應用定常液晶測溫技術於噴流衝擊陣列熱傳增益研究第一部份：噴流傾斜角度與表面粗糙度的影響

Application of Steady-State Liquid Crystal Thermometry to Jet Impingement Cooling Array Heat Transfer Study Part Ⅰ: Effects of Jet Incline Angle and Surface Roughness

10.6124/TAASRC.200512_37(4).06

劉通敏(Tong-Miin Liou)；田維欣(Wei-Hsin Tien)

噴流衝擊 ； 液晶測溫技術 ； 噴射推進 ； 渦輪機 ； Jet impingement ； Liquid crystal thermometry ； Jet propulsion ； Gas turbine

中國航空太空學會學刊

37卷4期（2005 / 12 / 01）

333 - 340

繁體中文

本研究利用定常液晶測溫技術(Steady-State Liquid Crystal Thermometry)量測散熱面受陣列噴流的熱傳。實驗探討陣列噴流的傾斜角度Ө與散熱面的粗糙度對噴流衝擊表面熱傳的影響，此一研究未見於先前文獻報導。實驗之雷諾數範圍爲1200~9200，Ө角爲30度與90度。實驗結果首先與公開文獻之平滑散熱面結果比較驗證，獲致合理的一致性，並提供90度噴流／平滑面之組合較30度噴流／平滑面之組合熱傳增益較佳之物性解釋。結果亦發現粗糙的被衝擊面會對下游的熱傳分佈有所助益，其效果會隨弦向向下游遞增，可增加至同位置平滑面區域平均紐賽數的150%。

Heat transfer characteristics of jet impingement cooling array were studied using the steady-state liquid crystal thermometry. The parameters examined are jet inclined angle (Ө=30-deg and 90-deg), cooling surfacecondition (smooth vs. roughened) and Reynolds number (Re=1200 to 9200). Among these parameters the effects Ө/roughened surface have not been reported. For the smooth cooling surface the correlation of Nusselt number (Nu) versus Re is found to be in reasonable agreement with the reported trend. Physical mechanism is provided to explain the superiority of heat transfer augmentation attained by the 90-deg/smooth surface over the 30-deg/smooth surface. Heat transfer is enhanced by roughening the cooling surface. The enhancement increases with increasing downstream distance and attains a maximum enhancement of Nu/roughened surface=150% Nu/smooth surface.