摘要

本研究是探討不同幾何形狀的風罩對風扇性能與散熱模組性能的影響，主要利用數值計算，分析風扇及散熱器的流場，並分析加裝導風罩之後的流場變化，再使用實驗設備量測各項性能，藉此瞭解導風罩對風扇及鰭片式散熱器的影響並且驗證數值模擬的準確性。在風扇方面，經由數值模擬與實驗驗證，加裝空心圓柱的風罩對風扇性能的影響最鉅，最大靜壓值提昇3.9%，並且最大流量值增加20.9%，但是風扇的噪音值也相對提高3 dBA至6 dBA 。在散熱模組方面，經由數值結果與實驗的驗證得知，雖然安裝導風罩可以提昇風扇的性能但是對散熱模組的熱特徵係數無法有效地降低，主要原因是導風罩會使得風扇的迴流現象變為更劇烈並且造成迴流區的流體逆流出風扇，造成散熱模組性能下降，略微使CPU的溫度升高0.5oC左右。而加裝風罩的散熱模組之噪音與原散熱模組的差異性不大。另外利用數值方法來模擬三種不同材質的散熱器與原散熱器(鋁鰭片銅心柱)性能比較，其計算結果顯示，鋁合金散熱模組的CPU溫度會比原散熱模組的CPU溫度增加3.2oC，鋁鰭片加熱管的CPU溫度會比原散熱模組的CPU溫度降低3.5oC。

關鍵字: 導風罩，風扇，散熱模組。

Abstract

The purpose of the present study is to investigate the effect of different air intake designs on the performance of an axial-flow fan. Four different types of air intake are investigated the inlet and outlet diameters, and the height of all the air intakes are the same, but the profiles of the side wall are different for different intake designs. The four different side wall profiles investigated are: (1) straight and inlet cone type, (2) parabolic type, (3) cone type, (4) hyperbolic type. It is found that axial fan with air intake designs can improve its volume flow rate around 20 ~ 30%, and the maximum static pressure can be improved by up to 6%. The axial fans with different air intakes are the integrated with a heat sink to form cooling modules for the personal computer CPU. The cooling performance of various cooling modules with different fan and heat sink configuration are investigated both numerically and experimentally. The thermal resistances of all the cooling modules are all around 0.2oC/W, and the agreement between the numerical and experimental results is found to be good.

Keywords: air intake, axial fan, cooling modules

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