Improved Flow Visualization Methods Based on the Background Oriented Schlieren Technique
Improved Flow Visualization Methods Based on the Background Oriented Schlieren Technique
复制标题
基于背景导向纹影技术的改进流可视化方法
DOI：
10.1299/kikaib.77.2391
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
S. Honami
中科院分区：
文献类型：
--
作者：
J. Akatsuka;S. Nagai;S. Honami
本文提出了两种新的基于背景纹影技术的可压缩流动显示方法。一种是“简化的面向背景的纹影（S-BOS）“。该技术不需要通常在BOS中使用的互相关算法。数据处理比原始BOS简单得多，因为与密度梯度相关的图像位移是从具有周期性背景图案的图像的强度代数计算的。此外，它可以轻松地使我们实现数据处理的自动化，因为既不需要删除不正确的向量，也不需要优化询问窗口和搜索窗口等参数。另一种是基于小波的背景定向纹影（W-BOS）。这种技术提供了一个纹影图像使用连续小波变换的周期性背景图案。通过将周期性的强度图案转换为相位，可以容易地获得纹影图像。由于这两种技术中的光学设置比传统纹影成像的光学设置简单，因此它们可以用于包括现场测试在内的各种情况。在1 m × 1 m超声速风洞中进行了风洞试验。通过与传统纹影图像的比较，证明了它们的实用性。
This paper propose two new flow visualization methods based on the Background-Oriented Schlieren (BOS) technique for compressible flow. One is “Simplified background-oriented schlieren (S-BOS) ”. This technique does not require a cross-correlation algorithm, which is typically used in BOS. The data processing is much simpler than that of the original BOS, since image displacement associated with density gradient is algebraically calculated from intensities of the images with the periodic background pattern. Moreover, it easily allows us to automate the data processing, because it is neither necessary to remove incorrect vectors nor to optimize parameters such as the interrogation window and search window. The other is referred to “Wavelet-based background-oriented schlieren (W-BOS)”. This technique provides a schlieren image using continuous wavelet transformation for the periodic background pattern. By transforming the periodic intensity pattern into the phase, a schlieren image can be obtained easily. Since the optical setup in both techniques is simpler than that of a conventional schlieren imaging, they could be used in various situations including field tests. A wind tunnel test was conducted in a 1 m × 1 m supersonic wind tunnel. Their usefulness was demonstrated by comparing with the conventional schlieren images.