过渡流下叉排圆柱列流动传热特性的研究

Study on Flow and Heat Transfer Characteristics of Offset Cylinder Arrays in Transition Flow

为了对冷媒替代引起的小型化换热器内的管束在过渡流下的传热强化机理进行研究,本文对交叉布置圆柱列的流动传热特性进行了数值分析。通过基于复合网格的计算方法,研究了交叉管束随管束中心距变化下的流动与传热特性。计算结果表明,管束横向节距对流场、温度场的状态,上下排管束的传热强化以及压差将产生重要的影响。随着管束横向节距的逐渐增大,前排尾流的不稳定性将加剧下排管束表面附近的流场的不稳定性以及引起流场压差的变化,同时强化下排管束表面附近的传热。

This paper numerically simulated flow and heat transfer characteristics of offset cylinder arrays of the miniaturization heat exchanger caused by refrigerant alternative in order to offer a de- tailed explanation of what the heat transfer mechanism in transition flow is and how the heat transfer is enhanced by the instability occurring in the wake flow of offset cylinder arrays. Characteristics of flow and thermal fields of different cylinder row pitch in an offset cylinder arrays were analyzed by means of compound grid systems. The numerical result demonstrates that cylinder row pitch plays an important role in the states of flow and thermal fields, heat transfer enhancement and the pressure loss. As the cylinder row pitch increases, the unsteady wake flow behind the first row cylinders disturbs the flow around the second row cylinders and enhances the instability of the flow there. This leads to the change of pressure loss and the enhancement of the heat transfer around the second row cylinders.