Abstract

This paper experimentally studies a new method to enhance heat transfer in which a soft textile flap flutters and slaps a hot plate surface, due to fluid-structure interaction. The self-sustained periodic slapping of the textile flap against the heat transfer surface disrupts the boundary layers and thus, increases the heat transfer between the air and plate surface. Heat transfer coefficients in the presence of textile flaps of different shapes and sizes were measured while oscillatory motion of the flaps was recorded. The results show that rectangular flaps provide consistent heat transfer enhancement with increases in heat transfer coefficient observed of up to 42%, from 113 W·m⁻²·K⁻¹ in the absence of a textile flap, to 161 W·m⁻²·K⁻¹ in the presence of a rectangular textile flap, at a wind speed of 18.5 m·s⁻¹ . It is found that the Nusselt number in the presence of rectangular flaps varies with the flap oscillation frequency in a nonlinear fashion and that the maximum heat transfer coefficient generally occurs when the dimensionless flow-induced oscillation frequency is in the range of 0.22 to 0.32. These results show the potential of using self-sustained oscillating textile flaps to enhance the convective heat transfer in various heat exchangers.

摘要

本文通过实验研究了一种增强传热的新方法，在该方法中，由于流体-结构的相互作用，柔软的纺织品翻盖会拍打并拍打热板表面。纺织品翼片在传热表面上的自持周期性拍打破坏了边界层，因此增加了空气和板表面之间的传热。测量了存在不同形状和尺寸的皮瓣时的传热系数，同时记录了皮瓣的振荡运动。结果表明，矩形襟翼可提供一致的传热效果，观察到的传热系数提高了42％，从无纺织物襟翼的113 W·m ^-2 ·K ^-1增至161 W·m ^-2 ·K ^-1在存在矩形纺织翻盖的情况下，风速为18.5 m·s ^-1。已经发现，存在矩形襟翼的努塞尔数以非线性方式随襟翼振荡频率而变化，并且最大导热系数通常在无因次流动引起的振荡频率在0.22至0.32的范围内时发生。这些结果表明，使用自持的摆动式纺织品翻盖来增强各种热交换器中对流换热的潜力。