<td>BOSCH</td>
			<td>GLL3-15X</td>
			<td></td>
		</tr>
		<tr>
			<td>angle meter</td>
			<td>BOSCH</td>
			<td>GAM220</td>
			<td></td>
		</tr>
	</tbody>
</table>

experimental investigation of the flow structure over a delta wing via flow visualization methods

众所周知, 三角洲机翼上的流场由一对反旋转前缘涡 (列列) 控制。然而, 他们的机制还没有得到很好的理解。流场可视化技术是一种很有前途的非侵入性方法, 可以在空间和世俗上说明复杂的流动。一个基本的流可视化设置由高功率的激光和光学透镜组成, 用于生成激光片、照相机、示踪粒子发生器和数据处理器。风洞的设置, 所涉及的设备的规格, 以及相应的参数设置取决于要获得的流量特征。
正常的烟线流动可视化使用烟线来证明流动 streaklines。然而, 在复杂流场中, 由于空间分辨率差, 该方法的性能受到限制。为此, 研制了一种改进的烟气流动可视化技术。该技术同时说明了大规模的全球列流场和小尺度剪切层流结构, 为以后详细的粒子图像测速 (PIV) 测量提供了宝贵的参考。
本文介绍了改进的烟气流动可视化和 PIV 测量在三角洲机翼非恒定流现象研究中的应用。列举了风洞安装、数据采集、数据处理等实验过程和注意事项。结果表明, 这两种流动可视化方法是对三维流场进行定性和定量研究的有效方法。

图 2d显示了列在分解位置的时间历史记录。黑色曲线表示左舷, 红色曲线指示右舷列列。时间尺度由自由流速度和弦长 nondimensionalized。这两次历史的相关系数为r = −0.53, 表明了列的击穿位置振荡的强反对称相互作用。此结果与其他13、19、20的工作很好地吻合。
<p class="jo...

Watch this Scientific Journal Video about Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods at JoVE.com

Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods

在这里, 我们提出了一种通过改进的烟雾流可视化技术来观察三角洲机翼上非恒定涡流流的协议, 并研究了导致前缘涡击穿位置振荡的机制。

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Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM)

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy ATOM

微流控成像流式细胞仪通过不对称检测时间延伸光学显微镜（ATOM）

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the ...

Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

利用 Microfabricated 表面离子阱捕获离子的实验方法

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

流动辅助介: 一种低成本的制备高性能溶液可纳米线器件的方法

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...