- 學位論文
限制圓狀空氣噴流陣列衝擊於靜止或旋轉多晶片模組圓盤之散熱最佳化研究
Thermal Optimization for a Confined Stationary or Rotating MCM Disk with Round Air Jet Array Impingement
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摘要
在本研究中成功地建立了一系列的實驗系統與量測方法，分別針對靜止或旋轉多晶片模組圓盤在受到不同冷卻技術之下的暫態到穩態熱流特性來做一系列的研究與探討。在本研究中的實驗設計方法是採用統計學上的中央合成設計方法來規劃整個實驗參數組合。研究中所探討的相關參數包括: 穩態葛拉雪夫數、限制板間距與圓盤直徑比、噴流間距與噴嘴直徑比、噴流雷諾數以及旋轉雷諾數。這些參數的探討範圍是Grs = 2.32 ×105 - 2.57×106, H/D = 0.083 - 1.2, H/d = 0.83 - 14.4, Rej = 89 - 17364 與 Rer = 0 - 2903。同時也針對影響靜止或旋轉多晶片模組圓盤在不同冷卻技術之下的暫態到穩態熱流特性相關參數分別做探討分析。並且利用統計學上的變異數分析方法來做敏感度分析測試可定量地分析出系統中相關參數影響之重要性，接著應用反應曲面法搭配數值最佳化方法來有效的求出在各種限制條件下的最佳化散熱研究設計組合。 在本研究中之冷卻技術可分為以下六種：(一)靜止圓盤之自然對流、(二)旋轉圓盤之強制對流、(三)限制圓狀空氣噴流衝擊於靜止圓盤之強制對流、(四)限制圓狀空氣噴流衝擊於旋轉圓盤之混合對流、(五)限制圓狀空氣噴流陣列衝擊於靜止圓盤之強制對流、(六)限制圓狀空氣噴流陣列衝擊於旋轉圓盤之混合對流。 在流場特性方面，所探討的流力特性包括: 噴嘴出口附近的噴流速度與紊流強度分佈、噴流潛變中心長度、沿噴流中心線之噴流速度衰減與紊流強度變化情形以及加熱面附近的流場特性。從實驗量測結果顯示：對於限制圓狀空氣噴流單一噴嘴衝擊而言其流場分佈是屬於對稱性的流場，而限制圓狀空氣噴流陣列衝擊其流場則是屬於非對稱性的流場分佈。而在噴嘴出口的流場觀察僅可分成初始過渡轉變區以及全紊流發展區域。在本空氣噴流陣列衝擊研究中並沒有觀察到初始層流發展區域這個區間，這是與傳統限制圓狀空氣噴流單一噴嘴衝擊不同之處。此外，為了評估限制圓狀空氣噴流陣列衝擊於靜止或旋轉多晶片模組圓盤之流場特性對於各個噴嘴出口的噴流潛變中心長度之影響，在本研究中分別對於特定的噴嘴出口提出了新的經驗公式，此公式可以準確地用來預測限制圓狀空氣噴流陣列衝擊於靜止或旋轉多晶片模組圓盤之各個不同噴嘴出口的噴流潛變中心長度值。 在熱傳特性方面，分別針對在不同冷卻技術下的暫態到穩態之局部和平均熱傳特性來做探討，從實驗量測結果顯示：在限制圓狀空氣噴流陣列衝擊之下其溫度場分佈是屬於對稱性的分佈。亦針對停滯點、局部和平均熱傳特性來做探討分析。並且對於靜止或旋轉多晶片模組圓盤在不同冷卻技術之下其自然對流、圓盤旋轉以及限制圓狀空氣噴流衝擊之間的交互影響來做定量上的研究分析。在研究中更分別對於停滯點、局部和平均紐塞數提出新的經驗公式。同時，為了詮釋圓盤旋轉和空氣噴流衝擊之間的交互作用對於多晶片模組圓盤之對流熱傳特性的影響，在本研究中亦分別針對限制圓狀空氣噴流單一噴嘴與陣列衝擊提出兩條新的經驗公式，當在某特定的限制高度以及旋轉雷諾數與噴流雷諾數比值之下時，可用來區分出圓盤旋轉和噴流衝擊兩類熱傳模式。另外，針對在相同的參數條件之下時，限制圓狀空氣噴流陣列衝擊與傳統限制圓狀空氣噴流單一噴嘴衝擊在熱傳上的增益效果來做探討分析，並且提出一條新的經驗公式來預測空氣噴流陣列衝擊之下的熱傳增益量。 最後，在本研究中更針對平均穩態紐賽數以及平均穩態熱傳係數成功地發展出一套應用於不同冷卻技術之下的散熱最佳化研究設計方法，此方法可使設計者有效且快速地在多個限制條件之下找出最佳化的散熱研究設計組合。首先，利用工程統計分析所作出的敏感度測試可定量地分析出系統中相關參數影響之重要性；接著應用反應曲面法搭配實驗計劃法來得到迴歸曲面模型；最後再藉由數值最佳化方法來有效的求出在各種限制條件下的最佳化散熱研究設計。應用此最佳化方法及流程，可以成功地對於多晶片模組圓盤在不同冷卻技術之下得到各種限制條件下的散熱最佳化研究設計結果。研究中更對於工業界實務應用上，進一步地提出一條新的經驗公式，來評估總輸入能源消耗與系統所得到的最佳化平均穩態熱傳係數之間的關係。
並列摘要
A series of experimental investigations with stringent measurement methods on the studies related to fluid flow and heat transfer characteristics of a stationary or rotating MCM disk with various cooling techniques have been performed. The total experimental cases for a stationary or rotating MCM disk with various cooling techniques are statistically designed by the Design of Experiments (DOE) together with Central Composite Design method (CCD). The relevant parameters influencing fluid flow and heat transfer performance for a stationary or rotating MCM disk with various cooling techniques include: steady-state Grashof number (Grs), ratio of the confinement spacing to disk diameter (H/D), ratio of jet separation distance to nozzle diameter (H/d), jet Reynolds number (Rej) and rotational Reynolds number (Rer). The ranges of the above-mentioned parameters are: Grs = 2.32 ×105 - 2.57×106, H/D = 0.083 - 1.2, H/d = 0.83 - 14.4, Rej = 89 - 17364 and Rer = 0 - 2903. Their effects on fluid flow and heat transfer characteristics for a stationary or rotating MCM disk with various cooling techniques have been systematically explored. In addition, a sensitivity analysis, the so-called “ANOVA”, for the design factors has been performed. An effective optimal method with the RSM and SQP techniques for performing the thermal optimization of a stationary or rotating MCM disk with various cooling techniques under multi-constraints has been successfully developed. Six subtopics of thermal optimization have been systematically explored. They are (1) a confined stationary MCM disk in natural convection; (2) a confined rotating MCM