This paper introduces a novel image processing methodology to enable an extension of the range of applicability of the back-lit imaging method to provide the simultaneous measurement of size and velocity in turbulent flows with a high concentration of objects having various shapes and sizes. The new image processing methodology applies an interrogation-window method similar to that used in particle image velocimetry, alongside interface identification as used in backlight imaging. The matching of droplets or particles of arbitrary shape is achieved by dividing the image into several small windows and cross-correlating objects in each window to obtain a coefficient of dissimilarity, extracted using a variety of metrics of droplet or particle morphology. To demonstrate its utility this technique is applied to measurement of velocities from (i) a highly turbulent spray flow and (ii) a swirling particle-laden flow as applicable to dry powder inhalation systems. Results are validated against phase Doppler anemometry data and a sensitivity analysis of the controlling parameters of the image processing methodology demonstrate that the technique is robust for a variety of input conditions. A key advantage of this approach lies in complementing the diagnostics capability of PDA methods to span a broader range of particle sizes irrelevant of shape and particle concentration.

本文介绍了一种新颖的图像处理方法，可以扩展背光成像方法的适用范围，从而可以同时测量湍流中具有各种形状和大小的高浓度对象的大小和速度。新的图像处理方法应用了类似于粒子图像测速的询问窗口方法，以及背光成像中使用的界面识别。通过将图像划分为几个小窗口并使每个窗口中的对象相互关联以获得不相似系数，可以使用各种液滴或颗粒形态度量来提取任意形状的液滴或颗粒的匹配。为了证明其实用性，该技术适用于测量以下各项中的速度：（i）适用于干粉吸入系统的高度湍流的喷雾流和（ii）充满旋流的颗粒流。针对相位多普勒风速计数据验证了结果，并且对图像处理方法的控制参数进行了敏感性分析，结果表明该技术对于各种输入条件都非常可靠。该方法的主要优势在于，可以补充PDA方法的诊断能力，以覆盖与形状和颗粒浓度无关的更宽范围的粒径。针对相位多普勒风速计数据验证了结果，并且对图像处理方法的控制参数进行了敏感性分析，结果表明该技术对于各种输入条件都非常可靠。该方法的主要优势在于，可以补充PDA方法的诊断能力，以覆盖与形状和颗粒浓度无关的更宽范围的粒径。针对相位多普勒风速计数据验证了结果，并且对图像处理方法的控制参数进行了敏感性分析，结果表明该技术在各种输入条件下均十分可靠。该方法的主要优势在于，可以补充PDA方法的诊断能力，以覆盖与形状和颗粒浓度无关的更宽范围的粒径。