【作者】 何烈堂；

【导师】 周伯昭； 侯中喜；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2008， 博士

【摘要】 本文基于乘波构型优化设计了跨大气层飞行器的基本气动外形,分析了其气动力和气动热特性,建立了跨大气层飞行的三自由度飞行动力学模型并进行了弹道仿真,采用提出的分段优化法、改进的极大值原理进行了最大射程弹道优化设计,开展了跨大气层飞行器的力热环境分析与飞行规划研究。主要研究内容和所得结论如下:从多个角度开展了跨大气层飞行器的气动布局选型研究,得出乘波体构型是其理想气动布局。建立了乘波体气动布局设计模型,改进了基于NSGA-II的多目标遗传算法,利用该改进遗传算法对乘波体进行了优化设计,得到升阻比和容积效率综合性能较为理想的飞行器基本外形。利用CFD手段,分析了该设计基本外形的流场特性,计算和拟合了该飞行器的气动参数。设计了一个基于该外形的气动力风洞实验,实验得到的气动数据与CFD计算结果相比,在小攻角范围二者的升阻比基本是一致的。建立了基于乘波构型的气动热计算模型,用数值模拟法与该气动热工程估算方法进行了对比研究,结果表明该方法是可行的。结合跨大气层飞行弹道,基于该气动热计算模型开展了跨大气层飞行全弹道的力热环境分析,所得结果对跨大气层飞行器的气动防热和弹道的综合优化设计具有重要的参考价值。建立了跨大气层飞行器三自由度的飞行动力学模型,以最大升阻比飞行弹道为基准弹道,进行了弹道仿真。分析了关机点参数和气动参数对弹道参数的影响规律,探索了不同控制方式下跨大气层飞行的弹道特性,与惯性弹道进行了对比研究,得知跨大气层飞行弹道在飞行性能和突防性能方面具有得天独厚的优势。从飞行力学原理、能量解析、工程实现等角度综合分析了无动力跨大气层飞行的可行性。所得结论对跳跃飞行能否成为又一重要机动突防手段提供了参考依据。通过对跃滑弹道的分段研究,提出了一种适于跃滑弹道最佳航迹优化的新方法——分段优化法。该方法不仅只要最佳程序攻角容差设置得足够小,优化时间取得足够短,迭代次数进行得足够多,就一定能够得到真正物理意义上的射程最大弹道,而且可以避免应用极大值原理优化时所碰到的初值敏感问题,也不会出现极大值原理优化经常出现的局部最优解现象。建立了极大值原理在三自由度高超声速跃滑弹道优化中应用的数学模型,推导了考虑地球旋转和扁率影响的三自由度状态方程右函数的偏导数。本文应用遗传算法和单纯形下山法的组合方法解决了极大值原理中的初值灵敏度大问题;同时去除终端自由的约束条件,转而直接对优化目标进行优化,成功解决了需同时满足六个终端条件的问题。优化方法的改进进一步提高了极大值原理的实用价值,拓宽了其应用范围。通过对各种跨大气层飞行控制方式的对比研究和射程最大弹道的优化,得出了射程最大的最佳控制方式是最大升阻比滑翔飞行的结论,并采用灵敏度分析方法对其进行了验证。提出了最大升阻比滑翔飞行的边界条件,使用弹道仿真、理论解析两种方法进行了证明,该结论对跳跃滑翔式跨大气层飞行或其他机动飞行的弹道设计具有重要的参考价值。基于跨大气层飞行器的受力、受热和射程进行了多目标弹道优化设计,在力热环境分析和多目标弹道优化设计的基础上,根据跨大气层飞行的特点,展开了飞行走廊边界约束条件的分析,并确定出飞行走廊。探讨了关机点参数对飞行走廊约束条件各参考量的影响,给出了飞行走廊内的关机点参数值域。最后开展了基于各约束边界条件下跨大气层飞行弹道的飞行规划研究。结果表明,文中所用飞行规划方法对跨大气层飞行弹道具有较好的优化设计效果,该方法对其它飞行器的弹道优化设计也具有一定借鉴意义。本文的研究成果对跨大气层飞行器的总体设计以及飞行规划具有重要的参考价值,所提出的方法及分析结论将为跨大气层飞行器气动防热和弹道综合优化设计提供分析与论证方法。更多还原

