Atmospheric ice accretion results from the exposure of technical equipment or facilities to cold and humid environments. Supercooled droplets in a cloud can impact an airplane's surface and quickly form an ice layer. The presence of air pockets in such a layer is well known and explains the white appearance of some of the accretions. However, estimation of its porosity values and studies on the pore formation mechanics remain limited. In this study, we performed tests in an icing wind tunnel and scans with micro-computed tomography to address these issues. Here, we show that the accretion has closed porosity below 1%, which is mostly produced by the interaction between a spray-like impact on the water surface. The insights we provide here are important to improve ice accretion modelling techniques and establish a different approach to address the interaction between the cloud and the surfaces exposed to atmospheric icing.

中文翻译：

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大气结冰过程中孔隙度的形成：使用微型计算机断层扫描的测量

大气结冰是由于技术设备或设施暴露于寒冷和潮湿的环境中造成的。云中的过冷液滴会撞击飞机表面并迅速形成冰层。在这样的层中存在气穴是众所周知的，并解释了一些附着物的白色外观。然而，对其孔隙度值的估计和对孔隙形成力学的研究仍然有限。在这项研究中，我们在结冰风洞中进行了测试，并使用微型计算机断层扫描来解决这些问题。在这里，我们表明吸积物的闭合孔隙率低于 1%，这主要是由水表面上的喷雾状冲击之间的相互作用产生的。