共查询到19条相似文献,搜索用时 171 毫秒
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张洪 《中国民航学院学报》1992,10(3):18-23
本文基于文献[1]-[4]对大型喷气飞机穿越严重风切变-微下冲气流的大量的优化轨迹的分析所得出的结论,提出了一种简单、近似的飞机安全穿越微下冲气流的性能指标,并基于能量守恒定律推导出一种近似的计算飞机抗拒风切变能力的解析公式。通过对波音-727飞机在起飞、着陆阶段的抗拒风切变能力的计算,表明该公式之计算结果与通过时间历程进行动态分析计算所得结果一致。从而为飞机风切变的警告,抗风切变控制系统的设计等等提供了一个有效的计算方法。 相似文献
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本文对大型喷气飞机穿越严重风切变——微下冲气流提出了一种简单、近似的飞机安全穿越微下冲气流的性能指标,并基于能量守恒定律,推导出一种近似的计算飞机抗拒风切变能力的解析式。通过对波音-727飞机在起飞、着陆阶段的抗风切变能力的计算,表明该式之结果与通过时间历程进行动态计算所得的结果是一致的,从而为飞机风切变的告警以及抗风切变控制系统的设计提供了一个参考的准则。 相似文献
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本文利用风切变场中飞机的近似的能量高度传递函数和激发飞机长周期振荡的最严重的风切变模型,研究并确定了适用于机载风切变系统的风切变危险通报(caution)的阀值.为机载风切变探测告警系统的研制提供了风切变的危险性评估准则. 相似文献
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本文把烟气流作为一种人为的风切变场,分析和计算了烟气流的抬升夹卷模式,讨论了飞机对称穿越烟气流场时的响应。可为电厂和机场的相关设计提供参考依据。 相似文献
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一、引言
低空风切变是飞机起飞降落阶段威胁飞行安全的危险因素。低空风切变有时间短、尺度小、强度大、发生突然的特点。由于大、中型喷气运输机质量很大,具有很大惯性,发动机加速性能羞,在低高度往往缺乏足够的空间进行应对,在遭遇风切变的情况下,由于风向、风速和飞机空速的内在联系,风切变会对飞机空速造成影响,进而造成飞机的升力变化,使飞行高度发生变化,对飞行高度低、速度小的起飞进近飞机危害是极大的。所以,对飞行员来讲,深刻了解风切变对飞行的影响,加强对低空风切变判断和防范的研究,是十分重要的。飞行员应尽量提早发现风切变,一旦陷入其中,应能正确处置,安全脱离。 相似文献
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飞机在大气中飞行时,会受到复杂的大气紊流的影响,其中以风切变最为普遍。文章分别对有风切变影响和无风切变影响下飞行的飞机建立纵向运动方程,并根据小扰动线性理论,针对低空定常平飞,分析了各自的纵向运动模态特性,为飞机飞行控制研究提供一定的理论依据。 相似文献
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本文给出一种处理线性系统降阶的集结方法,并根据该方法将飞机纵向运动方程和横侧向运动方程进行降阶分解,得到了飞机的沉浮、短周期、滚转-螺旋和荷兰滚运动模态的各近似式,结果表明本文中的各近似式精度较好,特别是提高了沉浮及荷兰滚阻尼的估计精度。 相似文献
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《中国航空学报》2020,33(1):191-204
To efficiently and fully utilize aircraft carrier resources, an optimization model is presented to deal with parameter matching between aircraft and carrier in the process of aircraft catapult launch. Based on carrier aircraft longitudinal dynamic equations and theorem of kinetic energy in catapult launch course, the work characteristics of different forces are learned and a theory model of parameter matching is deduced. In view of the uncertainty of the model parameters of the theory model and the low matching accuracy of the approximate model, an optimization model of parameter matching is introduced in line with the structure of theory model and the approximate model and is generated by the proposed immune genetic algorithm. Compared with the original genetic algorithm and immune algorithm, the proposed algorithm has better calculation accuracy and convergence. The calculation results show that the optimization model occupies certain application value of engineering estimation from the comparison with the relevant literature data and has higher precision than the approximate models. The validity of the proposed approach is verified with numerical case study on a carrier based aircraft. 相似文献
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飞机总能量控制系统的研究Ⅰ——原理分析与系统设计 总被引:1,自引:0,他引:1
飞机总能量控制是一种全新的综合飞行/推力控制技术,从控制飞机总能量的变化与分配出发,全面解决纵向飞行轨迹控制与速度控制之间的耦合问题;进而建立起一体化的综合飞行控制系统。用多变量系统解耦控制理论研究了这种控制系统,首先分析了总能量控制的基本思想,建立起包含飞机纵向姿态控制回路和发动机推力控制回路的飞机质点能量运动模型,然后利用输出反馈和V规范型前馈解耦策略,对此系统进行解耦分析,设计出能实现飞行轨迹与速度间解耦控制的总能量控制律,并确定出系统的设计条件;最后以波音(Boeing)707飞机为对象,进行了具体的系统设计。 相似文献
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《中国航空学报》2023,36(2):58-75
