We describe experiments designed to inform computational models of the dynamic filling process of chemically blown, polyurethane foams, especially subgrid models to predict bubble size affecting foam properties. Three experimental methods are used to observe the evolution of bubble sizes during blowing. Magnified views of bubbles at a transparent wall of a channel are recorded during the foaming. The bubble sizes in the final frame after the expansion has stopped are compared to scanning electron microscope images of the interior of the cured samples to determine wall effects. In addition, diffusing wave spectroscopy is used to determine the average bubble sizes across the width of a similar channel during foam expansion. We conclude that the bubble size distribution is dependent on the formulation of foam being tested, temperature, the height in the foam bar, the proximity to a wall, and the degree of overpacking.

中文翻译：

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聚氨酯泡沫膨胀的气泡尺度观察

我们描述了旨在为化学发泡聚氨酯泡沫动态填充过程的计算模型提供信息的实验，特别是用于预测影响泡沫性能的气泡尺寸的亚网格模型。三种实验方法被用来观察气泡在吹气过程中尺寸的演变。在发泡过程中记录通道透明壁处气泡的放大图。将膨胀停止后最终帧中的气泡尺寸与固化样品内部的扫描电子显微镜图像进行比较，以确定壁效应。此外，扩散波光谱用于确定泡沫膨胀期间类似通道宽度上的平均气泡尺寸。我们得出结论，气泡尺寸分布取决于被测泡沫的配方、温度、