An Experimental Study of Heat Transfer and Effectiveness on the Endwall of a Vane Passage Using Paired Film Cooling Flow
張順富、吳佩學
E-mail: 9511167@mail.dyu.edu.tw
ABSTRACT
This research concerns about a new film cooling technique and the feasibility of its application to the protection of the endwall in a vane passage. This new technique utilizes pairs of coolant jets impinging against each other to form more aggregated and more uniform distribution of the film cooling effectiveness. The experimental results by using this technique are compared to those with parallel jets at the same coolant flow rate, endwall entrance condition, and the blowing ratio. In the experiments, the endwall of a vane passage was tested. Liquid crystal thermography was employed to measuring the distributions of local heat transfer coefficient
（HTC）and film cooling effectiveness. The Reynolds number of the main flow was fixed at . The blowing ratio was set be 0.5, 1.0, 2.0. The investigated entrance conditions include a smooth endwall, an endwall with a forward-facing entrance step, and an endwall with a backward-facing step. Results show that the pattern of the HTC distribution could be altered by the overall arrangement of the cooling holes. However, the HTC values did not change much. In the case of film cooling, the new technique with offset impinging cooling jets provides longer coverage area by the coolant, and the protected region is shifted towards the suction wall.
This new technique is less sensitive to the blowing ratio and the entrance condition of the endwall compared to the design with parallel coolant jets. Hence, it is a better technique.
Keywords : offset impinging cooling jets, endwall, film cooling effectiveness, liquid crystal thermography Table of Contents
封面內頁 簽名頁 授權書 iii 中文摘要 iv 英文摘要 v 誌謝 vi 目錄 vii 圖目錄 x 表目錄 xv 符號說明 xvi 第一章 緒論 1 1.1 前言 1 1.2 研究動機 2 1.3 研究目的 5 第二章 國內外相關研究 6 2.1 端壁區域三維流場 6 2.2 端壁區域熱傳與膜冷卻 10 第三章 研究 方法與進行的步驟 13 3.1 實驗系統與測試段 13 3.1.1 雙半葉片模型與測試段底板之設計 13 3.1.2 進口台階之設計 14 3.1.3 雙 半葉片模型側邊間隙大小之決定 15 3.2 實驗儀器校正 15 3.2.1 熱偶校正 15 3.2.2 Hot wire校正 16 3.2.3 風洞品質鑑定 18 3.2.4 風洞紊流強度場 19 3.2.5 液晶校正 20 3.3 數據化約基本理論 20 3.3.1 暫態液晶實驗求解熱傳係數 20 3.3.2 穩態液晶實 驗求解膜冷卻有效性 22 3.4 實驗條件與實驗程序 22 3.4.1 暫態熱傳液晶實驗條件與程序 22 3.4.2 穩態膜冷卻液晶實驗條件 與程序 23 3.5 影像擷取系統與影像處理程序 23 3.5.1 影像擷取系統 23 3.5.2 暫態液晶實驗影像處理程序 24 3.5.3 穩態液晶實 驗影像處理程序 24 3.6 數據化約流程 24 3.6.1 暫態液晶實驗數據化約流程 25 3.6.2 穩態液晶實驗數據化約流程 25 第四章 結 果與討論 26 4.1 端壁熱傳係數實驗結果 26 4.1.1 底板（一）熱傳係數實驗結果 26 4.1.2 底板（二）熱傳係數實驗結果 27 4.1.3 底板(一)與底板(二)熱傳係數之比較 28 4.2 端壁膜冷卻有效性實驗結果 29 4.2.1 底板（一）膜冷卻有效性實驗結果 30 4.2.2 底板（二）膜冷卻有效性實驗結果 32 4.2.3 底板(ㄧ)與底板(二)膜冷卻有效性之比較 34 第五章 結論 35 參考文獻 98 REFERENCES
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