A four-cable mount system is proposed for full-model wind tunnel flutter tests, which may adjust the pitch and roll attitude of the aircraft scaled model and ensure that the model is not subjected to cable tension. The system provides sufficient support to simulate the free flight of the aircraft by applying appropriate spring stiffness and cable tensions. The proposed four-cable mount system is modeled based on Lagrange mechanics, and its dynamics equations consider aerodynamic effects. The singularity of the system and its bifurcation characteristics under flow conditions are analysed to determine the supercritical bifurcation phenomenon for different tension levels and distances from the front suspension point to the mass centre of the model. The mathematical expressions of the longitudinal flight stability of the cable mount system are derived by linearising the system dynamics equations using small perturbations. The influence of the cable tension, spring stiffness, suspension point position, and other factors on the flight stability of the aircraft are analysed. A feedforward control algorithm is proposed to minimize the total elastic potential energy of the system. The results show that the model is in the level flight state when the elastic potential energy of the four-cable mount system is minimized. A feedback control design method is proposed based on the Lyapunov stability theory to derive the closed-loop stability conditions. The system dynamics model that includes the aircraft rigid body model, flexible cables, pulleys, springs, aerodynamic model, and servo motor control is established using the flexible multibody dynamics method. A multibody dynamics solver and Simulink are used to simulate the attitude adjustment of the model in the wind tunnel and verify the supercritical bifurcation characteristics of the system and the effectiveness of the feedback and feedforward control. 相似文献
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共面变速拦截对策的一个统一的近似反馈解 总被引:1,自引:0,他引:1
本文运用微分对策理论研究了战术导弹与目标飞机之间的共面变速拦截问题,采用强迫奇异摄动方法求得了统一的近似反馈制导控制规律。选用实际空气动力数据的算例表明这个次最优制导控制规律是有效的。 相似文献
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The robust trajectory control of a class of nonlinear systems which can be decoupled by state-variable feedback is considered. It is assumed that the system matrices are unknown but bounded. A nonlinear control law is derived so that the tracking error in the closed-loop system is uniformly bounded and tends to a certain small neighborhood of the origin. The error dynamics are asymptotically decoupled in an approximate sense. The controller includes a reference trajectory generator and uses the integral feedback of the tracking error. On the basis of this result, a flight control system is designed for the control of roll angle, angle of attack, and sideslip in rapid, nonlinear maneuvers of aircraft. Simulation results are presented to show that large, simultaneous lateral and longitudinal maneuvers can be performed in spite of the uncertainty in the stability derivatives 相似文献
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根据机动中机翼摇晃的主要动态特性,建立了多维非线性模型;在动态逆控制律的设计中,特别针对外环中状态变量多于操纵舵的问题,构造了基于加权最小二乘逆的控制结构,并引人积分反馈以弥补最小二乘近似逆及模型不确定性等因素导致的系统逆误差.仿真实验结果表明,所设计的加权最小二乘逆控制器,不仅能确保战机准确地跟踪机动指令,更能有效地... 相似文献
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Approximate Nonlinear Modeling of Aircraft Engine Surge Margin Based on Equilibrium Manifold Expansion 总被引:1,自引:1,他引:1
Stable operation of aircraft engine compressions is constrained by rotating surge. In this paper, an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is presented. Firstly, this paper gives an overview of the current state of modeling aerodynamic flow instabilities in engine compressors. Secondly, the expansion form of equilibrium manifold is introduced, and the choosing scheduling variable method is discussed. Then, this paper also gives the identification procedure of modeling the approximate nonlinear model. Finally, the modeling and simulations with high pressure (HP) compressor surge margin of the aircraft engine show that this real-time model has the same accuracy with the thermodynamic model, but has simpler structure and shorter computation time. 相似文献