遥测校准数据特性方程的构建与求解方法

紧密结合靶场数据处理的实际,基于传感器的动态变化特性,建立遥测校准数据的特性方程,提供相应的求解方法,对其理论特性精度进行评估,并给出具体的应用实例。     

基于起飞性能的民机升阻特性推算

针对民机起飞构型,建立了一种利用飞机的起飞性能推算其升阻特性的工程计算方法。通过对民机起飞过程的物理分析以及对特殊飞行阶段和典型飞行状态点的动力学分析与气动力参数计算,推算出计入地面效应的民机升阻特性;参考同类飞机的失速特性,对推算得到的升力曲线进行非线性修正。以B737-300民机为算例的计算结果表明,该推算方法具有一定的精准度和工程实用性,可用于不同民机型号的气动特性对比计算和分析。     

基于混合观测器的导弹有限时间收敛滑模姿态控制

为了提高非匹配非线性干扰影响下导弹姿态控制系统的性能,提出了一种基于干扰-状态混合观测器的新型有限时间收敛滑模控制器。首先,基于观测器输出构建非奇异终端滑模面,保证非匹配干扰影响下的系统误差有限时间快速收敛;其次,采用时变观测增益设计,避免了传统固定观测增益可能带来的估计尖峰问题;再次,基于超扭曲算法,在避免传统滑模控制抖振问题的同时确保滑模面有限时间可达。仿真结果表明,所设计的控制器具备强鲁棒、快速收敛以及无尖峰的控制性能。     

稳定射流环量控制的仿真研究

为改善飞行器的升阻特性,提高其机动性能,利用数值仿真技术对稳定射流在超临界翼型的作用效果进行研究。通过动量系数变化对环量控制作用效果影响规律的研究分析后发现:稳定射流环量控制与无射流情况对比,有较强的优越性,在小迎角或负迎角就可以产生较大的升力。通过对后缘半径和射流口高度的变化对环量控制作用效果影响规律的研究分析,得到圆形后缘超临界环量控制翼型的初步设计方法。计算结果可为进一步研究环量控制对飞行器的影响奠定理论基础。     

Impact of lubricant traction coefficient on cage's dynamic characteristics in high-speed angular contact ball bearing

In this paper, the formulas of elasto-hydrodynamic traction coefficients of three Chinese aviation lubricating oils, 4109, 4106 and 4050, were obtained by a great number of elasto-hydrodynamic traction tests. The nonlinear dynamics differential equations of high-speed angular contact ball bearing were built on the basis of dynamic theory of rolling bearings and solved by Gear Stiff (GSTIFF) integer algorithm with variable step. The impact of lubricant traction coeffi-cient on cage's dynamic characteristics in high-speed angular contact ball bearing was investigated, and Poincare map was used to analyze the impact of three types of aviation lubricating oils on the dynamic response of cage's mass center. And then, the period of dynamic response of cage's mass center and the slip ratio of cage were used to assess the stability of cage under various working con-ditions. The results of this paper provide the theoretical basis for the selection and application of aviation lubricating oil.     

弹性支撑条件下齿轮体的动力特性与啮合齿的动力响应

 结合齿轮的实际工作状况,建立了齿轮结构的弹性体动力学模型,进行了弹性动力学分析,得出了齿轮的弹性固有特性; 考虑了弹性支撑轴对齿轮体振动的影响,将其处理为弹性支撑,推导了弹性支撑弹簧刚度的表达式,并在弹性边界条件下,考虑了弹性圆盘对啮合齿响应的影响,建立了齿轮支撑系统的动力模型和轮齿响应计算模型,研究了齿轮支撑系统的固有特性,并与实验结果进行了对比验证; 求解了啮合齿的动力学响应,并进行了模拟仿真。研究表明采用弹性支撑条件进行齿轮支撑系统分析是真实、精确的,为齿轮弹性体的动载荷计算、动态设计和齿轮传动系统的精确动力学研究提供了一种分析方法。     

混合线性/非线性状态空间模型的边缘Rao-Blackwellized粒子滤波法(英文)

本文提出了边缘 Rao-Blackwellized 粒子滤波器(marginal Rao-Blackwellized particle filter, MRBPF)算法,算法融合了 Rao-Blackwellized 粒子滤波器(Rao-Blackwellized particle filter , RBPF)算法和边缘粒子滤波器(marginal particle filter, MPF)算法。算法中状态被分为线形和非线性两部分,分别用 MPF 和卡尔曼滤波器(Kalman Filter)进行估计。地形辅助导航(terrain aided navigation, TAN)的仿真结果表明,与 RBPF 相比,提出算法的非线性状态估计的误差均方根(root mean square error, RMSE)和误差方差分别降低了约 29%和 96%,独立粒子数提高了约80%,获得了更好的收敛结果。分析表明,现有RBPF是MRBPF的一个特例。     

Convergence Analysis of the Numerical Solution for Cathode Design of Aero-engine Blades in Electrochemical Machining

As a main difficult problem encountered in electrochemical machining （ECM）, the cathode design is tackled, at present, with various numerical analysis methods such as finite difference, finite element and boundary element methods. Among them, the finite element method presents more flexibility to deal with the irregularly shaped workpieces. However, it is very difficult to ensure the convergence of finite element numerical approach. This paper proposes an accurate model and a finite element numerical approach of cathode design based on the potential distribution in inter-electrode gap. In order to ensure the convergence of finite element numerical approach and increase the accuracy in cathode design, the cathode shape should be iterated to eliminate the design errors in computational process. Several experiments are conducted to verify the machining accuracy of the designed cathode. The experimental results have proven perfect convergence and good computing accuracy of the proposed finite element numerical approach by the high surface quality and dimensional accuracy of the machined blades.     

凝胶推进剂直圆管流动特性探讨

分析了非牛顿流体的类型,认为在液体火箭发动机中有应用前景的凝胶推进剂类型应是有屈服应力的牛顿流体或者幂律流体,关键在于胶凝剂。研究了直圆管中凝胶推进剂的流动特性,依据剪切速率可以将凝胶推进剂在直圆管中的流动分为三个区域。在第二流动区中,可以用幂律流体推导的流阻方程计算管路流阻;在第三流动区,可以近似用牛顿流体流阻方程计算流阻。     

多重网格法在混合网格中的应用

设计了一种高效的混合网格聚合方法,在此基础上应用多重网格技术来加速Navier-Stokes方程的收敛过程.方程求解采用Jamson的中心格式有限体积法.对NACA0012翼型和ONERA M6机翼的粘性绕流进行了数值模拟,算例结果与试验结果符合良好,加速收敛效果显著.