- 學位論文
機翼釋放具鰭片彈體翻滾、俯仰和偏航率紊流模擬
Turbulent Simulations of Rolling, Pitching and Yawing Rates of a Store with Fins Released from a Wing
摘要
在飛機與彈體進行分離時，將彈體順利地擊中目標物雖然重要，但如果所釋放之彈體撞擊到母體本身而導致損壞這並不是我們想看到的，所以能將彈體順利分離也是值得關注的一環，本文應用ESI CFD FASTRAN 商用軟體研究紊流通過機翼釋放具鰭片彈體之參數效應，在卡式座標系統下求解三維非穩態Navier-Stokes方程式及k-ε紊流模式，採用雙區塊Chimera網格系統，不同區塊網格系統重疊部分相互自動傳遞資訊，為驗證本文計算的正確性，彈體重心瞬間軌跡與翻滾、俯仰、偏航角度、瞬間速度、角速度計算結果與實驗值比較後，趨勢分佈非常接近，並改變流場馬赫數、前後施力同時倍增、僅前施力倍增與飛行攻角等四種參數值以探討分離彈體非穩態物理現象。馬赫數增加時，彈體俯仰角最大值出現時間增快且俯仰角隨馬赫數增加而降低，偏航角則增加;俯仰率最大值遞減，而偏航率最大值出現時間則提前。
並列摘要
As for the release of store from the aircraft, it is important that the target is hit and destroyed by the stores. However, it will not be allowed and expected if the mother aircraft is hit and damaged by the store it releases. Consequently, smooth separation of store and aircraft is also concerned. In this article, ESI CFD FASTRAN is the commercial software applied to study the parametric effects of turbulent flows around a store with fins released from a wing. The three-dimensional, unsteady Navier-Stokes equations and k-ε turbulent model are solved in the Cartesian coordinate system. The Chimera two-block grid system is utilized, and grid communication among two blocks are automatically implemented. To evaluate the accuracy of the present calculation, the calculated instantaneous trajectory of center of gravity of store, angles of roll, pitch and yaw, velocity and angular rate are compared with those of experimental data. The satisfactory agreement is achieved. Then, computations of different values of Mach number, both forward and rearward forces applied on the store, single forward force applied on the store, and angle of attack are carried out to investigate the unsteady physical phenomena of separated store. The angle of pitch of store will be reduced and time of maximum angle of pitch will be shortened if Mach number is increased. Meanwhile, angle of yaw will be enlarged and maximum value of pitching rate will be decreased. Time of maximum yawing rate will be shortened as well.