相控阵机载预警雷达对悬停直升机的探测

本文研究相控阵机载预警(AEW)雷达针对旋翼回波信号特点的检测技术,提出了采用时-空级联自适应处理(TSA)杂波抑制结合多多普勒通道联合检测的方法,并导出了具有恒虚警率(CFAR)特性的检测器结构.理论分析和仿真实验证明了这种检测器的可行性和有效性.     

Influence of Wall Effect on Comprehensive Controllability for Ducted Fan Aircraft

A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes. The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model. Based on the duct test bench experiment and computational fluid dynamics (CFD) simulation analysis, the expressions between the different distances $d_{\rm{WE}} $ from the rotor center of the prototype to the wall and the thrust, reaction torque, and tilting moment of the system under hovering conditions are obtained. The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance $d_{\rm{WE}} $ and the comprehensive controllability of the system. The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance $d_{\rm{WE}} $, and only the controllability vector of the rolling channel increases significantly. At the same time, the tilting moment also increases significantly, which strengthens the tendency of the prototype to tilt towards the wall.     

固定时间稳定航天器相对轨道悬停控制

针对航天器相对空间目标的定点悬停控制需求,基于非线性反馈固定时间稳定算法设计了一种闭环悬停控制律.阐述了固定时间稳定的原理,以C-W方程为相对运动模型设计了悬停控制律,可以通过改变相关控制参数来消除初始悬停误差和干扰的影响,实现对控制效果的调节.结果分析表明,提出的控制律对初始悬停误差收敛速率较快,能够保持长时间、高精度定点悬停,仿真结果验证了方法的有效性.     

悬停直升机的匹配检测

详细分析了悬停直升机旋翼回波的特性，提出了一种多目标假设与匹配检验相结合的悬停直升机检测新算法。理论推导和仿真实验表明：该算法在信噪比较低的情况下依然有效。     

悬浮式声诱饵和悬浮式深弹阵协同对抗声自导鱼雷建模与仿真

舰艇如何优化布放悬浮式声诱饵和悬浮式深弹阵防御声自导鱼雷是舰艇防御鱼雷攻击的重要问题之一。本文建立了舰艇使用悬浮式声诱饵与悬浮式深弹阵对抗鱼雷的作战模型,采用极值法和非线性规划方法,确定了悬浮式声诱饵与悬浮式深弹阵的发射策略及舰艇的规避航向,使舰艇布放悬浮式声诱饵与悬浮式深弹阵和正确的规避机动有效结合,以期达到对抗来袭鱼雷的最佳效果。仿真结果表明,采用本文方法可以达到软硬防御手段有效结合对抗来袭鱼雷的双重效果,鱼雷拦截概率提高了10%～30%。     

火箭助飞式声干扰器和悬浮式深弹协同对抗线导鱼雷建模与仿真

提出了使用火箭助飞式声干扰器和悬浮式深弹组合协同防御潜射线导鱼雷战术,根据线导鱼雷射击原理,仿真估算了导引艇的舷角,建立了火箭助飞式声干扰器和悬浮式深弹这一软硬反鱼雷武器组合协同防御潜射线导鱼雷的数学模型,利用运筹学中的优化方法确定了两型武器的布放策略及舰艇的规避航向,并对使用软硬武器协同对抗与单一软对抗的对抗成功概率进行了仿真比较,结果表明,使用软硬武器协同对抗效果显著,较单一使用软对抗线导鱼雷的成功概率提高了20%~36%。     

反潜直升机吊声搜潜悬停探测飞行模型

针对反潜直升机使用吊声搜潜时需悬停探测的问题,基于反潜直升机悬停探测飞行过程、最短飞行路径准则和几何原理,规划反潜直升机悬停探测飞行路径,并考虑风对反潜直升机飞行状态的影响。对建立的飞行路径进行了数学求解与分析,最终给出悬停探测飞行数学模型。根据建立的悬停探测飞行数学模型,对单机圆形应召搜潜的飞行路径进行仿真验证,仿真结果表明,悬停探测飞行数学模型可以更加真实地模拟反潜直升机吊声搜潜的实际飞行路径。     

直升机悬停双雷齐射初探

针对直升机投雷一般采用单雷射击的现状,提出了采用直升机悬停双雷齐射的方法。通过对双雷齐射搜索面的组织、目标可能位置区域、齐射射击瞄准点的选取以及潜艇规避机动模型的分析,建立了潜艇纯机动规避情况下鱼雷命中概率仿真模型。仿真结果表明,与单雷射击相比,双雷齐射可有效提高对目标的发现概率,并能弥补单雷射击在大舷角时命中概率较低的不足,在相同发现概率条件下双雷齐射对目标的射击距离更远。     

On the quasi-steady aerodynamics of normal hovering flight part II: model implementation and evaluation

This paper introduces a generic, transparent and compact model for the evaluation of the aerodynamic performance of insect-like flapping wings in hovering flight. The model is generic in that it can be applied to wings of arbitrary morphology and kinematics without the use of experimental data, is transparent in that the aerodynamic components of the model are linked directly to morphology and kinematics via physical relationships and is compact in the sense that it can be efficiently evaluated for use within a design optimization environment. An important aspect of the model is the method by which translational force coefficients for the aerodynamic model are obtained from first principles; however important insights are also provided for the morphological and kinematic treatments that improve the clarity and efficiency of the overall model. A thorough analysis of the leading-edge suction analogy model is provided and comparison of the aerodynamic model with results from application of the leading-edge suction analogy shows good agreement. The full model is evaluated against experimental data for revolving wings and good agreement is obtained for lift and drag up to 90° incidence. Comparison of the model output with data from computational fluid dynamics studies on a range of different insect species also shows good agreement with predicted weight support ratio and specific power. The validated model is used to evaluate the relative impact of different contributors to the induced power factor for the hoverfly and fruitfly. It is shown that the assumption of an ideal induced power factor (k = 1) for a normal hovering hoverfly leads to a 23% overestimation of the generated force owing to flapping.     

小型无人直升机纵横角动态耦合辨识建模

针对小型无人直升机耦合建模问题提出了一种频域解耦辨识建模方法,该方法通过处理针对耦合辨识的实验数据得到指定频域范围内被辨识耦合的频域特性,对频域特性进行拟合从而获得耦合模型.提出了适用于多输入输出(MIMO)系统的频域特性计算方法,定义了一种复合相干函数并证明其能够用于表达在耦合通道辨识中输入输出的相关性.基于该方法,对一种小型无人直升机在悬停状态的纵横角动态耦合模型进行了辨识,并将耦合模型加入到直升机仿真模型中考察其对模型预测精度的影响.模型预测输出与实际输出的比较表明,相较于普通模型,考虑了耦合动态的仿真模型能够更为精确地预测实际输出.