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Applied Physics 2021
扭曲矩形管管内传热与压降特性的数值研究
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Abstract:
采用CFD方法对扭曲矩形管的管内传热和压降特性进行了数值研究，得到雷诺数(Re)在5000~40,000范围内不同几何参数的扭曲矩形管传热与压降特性数据，并对其强化传热机理进行了对比分析。结果表明：当5000 ≤ Re ≤ 40,000时，摩擦系数(f)随长宽比(k)的增大而减少，努塞尔数(Nu)随k的增加先增大后减少，在扭曲比(H)为0.4时达到最大；f均会随着扭距(s)的增加而减少，在s为200 mm时达到最大值，且此时扭曲矩形管具有较高的Nu；扭曲矩形管中形成的二次流促进了热边界层内外流体的热量交换，从而提高扭曲矩形管的综合换热性能。
The characteristics of heat transfer and pressure drop in the twisted rectangular tubes are numerically studied by CFD method. Some sets of data about heat transfer and pressure drop characteristics of twisted rectangular tube with different geometric parameters under the Reynolds number 5000~40,000 are obtained. In addition, the mechanism heat transfer enhancement was analyzed by data comparison. The results show that: in turbulent flow, the friction coefficient decreased with the increase of the aspect ratio, and the Nusselt number first increased and then decreased with the increase of the aspect ratio. The Nusselt number reached the maximum when the twist ratio was 0.4. In turbulent flow, the friction coefficient decreased with the increase of the torque, and reached the maximum value when the twisted pitch length was 200 mm, where the twisted rectangular tube had high Nusselt number. The secondary flow in the twisted rectangular tube promotes the heat exchange between the fluid inside and outside the thermal boundary layer, thus improving the comprehensive heat transfer performance of the twisted rectangular tube.
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