不同外形建模方法对机翼气动特性的影响

飞机设计和制造过程中外形建模方法对飞机气动特性有较大影响。针对一种大型商用飞机机翼外形方案,基于样条曲线曲面理论,以内外翼整体或分段造型、调整曲面特征截面数量等不同方法进行三维外形建模,同时借助CFD数值计算得出巡航状态下各外形的气动参数,对比分析几种建模方法对机翼外形和气动特性的影响,并总结出一些关于飞机机翼外形建模的基本原则,对飞机设计和制造工程有一定参考价值。     

基于随机过程的可靠性建模

基于Wiener过程、Gamma过程和逆高斯(Inverse Gaussian,IG)过程等随机过程的可靠性建模方法在装备可靠性评估中逐步得到应用.针对3类考虑随机影响的随机过程模型,分别阐述了各类模型在一元性能退化建模、二元性能退化建模、加速退化建模和竞争失效建模等情形下的应用情况,并展望了下一步研究方向.研究工作对...     

基于BP网络的光纤陀螺刻度因子建模研究

针对光纤陀螺(FOG)随温度呈非线性变化的特性,提出了采用BP神经网络对刻度因子的温度误差建模的方法,以减小光纤陀螺输出误差;用BP网络对其建模的结果和传统的建模结果进行了比较,结果表明采用BP神经网络对刻度因子的建模是非常有效的.     

基于ACIS平台开发笔式三维建模系统的关键技术

讨论了基于ACIS平台进行笔式三维建模所需解决的关键技术,并给出了相应的解决方案.介绍了基于ACIS平台的开发技术,重点讨论了二维草图的识别、坐标映射和笔式三维特征建模等关键技术,并给出了PenSketch3D的三维建模实例.     

Computation of unsteady turbomachinery flows: Part 1—Progress and challenges

There are numerous unsteady flow influences in turbomachinery. These can potentially make a substantial total impact on efficiency, and hence the environment and operating costs over the life of a gas turbine engine. These unsteadiness sources are reviewed. Also, the turbomachinery zones where unsteady modeling is mandatory for meaningful solutions is outlined. The various unsteady modeling hierarchies are reviewed. These range from linear harmonic to Direct Numerical Simulations (DNS). Unsteady reduced order modeling encompassing deterministic stresses and body forces are reviewed. Hierarchies are presented for different modeling lineages and fidelity levels. Mixed fidelity methods are proposed, where low and high fidelity treatments are combined. For example, Large Eddy Simulation (LES) and Unsteady Reynolds Averaged Simulations (URANS) being combined with body forces to provide appropriate system boundary conditions.A daunting array of modeling and numerical methods and strategies are found for the user to select. Each has their own theoretical limitations. Clearly a user must be aware of these. Reported performances of the different approaches are found to vary considerably between relatively similar applications. The reviewed work suggests that Computational Fluid Dynamics (CFD), as ever, is an activity that needs strong reviewing of processes, tools and overseeing of modeling practices. With regard to LES, grid densities used for typical complex geometry simulations currently appear to be too coarse. This reflects the lack of current computational performance and hence the need for reduced order models.     

某型飞机研制过程建模和模型分析

介绍了某型飞机研制过程建模和模型分析的研究情况,着重介绍了开展该项研究工作的背景、活动与过程的描述,过程建模的准备、过程建模和模型分析的结果及其应用方向。此外,针对该型飞机研制过程模型分析的情况,提出了对其过程改进的一些粗浅看法。     

基于赋时可重构Petri网的可重构制造系统建模

系统建模是可重构制造系统生产管理控制技术的基础。分析了可重构制造系统的建模需求,提出基于赋时可重构Petri网的可重构制造系统建模的方法。该建模方法是先建立可重构制造系统当前系统的赋时可重构Petri网模型,再通过修改其建模元素得到可重构制造系统重构后系统的赋时可重构Petri网模型。实例研究表明基于赋时可重构Petri网的可重构制造系统建模方法能够满足可重构制造系统的建模需求,因此它是可重构制造系统的正确的形式化表示。     

直升机结构动特性建模技术研究

在直升机设计阶段通过建模分析进行全机动特性设计，准确地预测全机振动响应是控制和降低直升机振动水平的关键技术，本文以直11型直升机为研究对象，对机体结构的动特性建模技术进行了深入的研究，采用从部件到全机建模的研究策略，把整个机体分成尾段，舱门，机身段，分别进行有限元建模，动特性试验，相关分析，模型修改技术和建模准则的研究，在此基础上，对部件连接界面建模分析，组建修改后的各部件模型，建立全机动特性分析模型，通过对直11型机全机动力学建模，试验相关分析与模型修改，大大增强了分析模型的预测能力，达到了40Hz以内的频率误差小于11％的预测精度，突破了对直升机复杂结构建模关键技术，建立了适用于直升机结构动力学分析的建模准则，在直11型机动特性设计中取得了成功。     

Control-oriented Modeling for Air-breathing Hypersonic Vehicle Using Parameterized Configuration Approach

This article presents a parameterized configuration modeling approach to develop a 6 degrees of freedom (DOF) rigid-body model for air-breathing hypersonic vehicle (AHV). The modeling process involves the parameterized configuration design, inviscous hypersonic aerodynamic force calculation and scramjet engine modeling. The parameters are designed for airframe-propulsion integration configuration, the aerodynamic force calculation is based on engineering experimental methods, and the engine model is acquired from gas dynamics and quasi-one dimensional combustor calculations. Multivariate fitting is used to obtain analytical equations for aerodynamic force and thrust. Furthermore, the fitting accuracy is evaluated by relative error (RE). Trim results show that the model can be applied to the investigation of control method for AHV during the cruise phase. The modeling process integrates several disciplines such as configuration design, aerodynamic calculation, scramjet modeling and control method. Therefore the modeling method makes it possible to conduct AHV aerodynamics/propulsion/control integration design.     

