新一代戰鬥機如美軍F-35使用三維向量噴嘴可提高飛行表現的機動性及靈敏性，但是也衍生出許多設計上的困難，如耐高溫材料之研發或冷卻系統的設計。向量噴嘴之高實驗成本以及高溫高速流體導致實驗的量測困難，本研究之三維向量噴嘴流場模擬，可以做為三維向量噴嘴冷卻效能的重要評估。本研究之數值模擬使用商用CFD軟體ANASYS FLUENT並採用SST k-ω紊流模式，此外成功地建立薄膜冷卻系統，且完成出口推力變化之分析，另外進行三組不同參數的模擬。首先，原本所預期最高溫區域位於偏轉段上部，但經由模擬分析顯示，有對外熱傳情況下偏轉段上部有較大散熱面積，所以噴嘴最高溫位置發生於偏轉段內側接近第二漸縮段的位置。過小流量之冷卻流體，會因為偏轉過程中造成的偏轉段上壁面高壓導致冷卻流體無法順利注入。冷卻流量比例較大者，向量噴嘴壁面可獲得較多的冷卻空氣覆蓋，最高溫區域的溫度下降率也比較高。冷卻流量大時對於主流場的衝擊也較大，推力損失的比例也比較多。而當冷卻流體注入角度與主流場越接近垂直時，冷卻流體對於主流場的衝擊也較大，進而影響推力表現。注入孔隙大小會影響注入口上下方冷卻流量之比例，進而影響冷卻效果的優劣。另外噴嘴冷卻流道的幾何外型設計是冷卻效能或推力效能優劣的主要關鍵。

Modern fighters, such as USAF F-35, use 3D thrust-vectoring nozzles to enhance maneuverability and flexibility. Although the design improves fighter maneuverability, it causes thermal problem due to high-temperature flow strike. The internal flows of a 3D thrust-vectoring nozzle are analyzed in this study through numerical simulation. The characteristics that this research concerned include the thrust of the nozzle, the maximum wall temperature, and the detail flow in the cooling channel. In order to improve cooling benefit, three sensitive parameters, such as cooling mass flow rate of main flow, angle of cooling air injection, and slot length of cooling air injection, are analyzed. In the present study, the commercial CFD software, ANSYS FLUENT, employing the SST k-ω turbulence model and DO radiation model, was applied to analyzing the nozzle thrust variations. The simulation results of previous studies indicated that high temperature flow impacted the upper deflection wall. But surprisingly, this study indicates that upper deflection wall temperature is not as originally expected to be higher than the lower one. This is because the deflection section can deploy such that the upper wall has more cooling area for cooling down the nozzle wall. According to this reason, we need to concentrate cooling effect on the lower deflection wall. First, when the 3D thrust-vectoring nozzle deflects to 90 degree, the higher pressure at deflection upper area will cause lower quantity of cooling air injected to the main flow smoothly. Rich quantity of cooling air interacts intensely with the main flow, causing the thrust loss. Second, cooling-air injection angle is a main factor. If the channel direction is more vertical between the main flow and the cooling air, it will affect the thrust performance strongly. Due to the cooling channel geometry, the tilt angle model causes more heat transfer through the inner wall. Third, cooling injection slot length influences the cooling-air injection quantity of the upper site and the lower site when the 3D thrust-vectoring nozzle deflects to 90 degree. It will affect the temperature decreasing rate of high temperature decreasing rate temperature area seriously. Therefore, the cooling channel geometry design is a major factor for cooling effect and thrust performance.

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