内置翅片参数对封闭腔内流体流动与传热性能的影响

Influence of Built-in Fin Parameters on the Flow and Heat Transfer Performance in Enclosed Cavity

为了研究内置翅片参数对封闭腔内湍流自然对流换热的影响,采用RNG k-ε模型数值分析了翅片位置、翅片高度和翅片数量对封闭腔内温度场和流场的综合影响。结果表明:在高度为H的腔体热壁面上布置1个翅片,热壁面竖向边界层厚度随翅片高度的增大而变厚,但腔体顶部水平边界层结构变化微弱;本文所研究的短翅片高度对热壁面上远离翅片位置处局部传热特性影响很小;在热壁面上距底面2H/6处布置高度为1.5 cm的翅片能使得热壁面上平均Nu获得最大值,在热、冷壁面上距底面及顶面分别为2H/6处各布置1个高度为1.5 cm的翅片能达到同样的强化传热效果。但在热、冷壁面上距底面及顶面分别为H/6处各布置1个翅片时,翅片高度过大或过小均会抑制热壁面与腔内气流之间的对流换热过程。本文研究结果对于指导工业工程中封闭空间内流体的冷却或加热具有一定的理论参考价值。

In order to study the influence of built-in fin parameters on the heat transfer of turbulent natural convection in the enclosed cavity with the height H, the RNG k-ε model was used to numerically analyze the comprehensive effects of the fin position, the fin height and the fin number on the temperature and flow field. Result Shows as follows. When single fin is arranged on the hot wall, the thickness of the vertical boundary layer close to the hot wall becomes thicker with the increase of the fin height, but the structure of the horizontal boundary layer close to the top of the cavity changes slightly. The height of the short fin studied has little effect on the local heat transfer characteristics at the location away from the fin on the hot wall. The average Nusselt number on the hot wall can reach the maximum value when the fin with the height of 1.5 cm is arranged at 2H/6 from the bottom of the hot wall, and the same average Nusselt number on the hot wall can be achieved by placing one fin with the height of 1.5 cm on the hot wall at 2H/6 from the bottom and the other on the cold wall at 2H/6 from the top of the cavity. When a fin is arranged on the hot wall at H/6 from the bottom and the other on the cold wall at H/6 from the top of the cavity, the convective heat transfer efficiency between the hot wall and the airflow in the cavity will be restrained if the fin height is too high or too low. The results have a certain theoretical reference value to guide the cooling or heating of fluid in enclosed space in industry engineering.