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畢業論文 燃氣輪機高溫葉片內部冷卻系統DES數值分析和實驗研究

  • 簡介:畢業論文-燃氣輪機高溫葉片內部冷卻系統DES數值分析和實驗研究,共95頁,32705字,中文摘要,內部冷卻是現代燃氣輪機透平葉片設計中不可或缺的冷卻方式,冷卻流量不,足會減小葉片壽命,過多則會降低燃機性能。內部冷卻通道中復雜的三
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文件大小:26.51MB
適用專業:能源動力系統及自動化
適用年級:大學
論文編號:209525

論文簡介:

畢業論文-燃氣輪機高溫葉片內部冷卻系統DES數值分析和實驗研究,共95頁,32705字
中文摘要
內部冷卻是現代燃氣輪機透平葉片設計中不可或缺的冷卻方式,冷卻流量不
足會減小葉片壽命,過多則會降低燃機性能。內部冷卻通道中復雜的三維流動導
致了復雜的傳熱系數分布,準確預測通道內的阻力系數和傳熱分布對于提高內部
冷卻系統的性能具有重要意義。
作者改造并調試了內部冷卻實驗臺,對不同進出口情況下 37000 到 70000 雷
諾數范圍內共計 12 個工況進行實驗,采用瞬態液晶技術獲得了梯形帶肋內部冷
卻通道的詳細傳熱分布。針對實驗工況,分別采用 DES 和 RANS 數值計算模型
研究其流動和傳熱機理。結果表明,梯形通道帶肋壁面的傳熱分布具有非對稱的
特點,努塞爾數與雷諾數正相關,不同雷諾數下努塞爾數分布相似,其傳熱特征
由流動特征決定。斜置肋片會引起二次流,二次流的發展導致進出口段傳熱的沿
程發展;彎頭外側的低速區和彎頭下游的回流區造成相應的低傳熱區域,進而導
致彎頭區傳熱較差;肋片后存在沿肋高長度不等的分離區,流動再附點周圍傳熱
系數最高。相對而言,DES 對于傳熱分布規律的預測比 RANS 準確,但兩種數值
方法均未準確預測彎頭處大分離的影響和通道的非對稱性特征。
此外實驗和數值結果的對比顯示,二次流的影響使中心線溫度不能代表截面
平均溫度,因此實驗數據處理不能采用中心線溫度沿程插值。數值模擬還表明評
價帶肋壁面傳熱效果不能僅關注肋間傳熱,還需將肋片的傳熱量考慮在內。
關鍵詞:燃氣輪機,內部冷卻,梯形帶肋 U 型通道,熱色液晶,DES


ABSTRACT
Internal cooling is widely used in modern gas turbines. Insufficient cooling air
will shorten the blade life while too much cooling air will reduce turbine efficiency.
Complex three-dimensional flow inside the internal cooling duct results in complex
heat transfer distribution. Accurately predicting local heat transfer coefficient and
friction loss is important to improve internal cooling system performance.
The present study focuses on detailed heat transfer coefficient measurements of a
two-pass ribbed trapezoidal channel, using the transient thermochromic liquid
crystal(TLC) technique. Results are presented with both bigger and smaller inlet
sections over a range of Reynolds numbers between 37000 and 70000. Heat transfer
and flow features are also studied using RANS model and detached eddy simulation
(DES).Results show that heat transfer on two ribbed walls is non-symmetric, Nusselt
number increases when Reynolds number increases, however follows a similar
distribution pattern. Heat transfer distribution is determined by the flow field. Skewed
ribs induce secondary flow, heat transfer coefficient increases with the development of
secondary flow in both inlet and outlet sections. Heat transfer is low in the turn region
because of low-velocity regions in the outside turn and flow separation region after the
turn. Behind the rib there are flow separation regions of different sizes, Nusselt number
is high where flow reattaches. Flow development and heat transfer distribution
predicted by DES are more accurate than that predicted by RANS, but both numerical
methods fail to capture the non-symmetry features and the bend effect.
Comparing experimental and numerical results, it’s found that the mainstream
temperature along the centerline can not represent surface-averaged temperature,
indicating that it’s inappropriate to use centerline temperature for streamwise
interpolation during data processing. The numerical results also suggest that heat
transfer rate on the ribs should be taken into consideration together with heat transfer
rate between the ribs.
Keywords: gas turbine, internal cooling, two-pass trapezoidal ribbed duct,
thermochromic liquid crystal,DES


目錄
第 1 章 引 言 ............................................................................................1
1.1 研究背景 ...........................................................................................1
1.2 研究現狀 ...........................................................................................1
1.2.1 實驗研究 .......................................................................................1
1.2.2 數值模擬 .......................................................................................2
1.3 本文研究主要內容 ............................................................................3
第 2 章 瞬態液晶實驗介紹 .......................................................................4
2.1 研究對象的定義 ................................................................................4
2.2 內部冷卻實驗臺 ................................................................................6
2.2.1 實驗臺改造 ...................................................................................6
2.2.2 實驗臺結構 ...................................................................................7
2.3 瞬態液晶測溫原理 ............................................................................9
2.4 實驗工況 .........................................................................................12
2.5 本章小結 .........................................................................................12
第 3 章 內部冷卻通道實驗結果 ..............................................................13
3.1 傳熱分布 .........................................................................................13
3.1.1 不同雷諾數對傳熱的影響 ...........................................................13
3.1.2 不同進出口條件下的傳熱分布 ...................................................17
3.2 無量綱壓力分布 ..............................................................................23
3.3 幾何結構與非對稱性分析 ...............................................................25
3.4 本章小結 .........................................................................................27
第 4 章 脫落渦 (DES)及雷諾平均 (RANS)模擬 ........................................28
4.1 數值模擬方法介紹 ..........................................................................28
4.2 計算模型及計算方法 .......................................................................29
4.2.1 網格分布 .....................................................................................29
4.2.2 邊界條件 .....................................................................................31
4.2.3 數值算法 .....................................................................................31
4.2.4 DES 方法中 LES 及 RANS 使用區域 ...........................................31
4.3 大進口工況傳熱及壓損分析 ...........................................................32
4.3.1 內部冷卻通道傳熱分布比較 .......................................................32
4.3.2 內部冷卻通道無量綱壓力比較 ...................................................37
4.3.3 內部冷卻通道流動分析 ..............................................................38
4.4 小進口工況傳熱及壓損分析 ...........................................................43
4.4.1 內部冷卻通道傳熱分布比較 .......................................................43
4.4.2 內部冷卻通道無量綱壓力比較 ...................................................44
4.5 數值模擬對實驗的指導作用 ...........................................................45
4.5.1 中心線溫度分布 .........................................................................45
4.5.2 忽略肋片傳熱帶來的影響 ...........................................................47
4.6 本章小結 .........................................................................................47
第 5 章 結論與建議 .................................................................................49
5.1 本文結論 .........................................................................................49
5.2 存在不足與改進建議 .......................................................................50
插圖索引 ...................................................................................................51
表格索引 ...................................................................................................53
參考文獻 ...................................................................................................54
致 謝 .........................................................................................................56
聲 明 .........................................................................................................57
附錄 A 外文資料的調研閱讀報告(或書面翻譯) ..................................58


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