隨著新一代有人或無人戰鬥機對高機動性、超遠程打擊和匿蹤等性能的要求不斷提高，將武器配置於內置彈艙已成為不可或缺的選擇。然而彈艙開啟時，常常因剪切層流入撞擊彈艙壁面產生較大的壓力梯度，此現象可能造成炸彈分離時出現俯仰角過大、急速滾轉等不安全情形。為了探討這一問題，本研究利用CFD (Computational Fluid Dynamics) 數值模擬的方式，模擬似X-47B於穿音速流場中進行投彈分離的動作，並分別於三種不同的位置使用噴流控制，以觀察剪切層受到干擾後對於投彈過程的影響。
本研究先使用一機翼下掛載炸彈進行驗證模擬，同時與文獻實驗數據比對，驗證結果顯示炸彈的姿態具有高準確度，因而增加了本研究數值模擬的可信度。此外，驗證模擬及研究項目均經過時間獨立性測試及網格獨立性測試之檢驗，以確保模擬結果的正確性。
研究結果顯示，在給予初始低頭力矩的情況下，三個位置的噴流控制均表現出抑制炸彈俯仰運動和降低壓力梯度的趨勢。其中，彈艙外前緣位置的噴流控制最終使得炸彈處於較低升力狀態，被認為是最適合的噴流控制位置。然而，在未提供初始低頭力矩的情況下，彈艙前壁和彈艙外前緣位置的噴流控制可能由於抬頭力矩和不對稱的渦流現象而使炸彈易於滾轉和偏航，從而影響到炸彈尾翼提供低頭力矩的功能，因此不建議在此情況下使用噴流控制。另外，增加噴流速度並不一定能提高安全性，在彈艙內前緣處使用噴流控制時會降低安全效果。因此，增加噴流速度需要仔細評估成本和效益。最後，不同的彈射條件對於最佳的噴流位置可能不同，受到複雜物理現象的影響，這體現了解決本問題需要全面考慮不同條件下的物理現象和噴流控制策略。

As the demands for high maneuverability, extended-range strikes, and stealth capabilities increase in the new generation of manned or unmanned fighter aircraft, the integration of weapons into internal weapon bays has become an indispensable choice. However, when the weapon bay is opened, the collision of the shear layer flow with the interior surfaces of the bay often leads to significant pressure gradients, which can cause unsafe conditions during bomb separation, such as excessive pitch angles and rapid rolling. To investigate this issue, this study utilizes Computational Fluid Dynamics (CFD) numerical simulations to model the bomb separation process in a transonic flow similar to that experienced by an X-47B aircraft. Additionally, three different positions of jet control are employed to observe the impact of disturbed shear layers on the bomb ejection process.

This study first conducted verification simulations using a wing-mounted bomb and compared the results with experimental data from the literature. The verification results demonstrated high accuracy in predicting the bomb's attitude, thereby increasing the credibility of the numerical simulations in this study. Additionally, both the verification simulations and the research project underwent tests for time independence and grid independence to ensure the accuracy of the simulation results.

The research results indicate that, under the condition of providing an initial nose-down moment, jet control at all three positions shows a tendency to suppress the bomb's pitch motion and reduce pressure gradients. Among them, the jet control at the external leading edge of the weapon bay eventually places the bomb in a lower lift state, making it the most suitable jet control position. However, when no initial nose-down moment is provided, jet control at the front wall of the weapon bay and the external leading edge of the bay may lead to roll and yaw tendencies due to the nose-up moment and asymmetrical vortex phenomena. This could interfere with the function of the bomb's tail wing providing a nose-down moment, making jet control not recommended under such circumstances. Furthermore, increasing jet velocity may not necessarily enhance safety, and using jet control at the inner leading edge of the weapon bay could reduce safety effectiveness. Therefore, the decision to increase jet velocity requires careful cost-benefit analysis. Lastly, optimal jet control positions may vary under different ejection conditions, influenced by complex physical phenomena. This underscores the need for a comprehensive consideration of various physical phenomena and jet control strategies to address this issue effectively.

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