论文标题
撞击湍流喷气
Erosion of cohesive grains by an impinging turbulent jet
论文作者
论文摘要
在各种情况下，例如清洁表面或航天器降落期间，观察到空气中湍流射流的侵蚀和运输。粒子间内聚力的存在会改变侵蚀阈值，超出其传输谷物。凝聚力还会影响陨石坑的形成和形状。在本文中，我们表征了凝聚力在扁平颗粒床侵蚀中的作用，该床上会影响空气中的正常湍流射流。我们使用粘体控制的颗粒材料进行实验，以精细调整颗粒之间的内聚力，同时保持其他特性恒定。我们研究了凝聚力对侵蚀阈值的影响，并表明结果可以通过说明粒子间凝聚力的内聚屏蔽数字合理化。尽管湍流的喷气机具有复杂的性质，但我们仍可以根据喷嘴的出口速度与局部粘性盾牌数字相关联的定律定律，以将射流侵蚀阈值与射流侵蚀阈值相关联。晶粒之间的内聚力也会改变所得火山口的形状，谷物的运输和局部侵蚀过程。
The erosion and transport of particles by an impinging turbulent jet in air is observed in various situations, such as the cleaning of a surface or during the landing of a spacecraft. The presence of inter-particle cohesive forces modifies the erosion threshold, beyond which grains are transported. The cohesion also influences the resulting formation and shape of the crater. In this paper, we characterize the role of the cohesive forces on the erosion of a flat granular bed by an impinging normal turbulent jet in air. We perform experiments using a cohesion-controlled granular material to finely tune the cohesion between particles while keeping the other properties constant. We investigate the effects of the cohesion on the erosion threshold and show that the results can be rationalized by a cohesive Shields number that accounts for the inter-particles cohesion force. Despite the complex nature of a turbulent jet, we can provide a scaling law to correlate the jet erosion threshold, based on the outlet velocity at the nozzle, to a local cohesive Shields number. The presence of cohesion between the grains also modifies the shape of the resulting crater, the transport of grains, and the local erosion process.
