Abstract Floatation nozzle is a key component for manufacturing high performance substrates in the roll to roll processes because it can support the substrate without contact. The heat transfer and pressure distribution of the floatation nozzle, which is highly associated with the flow dynamics, greatly affect drying/heating/cooling efficiency and operating costs of the nozzle. However, the flow dynamics and heat transfer of the floatation nozzle have not well been understood. In this study, a large eddy simulation model validated against experimental result and proper orthogonal decomposition were employed to study the flow dynamics and heat transfer of floatation nozzle. In addition, the large eddy simulation results of confined slot jet and unconfined slot jet impinging on a vertical surface were provided to get an in-depth understanding of the floatation nozzle. We found that a secondary stagnation region was existed in the floatation nozzle which did not appear in a single slot jet and was quietly different than that of multiple jets. Moreover, the primary and secondary vortices of the floatation nozzle and slot jets were identified by proper orthogonal decomposition method and instantaneous flow field. Furthermore, heat transfer mechanisms in different regions were illustrated, and the reasons of primary and secondary Nusselt number peaks were explained. Finally, it was found that an air cushion is generated for floatation nozzle, which leaded to the floatation ability of the floatation nozzle is about 20 times as much as that of the unconfined slot jet.

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基于大涡模拟和适当正交分解法的浮选喷嘴流动动力学和传热特性分析

摘要 浮动喷嘴是卷对卷工艺中制造高性能基板的关键部件，因为它可以无接触地支撑基板。浮选喷嘴的传热和压力分布与流动动力学高度相关，极大地影响了喷嘴的干燥/加热/冷却效率和运行成本。然而，漂浮喷嘴的流动动力学和传热尚未得到很好的理解。在这项研究中，采用与实验结果和适当的正交分解进行验证的大涡模拟模型来研究浮选喷嘴的流动动力学和传热。此外，提供了受限狭缝射流和非受限狭缝射流撞击垂直表面的大涡模拟结果，以深入了解浮选喷嘴。我们发现在浮选喷嘴中存在二次滞流区，该区域不出现在单缝射流中，与多射流的情况不同。此外，通过适当的正交分解方法和瞬时流场识别了浮选喷嘴和狭缝射流的初级和次级涡。此外，阐述了不同区域的传热机理，并解释了初级和次级努塞尔数峰值的原因。最后发现浮子喷嘴产生了气垫，