disk; (3) a stationary MCM disk with confined single round jet impingement; (4) a confined rotating MCM disk with single round jet impingement;(5) a confined stationary MCM disk with round jet array impingement; and (6) a confined rotating MCM disk with round jet array impingement. In hydrodynamic aspect, the fluid flow characteristics including the streamwise velocity and turbulence intensity distributions at nozzle exits, jet potential core length, streamwise velocity decay along jet centerline and turbulence intensities evolution along jet centerline are investigated. The flow behaviors for single round jet and for jet array impingement have been experimentally verified as a symmetrical flow and an unsymmetrical flow, respectively. Based on the measurement of the above-mentioned jet flow characteristics for jet array impingement, the jet flow behaviors at nozzle exits can be classified into two regimes such as “initially transitional flow regime” and “initially turbulent flow regime.” Additionally, new correlations of the ratio of potential core length to nozzle diameter, Lpc/d, in terms of relevant influencing parameters for a confined stationary or rotating MCM disk with single round jet and round jet array impingement at various nozzle jets are presented. In heat transfer aspect, from all the experimental data measured for transient-/steady-state local and average heat transfer characteristics, the thermal behavior has been verified to be axisymmetrically maintained and the results have been achieved in an axisymmetric form. The stagnation, local and average heat transfer characteristics for a stationary or rotating MCM disk with various cooling techniques are successively explored. Besides, the mutual influences among buoyancy, disk rotation and jet impingement on the heat transfer performance of a confined stationary or rotating MCM disk with round jet array impingement have been quantitatively evaluated. New correlations of stagnation, local and average Nusselt numbers in terms of relevant parameters are proposed. To interpret the convective heat transfer characteristics on the confined stationary or rotating MCM disk surface due to the mutual effects among jet impingement and disk rotation, the heat transfer behavior can be classified into two distinct heat transfer regimes such as disk rotation-dominated regime and jet impingement-dominated regime for the cases with a specified ratio of rotational Reynolds number to jet Reynolds number, i.e., . Two empirical correlations of classifying these two distinct regimes are proposed for the single round jet and jet array impingement, respectively. The steady-state heat transfer enhancement for jet array impingement compared with single round jet impinging onto a confined stationary or rotating MCM disk has been systematically explored; and a new correlation of the heat transfer enhancement ratio, , in terms of relevant influencing parameters is reported. Furthermore, a series of thermal optimizations with multiple constraints such as space, jet Reynolds number, rotational Reynolds number, nozzle exit velocity, disk rotational speed and total power consumption constraints for a stationary or rotating MCM disk with various cooling techniques have been performed and discussed. New correlations of the optimal steady-state average heat transfer performance for the cases of a confined stationary or rotating MCM disk with single round jet or jet array impingement are finally presented.
參考文獻
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