本實驗透過比較內部抽氣與無內部抽氣通道之間三項實驗數據：通道整體端壁紐賽數、凡寧摩擦係數及空氣熱性能係數，從而得知內部抽氣對於三通道熱傳強化影響。另於三個通道設置不同熱傳強化裝置，第一通道為平滑管壁、第二通道加上以直列擺放 45° 肋條、而第三通道則有附著-分離式交錯菱形柱鰭陣列。冷卻流體測試雷諾數在進口處為10000至30000，自第一通道流入後經過兩個轉彎處，於柱鰭陣列通道側壁面上排氣孔排出。內部抽氣孔設置於第二及第三通道隔板上，隔板兩面各開設九對水平方形小孔，用以導引第二通道肋條後方所產生近壁流至含有柱鰭陣列之第三通道。近壁流通過抽氣孔後顯著增強了無抽氣第三柱鰭通道密封頂蓋附近弱熱對流區域，從而產生具有區域性高熱傳紐賽數圖。沿著主流向下游觀察，壓力梯度會顯著降低，內部抽氣會顯著改善無抽氣通道空氣熱性能表現較差區域。內部抽氣影響下，第三柱鰭通道平均紐賽數和凡寧摩擦係數相對於無內部抽氣管道分別提高到0.44–0.68倍並減少到0.25–0.33倍。在內部抽氣對熱傳和壓降加乘效果下，空氣熱性能指標由無內部抽氣通道1.46-1.59大幅提升至內部抽氣通道3.04–4.24。為了在實務製作上能夠正確評估此種冷卻方法帶來效果，利用經驗公式推導區域平均紐賽數以及在具有和不具有內部抽氣三通道時各自凡寧摩擦係數。

By means of the comparative study between three sets of experimental data, namely the regional average endwall Nusselt number, Fanning friction factor and aerothermal performance indexes, detected from the test channels with and without the internal effusion, the impact of internal effusion on the performance of the heat transfer enhancement in the triple-pass cooling channel is disclosed. The first channel of each triple-pass test channel is smooth walled, whereas the in-lined 45° ribs and the staggered detached-attached pin-fin array are respectively deployed along the second and third channels. The range of Reynolds numbers at the entry of each test channel is 10,000-30,000. The coolant (dry-air) flows through the first 180° sharp bend from the entry smooth pass into the ribbed second pass and turns 90° in the elbow bend into the top-sealed pin-fin channel with lateral discharges from the exhaust holes through the sidewall of the pin-fin channel. There are nine internal effusion square-sectioned slots through the divider wall between the second and third passes to guide the adjacent-wall flows from the leeward side of the 45° ribs to the third pin-fin channel. The ejected adjacent-flows from the effusion slots significantly enhance the weak convective flow near the top sealed-end of the third pin-fin channel, leading to the regional high endwall Nusselt number in the pin-fin channel with the internal effusion. The streamwise pressure gradients from the entry of the second pass are also considerably reduced by the internal effusion. The aerothermal performances over the flow region with weak heat convection in the non-effusion channel are evidently improved by the internal effusion. Under the influence of internal effusion, the pin-fin channel average Nusselt number and friction factors were respectively increased to 0.44-0.68 times and decreased to 0.25-0.33 times of those without effusion channel. Acting by the synergistic effect of the internal effusion on heat-transfer and pressure-drop performances, the aerothermal performance indexes are considerably elevated from 1.46-1.59 in the non-effusion channel to 3.04-4.24. To evaluate the heat-transfer and pressure-drop augmentations of the present cooling method, the experimental data is correlated into the empirical correlations to calculate the regionally averaged Nusselt numbers and Fanning friction factors for the triple-pass channels with and without effusion for relevant industrial applications.

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