本文主要是藉由改變風扇之上、下游系統阻抗，研究相關散熱元件之性能與噪音變化。首先，將一片遮蔽板放置於風扇上游，並改變遮蔽板與風扇之間的距離，使風扇上游的流阻改變，以評估其對性能與噪音之影響。在軸流風扇方面，遮蔽效應對風扇的大小或厚度都有一致的結果，且遮蔽板對靜壓的影響較流量大；以6025為例，當遮蔽板距軸流風扇入風口10 mm時，其流量比例尚有83.8%，但靜壓比例卻只剩下35.4%。由於遮蔽板的距離在10 mm以下，才會對散熱模組的熱特徵參數有明顯影響，所以風扇入風口前方應保持至少10 mm的無阻礙物距離，以避免影響散熱模組之性能。在離心風扇方面，與軸流扇不同的是遮蔽板對靜壓與流量之影響相差不多，以6015單進風離心扇為例，當遮蔽板距離風扇入風口只有2 mm時，其流量比例為64.4%、靜壓比例為63.9%；在散熱模組性能方面，遮蔽板要移到4 mm以內才會有明顯影響，其抗阻抗性優於軸流風扇。此外，在探討風扇下游的流阻大小對散熱模組影響方面，本文藉由斜鰭片與直鰭片散熱座之性能比對，來證實具備低流阻之斜鰭片，在低轉速時可以凸顯出其優越性；如在2,000 rpm運轉時，其熱特徵參數值只降低了0.07 ℃/W，但由於CPU模擬器的功率高達82W，所以兩者在散熱座底部的最大溫度，可達約6℃。綜而言之，系統流阻對於風扇單體甚至散熱模組之性能與噪音影響都極為重要，對於散熱需求日益增高的電腦而言，本研究成果可作為電腦散熱設計之參考。

From earlier experience, it is well known that heat-dissipating effect varies significantly for different PC layouts, which diminishes fan performance by blocking its flow path. Thus, there is a substantial demand existed for researchers to realize this blockage effect systematically. As a consequence, this study investigates the blockage effect on the performance and noise characteristics of axial-flow and centrifugal fans applied on heat sink assembly. To simulate the blockage effect, a flat plate is placed at a certain distance on the top of the cooling fan to partially block its flow path. Experimental and numerical results show that the blockage effect has greater influence on the static pressure of the axial-flow fan than its flow rate but the blocking board provokes almost the same influences on the static pressure and flow rate for centrifugal fan. For instance, when the blockage distance is 4 mm, centrifugal fans are capable of maintaining at least 70% of its performance. However, the flow resistance in the axial-flow fan is so great that the flow becomes stagnant. Based on these findings, centrifugal fans are apparently more suitable for environment with high resistance. Also, from experimental verification, the centrifugal fan maintains a higher capability of heat removal since its static pressure is higher. Regarding the heat management, the blockage plate has nearly no effect for a large blockage distance; however, a steep decrease of thermal characteristic parameter is found for a small blockage distance.
In addition, to reduce this undesired blockage on the airflow, oblique planar fins are utilized in heat sink assemblies to improve the overall performance of the heat sink assembly. In addition, a high-pressure, axial-flow fan (70×70×15 mm3) is designed to incorporate with the conventional vertical and novel oblique fins to form complete heat sink assembly units. Experimental results indicate that, due to the larger surface area and accelerating flow between the fins, the heat sink assembly with oblique planar fins shows better performance than that with typical vertical fins. For the case of high-pressure fan operating at 2000 rpm, the extra cooling effect could result in a reduction of 6 on the CPU case temperature by introducing oblique fins. Obviously, the flow resistance of heat sink is an important factor for determining the overall performance of heat sink assembly.

中文摘要 I
英文摘要 II
誌謝 IV
目錄 V
圖索引 VIII
表索引 XIII
符號索引 XV
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 8
1.2.1 軸流扇 8
1.2.2 離心扇 9
1.2.3 散熱座 12
1.3 研究動機與方法 14
1.4 本文架構 17
第二章 風扇設計 19
2.1 軸流風扇 19
2.1.1 三維葉片 19
2.1.2 三維葉輪 24
2.2 離心風扇 30
2.2.1 葉輪 32
2.2.2 風機外殼 35
第三章 數值模擬 38
3.1 流場統御方程式 38
3.2 紊流模式 39
3.3 數值方法 41
3.3.1 離散法則 43
3.3.2 上風差分法 43
3.3.3 SIMPLE解法理論 46
3.4 數值邊界條件 48
3.5 模型格點之建立 50
3.5.1 軸流扇 51
3.5.2 離心扇 54
3.6 軸流扇之模擬結果與分析 57
3.6.1 軸流扇之流場分析 58
3.6.2 軸流扇之參數分析 65
3.7 輻射葉片離心扇之模擬結果與分析 67
3.7.1 離心扇之流場分析 68
3.7.2 離心扇之參數分析 74
3.8 實驗與模擬之驗證 76
第四章 實驗設備及儀器 79
4.1 風扇性能量測設備 79
4.2 噪音量測設備與環境 88
4.2.1 聲壓量測系統 88
4.2.2 量測環境 88
4.3 散熱器性能量測設備與環境 89
4.3.1 散熱器性能量測設備 89
4.3.2 恆溫環境系統 93
4.3.3 感測器之校正 95
第五章 實驗規劃程序與結果討論 97
5.1 軸流扇之遮蔽效應 100
5.1.1 實驗規劃 100
5.1.2 結果與討論 102
5.2 離心扇之遮蔽效應 118
5.2.1 實驗規劃 119
5.2.2 結果與討論 119
5.2.3 遮蔽效應對散熱模組之影響 131
5.3 不同風扇型式之比較 136
5.3.1 風扇單體之性能 137
5.3.2 散熱模組之性能 140
5.4 低流阻之散熱座 141
5.4.1 實驗規劃 143
5.4.2 結果與討論 145
第六章 結論與建議 156
6.1 結論 156
6.2 建議 159
參考文獻 162
作者簡介 167

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