通道中串列倒转柔性体的运动与传热

Heat Transfer Enhancement in a Heated Channel by Inverted Tandem Flags

为研究柔性结构运动对通道换热性能的影响,采用任意拉格朗日-欧拉(Arbitrary Lagrangian-Eulerian,ALE)法,对通道中串列布置的倒转柔性体进行数值模拟。研究不同长宽比的柔性体在抗弯刚度系数相同时的拍动状态、流场特性以及对通道换热性能的影响。结果表明:随抗弯刚度系数变化柔性体存在稳定模式、大幅度拍动模式和偏转拍动模式3种运动模式;随抗弯刚度系数减小,小长宽比柔性体的拍动状态变化具有滞后性;大长宽比柔性体在净换热量提升上更有优势,在合理的机械能损失范围内拥有更高的热效率系数,相较小长宽比通道,平均净换热量提高了3.87倍,最高热效率系数可达1.3;在实际工程应用中,应采用大长宽比并处于大幅度拍动模式下才能有效提升通道内传热性能。

In order to explore the influence of vibration of flexible structures on the heat transfer performance,arbitrary Lagrangian-Eulerian(ALE)method was used to simulate the inverted flexible flags which were arranged in tandem in the channel numerically.The flag vibration,flow field characteristics and their combined effects on the heat transfer performance were studied at the differnet aspect ratios with the same bending stiffness coefficient.The results show that there are three flapping modes with the change of bending stiffness coefficient,such as straight mode,flapping mode and deflection mode.With the decrease of the bending stiffness coefficient,the hysteresis phenomenon is observed at the small aspect ratio.The large aspect ratio has more advantages in the enhancement of net heat flux,and has higher heat transfer efficiency within a reasonable mechanical energy loss.Compared with the small aspect ratio channel,the average net heat flux has increased by 3.87 times,and the highest heat transfer efficiency can reach 1.3.In practical engineering application,the heat transfer in the channel can be effectively enchanced only by adopting the large aspect ratio and keeping in flapping mode.