FMS的对象建模

进行FMS建模研究是研究FMS动态仿真软件的自动生成的前提.面向对象源于仿真,采用面向对象的建模方法,在FMS的分析、建模以及动态调度软件自动生成有着极大的优越性.本文首先研究了对象建模的方法,并以之为指导,建立了FMS的对象模型、功能模型和动态模型,为FMS动态仿真软件的自动生成打下了基础.     

Physical Modeling of Electromagnetic Interference in Unmanned Aerial Vehicle under Action of the Electric Transport Contact Network

The technique was developed for studying the noise immunity of electronic systems of unmanned aerial vehicles on the basis of physical modeling. The mathematical models, the scheme of a test bench, and examples of parameter calculation for physical modeling of electromagnetic interference in communication lines under the influence of switching magnetic fields of electric transport contact network are proposed. An example of physical modeling of electromagnetic interference in communication lines is presented.     

排球球缝随机气动力辨识建模

本文应用Ｈ（Ｈｏｕｓｅｈｏｌｄｅｒ）变换求解病态法方程之最小二乘法及三次样条函数最小二乘法，对不同球缝随机性气动力模型进行辨识，提高了参数估计精度。讨论了不同球缝和各种发政治协商会议方式气动力的建模方法，给出了数学模型，并进行了验证，所得结果与实践经验一致。表明气动力模型较符合实际，建模方法可行，模型简单实用，为研究运用球缝发飘球技术，提供了重要的模型依据。     

柱塞泵热力学建模与仿真

针对航空行业广泛应用的柱塞泵的热力学特性,提出了一种分析和建模的方法.应用能量守恒定律推导并建立了集中参数的航空柱塞泵的热力学模型,并针对柱塞泵的内部结构进行了较详细的传热分析.将此建模和分析的方法应用于包含航空柱塞泵的一个典型液压回路.通过对航空柱塞泵的热力学实验与仿真结果的比较证明了建模方法的有效性.     

直升机飞行动力学数学建模问题

直升机飞行动力学数学模型是飞行控制系统设计的基础,也是直升机飞行品质设计和评估的主要手段。直升机是一个多体系统,在直升机飞行动力学建模过程中,必须考虑旋翼、机体与升力面等的运动耦合、惯性耦合、结构耦合和气动耦合以及非定常、非线性特性,给出各个运动部件的物理模型及其数学表达形式,是对不同假设、子模型进行分析和综合的一个复杂的过程。鉴于此,简要回顾了单旋翼带尾桨直升机飞行动力学数学模型的研究现状,着重描述了直升机飞行动力学数学建模中的旋翼气动力建模、直升机气动干扰建模、旋翼/发动机建模以及直升机飞行动力学模型的集成与综合的研究现状与研究进展。最后,针对直升机飞行动力学的数学建模提出了今后的研究重点。     

多卫星系统资源建模与能力计算方法研究

针对复杂多卫星系统的建模与能力计算问题，借鉴超分子化学中的自组装机制，给出了多卫星系统资源的自主组装规则，建立了互补型及增强型2类聚合体模型，进而分别给出了2类聚合体能力计算方法，可以实现系统资源的自主聚合。最后，在给定多卫星系统资源条件下，完成了2类聚合体的能力计算，为多卫星系统建模与能力计算提供了一种新的研究思路。     

模拟中性大气边界层中污染物传输与扩散的动力相似讨论

文章从湍流雷诺数相等出发,推导出风洞中模拟中性大气边界层动力相似准则一充分发展的湍流中,运动相似的流动动力也相似。文章还讨论了模拟烟流抬升和扩散的相似准则,概述了国内外一些主要实验室应用的近似模拟技术。     

滞止式温度传感器动态理论建模研究

根据滞止式温度传感器的换热原理建立了动态理论传热模型,采用数值计算方法对模型方程进行了求解,并对计算结果进行了分析.     

Unsteady aerodynamic modeling at high angles of attack using support vector machines

Accurate aerodynamic models are the basis of flight simulation and control law design.Mathematically modeling unsteady aerodynamics at high angles of attack bears great difficulties in model structure determination and parameter estimation due to little understanding of the flow mechanism.Support vector machines(SVMs)based on statistical learning theory provide a novel tool for nonlinear system modeling.The work presented here examines the feasibility of applying SVMs to high angle-of-attack unsteady aerodynamic modeling field.Mainly,after a review of SVMs,several issues associated with unsteady aerodynamic modeling by use of SVMs are discussed in detail,such as selection of input variables,selection of output variables and determination of SVM parameters.The least squares SVM(LS-SVM)models are set up from certain dynamic wind tunnel test data of a delta wing and an aircraft configuration,and then used to predict the aerodynamic responses in other tests.The predictions are in good agreement with the test data,which indicates the satisfying learning and generalization performance of LS-SVMs.     

基于Modelica和Dymola的压气机系统的建模与仿真方法

基于压气机性能方程推导出一种新的压气机级的数学模型，并在这一模型基础上用Modelica语言和Dymola编译器建立了计算机仿真模型，编成了压气机系统仿真程序。还描述了压气机仿真程序建模系统和面向对象的体系结构，介绍了压气机系统特性分析的应用例子，并进行了仿真验证。结果表明，采用建立的仿真模型能够用来模拟压气机性能。