• 沒有找到結果。

本研究以 STAR-CD 套裝軟體為計算平台,模擬三維冷卻渠道在不同雷諾數

,隨著往復式運動並考慮自然對流的條件下,探討流場的變化,及比較熱傳效

。此模擬並與實驗做同步對照,以驗證模擬的真實性,經模擬結果並結合前述 章節之內容可獲得以下結論:

1. 渠道在靜止或是振動時,熱傳效益隨著流體雷諾數增加。除了在 Re=150 時熱傳效益不受振動頻率增加而增加,其餘的 Re 下皆會隨著振動頻率增 加,整體熱傳效益也會隨之增加。

2. ㄇ型渠道在靜止或是振動的情況下,熱傳效益皆是前段加熱區熱傳效率最 好、中段加熱區次之,後段加熱區最差。

3. 當渠道振動時,在 下

益 各

1 週期時因為渠道向下,使得渠道內體積增加,為了4 補充多出的體積而導致流體有回吸的現象,此現象使得流體加熱時間增 加,熱傳效益因此較差。在

3 週期時,此時渠道正往上,因為相對速度4 的關係使得冷卻流體衝擊壁面的力量增強,且渠道幾何形狀改變,導致流 體加速,而使帶走熱量的速率增加,所以此時熱傳效率最好。

4. 當渠道振動時,後段加熱區因為迴流受到渠道振動時的破壞,使得囤積的 熱量被打散,所以在任何週期時,後段加熱區之熱傳效益普遍比靜態時佳。

5. 當渠道在振動時,熱傳效率相對於靜止時改善許多,本模擬最大整體 Nu 增 加率可達 56.6%。

6. ㄇ型渠道在作往復運動時,在各週期流場變化極為相似, Nu 會產生類似 的週期性變化。

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