中文摘要：

针对设置有低温换热装置和轴流风机的矩形流道，为了合理匹配风机与矩形流道的特性，保证流道内高效地换热，文章采用粒子图像测速（particle image velocimetry，PIV）技术研究了轴流风机出口流场随流道进口宽度的变化规律，并对流道内换热器的整体换热量进行了计算。实验结果表明：随着流道宽度的增加、流道阻力的减小，风机出口流场由径向向轴向转变，转变过程极短，但流场状态基本保持不变，在叶顶对应的主流和中心回流之间均存在涡流，随着向下游的发展迅速耗散；在受限进风条件下，风机前后大压差阻碍气流的轴向运动，叶片周向作用力为气流提供周向速度，当形成的离心力大于叶片的径向力时，将改变风机出口气流的流向；蒸发器的换热量并不随进口宽度的增加而线性变化，但气流流动阻力的减小加强了与蒸发器的热交换，导致换热量总体增大。

英文摘要：

In order to reasonably match the characteristics of axial fan and rectangular channel, guaran- tee the high efficiency of heat transfer in the rectangular channel, which is set with heat exchanger and axial fan, the changing laws of flow field at downstream of axial fan under different inlet width of channel are studied using particle image velocimetry（PIV） technique, and the quantity of heat transfer is alsol calculated. The results show that with the decrease of the resistance due to the increase of inlet width, the outlet flow field of fan is changed from radial direction to axial direction, and the transition process is very short, but the flow state remains unchanged basically, vortex exists between the main flow in the tip and the backflow in the center and dissipates quickly with the development of the down-stream. The large pressure difference between fan inlet and outlet hinders the axial flow of air under restricted air intake conditions, and the force on the air provides the circumferential velocity, when the centrifugal force is greater than the radial force, the direction of air flow will be controlled. The heat exchange of evaporator is not linear with the increase of inlet width, but the overall heat transfer rate increases due to the decrease of flow resistance.