Investigation on the Thermal Conductivity of 3-Dimensional and 4-Directional Braided Composites

It is vital to choose a factual and reasonable micro-structural model of braided composites for improving the calculating precision of thermal property of 3-D braided composites by finite element method (FEM). On the basis of new microstructure model of braided composites proposed recently, the model of FEM calculation for thermal conductivity of 3-dimennsional and 4-directional braided composites is set up in this paper. The curves of coefficient of effective thermal conductivity versus fiber volume ratio and interior braiding angle are obtained. Furthermore, comparing the results of FEM with the available experimental data,the reasonability and veracity of calculation are confirmed at the same time.     

Study on dynamic stiffness of supporting structure and its influence on vibration of rotors

The dynamic response of the rotor depends on not only itself but also the dynamical characteristics of the structures that support it. In this paper, the coupling vibration characteristics of the rotor and supporting structure are studied using one simple rotor-supports model firstly, and then the dynamic stiffness of the typical supporting structure of an aero-engine is investigated in use of both numerical and experimental methods. While, one simulation strategy is developed to include dynamic...     

正弦压力信号幅值测量无差算法研究

正弦压力校准常用比较法,通过比较标准压力传感器与被校压力传感器在同一正弦压力源中的响应完成被校传感器的幅值校准。对正弦压力信号幅值的测量算法进行了研究,提出了一种控制采样频率为标准激励信号频率整数倍的算法,可实现幅值的无差运算,理论推导和仿真实验表明,该算法能有效提高单频校准的准确度。     

星载天线展开过程立体视觉动态测量技术

介绍了基于立体视觉原理的星载天线动态展开过程测量方法,通过基于标准长度的标定方法、双目立体视觉交会坐标解算和动态多目标点识别跟踪等关键技术的研究,实现了对可展开天线各关节点在展开过程中的三维运动轨迹的测量,并实现了试验验证。试验结果表明,该方法可获得各关节点在不同时刻的三维点坐标,解算出展开运动的运动速度、加速度和展开后的面型等参数,为大型可展开天线柔性机构设计、动力学分析和展开可靠性分析等提供必要的参考。     

进口速度分布对短突扩压器性能的影响

在任意曲线坐标系下,对环型燃烧室的三维流场进行了数值计算,研究了四种不同的进口速度分布对扩压器性能的影响。计算结果表明,进口速度大小和方向都对扩压器性能有重要影响,进口速度分布均匀以及方向贴近扩压器壁面,有利于提高扩压器的性能。计算中采用标准ｋ－ε双方程紊流模型,采用控制容积法进行离散,在非交错网格体系下用ＳＩＭＰＬＥ法求解     

AHC-85航向姿态计算机中CSDB总线的应用分析

基于CSDB总线在AHC-85航向姿态计算机中的应用,阐述了CSDB总线的规范、电气特性和编码规则,并对AHC-85航向姿态计算机中CSDB总线的检测数据推算以及检测数据模拟做了详尽的分析。     

随动推力作用下柔性旋转飞行器稳定性分析

针对柔性旋转飞行器动力学问题,考虑了飞行器转速的作用,建立了计入陀螺力矩及随动推力影响的运动方程并分析了系统的动力稳定性问题。将柔性旋转飞行器简化为带有附加质量的非均匀转子结构,考虑陀螺力矩及随动推力的影响,采用剪切变形对轴向位移有影响的Timoshenko梁模型,基于有限元方法建立了运动方程,分析转速、剪切刚度及附加质量等因素对系统稳定性的影响,发现了转速作用下旋转飞行器刚体和弹性体模态耦合的新现象。结果表明：剪切刚度较小时,剪切变形对临界推力有较大影响;附加质量的大小及位置对临界推力和不稳定域有重要的影响;转速一般会诱发非均匀转子系统的弯曲模态与刚体模态合并为一个耦合模态,致使系统产生动态失稳。     

全姿态动调陀螺定北仪研究

介绍一种全姿态定北装置，它以动调陀螺仪和加速度计为测量元件，利用正切法双轴测速定北和重力加速度信息，进行全姿态方位角计算，采用浮点片TMS320C32数字信号处理器（DSP）进行计算和控制，提高了系统的运算精度和速度，可快速自动准确测出真北方位角，着重讨论基于DSP的动调陀螺定北仪的原理，信号处理和误差分析，以及与人工调平定北仪的比较。     

A novel high-order scheme for numerical simulation of wake flow over helicopter rotors in hover

Accurate prediction of tip vortices is crucial for predicting the hovering performance of a helicopter rotor. A new high-order scheme(we call it WENO-K) proposed by our research group is employed to minimize numerical dissipation and extended to numerical simulation of unsteady compressible viscous flows dominated by tip vortices over hovering rotors. WENO-K is referred to as an adaptively optimized WENO scheme with Gauss-Kriging reconstruction, and its advantage is to reduce dissipation in smoo...     

直升机缆位系统建模与仿真

针对直升机绞车收放时缆位保持问题,建立了负载出水回收进舱阶段缆位的动力学模型。由于浮力与洋流作用突然消失,负载出水后发生摆动,将负载的摆动作为带有理想约束的质点系动力学系统,采用拉格朗日方程建立动力学模型。考虑直升机悬停提升的情况进行仿真,仿真结果表明建立的数学模型能够较好的模拟负载摆动时的缆位变化。