【Abstract】 A basic aerodynamic shape for trans-atmospheric vehicle was optimized based on waverider configuration, the three-dimensional flight dynamics model was constructed for trajectory simulation, maximum-range trajectory was optimized with the new put forwarded subsection optimization method and the improved maximum principle in this dissertation, the force and heat environment of trans-atmospheric vehicle was analyzed, flight planning was researched. The main work and achievements are summarized as follows:Trans-atmospheric vehicle configuration was studied from many aspects and waverider was proved to be the idealist one. The design model of waverider configuration was founded, which was optimized with the improved multi-object optimum genetic algorithm based on NSGA-II, and relatively better basic shape for trans-atmospheric vehicle with high volumetric efficiency and lift to drag ratio was obtained. Flow Fields of the aircraft was analyzed with CFD method, the aerodynamic coefficient was calculated and curve fitted. A wind tunnel experiment was designed and the lift to drag ratio agreed well with CFD results in small region angle of attack.The aerodynamic heat model was established, which was verified by CFD result. Combined with the trajectory, the force and heat environment during the trans-atmospheric flight was studied and the conclusions had instructed significance for aerodynamic heat-resist and trajectory synthesized optimization.The three-dimensional flight dynamics model was set up and the simulation that based on the maximum lift to drag ratio was chosed as the basic trajectory. The change law of trajectory parameters with the parameters of the shut-down point and aerodynamic coefficient were analyzed; the characteristic of several types of skipping and gliding trans-atmospheric trajectory was investigated, which showed that the trans-atmospheric trajectory has the advantage in penetration and flight performance comparing with the inertia trajectory. The feasibility of trans-atmospheric flight was confirmed by the following three aspects: the theory of flight dynamic, energy analytic and engineering realization. It shows that the trans-atmospheric flight could be another maneuver penetration means and can be referenced in future new type of weapon equipment.The subsection optimization method was put forward for trans-atmospheric flight trajectory optimization. The method did not have the sensitivity problem of initial value, and its optimum result approaches to the real maximum range trajectory infinitely as long as the subsection step is small enough and the iterative number is big enough. It is an availability method for long-range trajectory optimization both in theory and in practicality effect. The maximum principle model applied to three-dimensional trans-atmospheric trajectory optimization was established, the partial derivative of the right function was deducted considering earth circumrotate and flat ratio. The key point applying the maximum principle is the solution of two-point boundary value problem. Because of the long integral time corresponding to the long distance hypersonic skipping-gliding flight, the maximum principle is sensitive to initial values of state variables. Moreover, the traditional maximum principle needs to satisfy six rigorous terminal constraints simultaneously to simulate three-dimensional trajectory. The way combining the genetic algorithm and the downhill simplex method can solve the above two questions. The improved method gives more practicality of the maximum principle in optimum control field.Comparing and researching many kinds of flight scheme of maximum range in skipping-gliding trajectory, it is found that gliding at maximum lift to drag ratio is the best one, and it is certified by sensitivity analysis methods. Then the boundary condition of gliding at maximum lift to drag ratio was proposed, proved with trajectory simulation and theory analytical methods. The conclusion has consequence in optimum design of skipping-gliding flight or other maneuver trajectory.The trajectory was optimized with multi-object including force, heat and range. Based on the trajectory environment analysis and multi-object optimization, the restriction boundary of flight corridor was studied and determined. The shut-down parameters’effect to the flight corridor was analyzed and its numerical region in flight corridor was obtained. Considering all the restriction of flight corridor boundary, the flight planning of trans-atmospheric vehicle was researched.The achievements obtained in this dissertation provide an important guidance to integrated design of trans-atmospheric vehicle and flight planning research. The methods and conclusions can provide analysis and demonstrating methods for aerodynamic heat-resist and trajectory synthesized optimization。更多还原