The use of axial fans for cooling is one of the common ways for cooling the power electronic components.Through the analysis of the air flow velocity at the outlet section of axial fan,it can be inferred that the air flows is in a similar thread shape in the chassis.When the circuit board position is different,the local surface heat transfer coefficient (hx) is also different.Experimental analysis combined with simulation models were used to study the change law of hx.The experimental results were in good agreement with the simulation results,the results showed that the distribution law of the local surface heat transfer coefficient will change when the position of the circuit board is changed only in the vertical dir-ection.When the circuit board parallel cooling fan center axis placed horizontally,and the long side of the circuit board and the cooling fan center axis parallel,hxfirstly decreased and then increased along the length of the circuit board,the change of the vertical position of the circuit board mainly affected the variation law along the width of the circuit board,and with the distance from the hub center increased,the circuit board on the higher temperature along the width of the circuit board in the direction of the circuit board to move the edge.Which can provide an important basis for the installation of the cooling fan and the thermal design of the circuit board,and has great significance to the thermal design of electronic equipment.%电子机箱采用轴流式风机进行强迫通风散热是电力电子元件比较常用的散热方式,通过对轴流式风机出口截面空气流速的分析,可以推论出空气以类似螺纹状形态在机箱内流动,从而猜测电路板位置不同时局部表面传热系数(hx)变化规律也是不同的.采用实验分析与仿真模型相结合的办法对hx的变化规律进行了研究.实验结果与仿真结果基本吻合,结果表明,当只改变电路板竖直方向的位置时局部表面传热系数h 分布规律也会发生改变,当电路板平行散热风扇中心轴水平放置,且电路板的长边与散热风扇中心轴平行时,hx沿电路板的长度方向的变化是先减小后增大的,电路板竖直方向位置的改变主要影响hx沿电路板宽度方向的变化规律,且随着距离轮毂中心距离的增大,电路板上元器件温度较高的位置沿电路板的宽度方向由电路板的中间位置不断向边缘移动.此研究能够为散热风扇安装位置以及电路板的热设计提供重要的依据,对电子设备的热设计具有重要的意义.
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