重装空投中出舱速度对货物翻转的影响分析

为了明确出舱速度对货物翻转的影响程度,构建了货物翻转运动轨迹模型,并通过实例在不同出舱速度的条件下对货物最大翻转角进行计算分析,拟合出货物翻转角随出舱速度的变化曲线,实现了货物出舱速度对货物最大翻转角影响的状态可视化。该计算模型可为控制合理的出舱速度范围以提升飞机空投安全提供参考。     

美国海军直升机装备转型的几个特点

基于美海军战略调整对舰载直升机装备的影响,分析了美海军舰载直升机装备转型的主要特点,对多用途舰载直升机、重型直升机、舰载无人直升机等装备的技术特征进行了剖析。从建设海洋强国战略的角度,提出了我国舰载直升机装备发展的对策建议。     

微小型无人直升机姿态信号的互补滤波融合算法

基于惯性测量技术获取飞行器姿态信号的方法已被广泛应用,然而对于微小型或低成本无人飞行器而言,通过MEMS传感器获取满足精度要求且稳定可靠的姿态信号仍然是具有一定难度的工程问题。文章针对民用微小型无人直升机的低成本要求和使用环境,利用三轴角速率陀螺仪和加速度计在姿态估计中频率互补的特性,采用互补滤波算法,改进了滤波参数的自适应调整方法,实现了俯仰角和滚转角信号的有效融合,得到的姿态信息可用于微小型无人直升机的内环增稳控制。仿真和试验数据表明,该方法测量精度较高,工程实现简单,算法稳定,能有效解决微小型无人直升机姿态信号的工程求解和使用问题。     

高精度A/D转换技术在惯导系统中的应用研究

针对惯导系统对模数转换电路的使用要求,明确了制约A/D转换电路在惯导系统中应用的瓶颈是零位稳定性,分析了A/D转换电路零位的影响因素,提出了解决方法。并设计出一款A/D转换电路,该电路的测试结果表明解决方法有效,可将零位提高2个数量级,与传统V/F转换电路相当。证明采用A/D转换芯片的模数转换电路能够满足惯导系统的精度要求,同时相比V/F、I/F具有高采样率和高分辨率的优势,技术指标可以满足高精度加速度测量系统等实际工程需求。     

发动机谐振与箭体模态耦合稳定性及机理研究

针对发动机谐振可能与箭体弹性振动之间发生耦合共振,从而引起姿态控制系统不稳定的问题,首先将发动机谐振特性简化为一个二阶环节,建立了包含发动机谐振方程的火箭姿态动力学模型;然后分析了发动机谐振对箭体模态极点频率和阻尼比的影响,并从理论上分析了出现负阻尼比时发动机和箭体模态间的耦合共振机理,在此基础上计算了导致姿态控制系统...     

某超高速转子系统减振结构研究

为解决某超高速转子系统的失稳碰摩问题,以干摩擦阻尼耗散转子涡动能量理论为依据,采用一种自由安装式干摩擦片减振结构(干摩擦阻尼器).该结构在转轴上安装波形弹性垫片及干摩擦片,通过螺母预紧力矩向波形弹性垫片及各干摩擦片提供轴向正压力.干摩擦片随转子振动并产生相对运动,从而耗散转子涡动能量,达到减振、增强转子稳定性的目的.通...     

Numerical Simulation of 2D Supersonic Magnetohydrodynamic Channel and Study on Hall Effect

In this research effort,numerical simulation of two-dimensional magnetohydrodynamic(MHD) channel is performed and Hall effect is studied.The computational model consists of the Navier-Stokes(N-S) equations coupled with electrical-magnetic source terms,Maxwell equations and the generalized Ohm’s law.Boundary conditions for the electrical potential equation considering Hall effect are derived.To start with,the MHD channel with single-pair electrodes is studied and flow of the electric current is in accordance with physical principle.Then the MHD channel with five-pair electrodes is numerically simulated.The results show that the electrical current concentrates on the downstream of the anode and the upstream of the cathode due to Hall effect,and the flow field becomes asymmetrical.At the current value of the magnetic interaction parameter,the electrical-magnetic force affects the flow remarkably,decreasing the outlet Mach number and increasing the outlet pressure;what’s more,the flow structure in the channel becomes extremely complex.Performances of MHD channels with continual electrodes and segmented electrodes are compared.The results show that performance of the MHD channel with segmented electrodes is better than that with continual electrodes with the increase of Hall parameter.     

Hyper Heuristic Approach for Design and Optimization of Satellite Launch Vehicle

Satellite launch vehicle lies at the cross-road of multiple challenging technologies and its design and optimization present a typical example of multidisciplinary design and optimization(MDO) process.The complexity of problem demands highly effi-cient and effective algorithm that can optimize the design.Hyper heuristic approach(HHA) based on meta-heuristics is applied to the optimization of air launched satellite launch vehicle(ASLV).A non-learning random function(NLRF) is proposed to con-trol low-level meta-heuristics(LLMHs) that increases certainty of global solution,an essential ingredient required in product conceptual design phase of aerospace systems.Comprehensive empirical study is performed to evaluate the performance advan-tages of proposed approach over popular non-gradient based optimization methods.Design of ASLV encompasses aerodynamics,propulsion,structure,stages layout,mass distribution,and trajectory modules connected by multidisciplinary feasible design approach.This approach formulates explicit system-level goals and then forwards the design optimization process entirely over to optimizer.This distinctive approach for launch vehicle system design relieves engineers from tedious,iterative task and en-ables them to improve their component level models.Mass is an impetus on vehicle performance and cost,and so it is considered as the core of vehicle design process.Therefore,gross launch mass is to be minimized in HHA.     

脉冲爆震火箭发动机高频实验研究

为了研究脉冲爆震发动机的高频工作特性,以航空煤油和压缩氧气为推进剂,采用爆震增强装置,增大推进剂供给压力以及增大电磁阀控制气压力等措施,在脉冲爆震火箭发动机模型上进行了实验,成功获得45Hz时的爆震压力波形。实验结果表明,频率增高,爆震波峰值压力下降,有利于加速缓燃向爆震的转变(Defla-gration to Detonation Transition,DDT)。当爆震充分发展时,爆震波波速基本不变,峰值压力上升时间趋于定值。工作频率为45 Hz时,爆震波峰值的压力为3.2 MPa,爆震波的波速为1 715.5m/s。     

室内无人飞艇系统地面工作站设计

无人飞艇作为重新兴起的飞行器在军事和民用方面具有广泛的应用价值,本文针对异型无人飞艇监测和控制的要求,采用VC＋＋可视化语言为开发工具,在地面站中实现遥测数据接收及显示、采用PID调节实现飞艇按规定航迹飞行、飞艇航迹的实时显示、选择不同飞艇进行飞行任务编辑等功能。