低速风洞推力矢量试验技术研究

介绍了中国航天空气动力技术研究院FD-09低速风洞利用YF-16标模作为研究对象开发的一种推力矢量试验系统,系统利用中压气源提供的最大2.0MPa压缩空气,通过通气管路和推力矢量管道由模型尾喷管排出,用于模拟飞机喷流对全机气动特性的影响。推力矢量试验系统充分利用现有的大迎角机构预弯支杆作为模型支撑装置和引气管路,使同一次车次的试验迎角范围能够达到-6°~90°,同时极大降低管路压力损失,使得喷口最大落压比NPR超过5,并且能够实现模型腹部支撑和背部支撑两种形式的相互转换。试验采用六分量常规测力天平和推力矢量传感器以及总压传感器等,测量得到了推力矢量喷流对全机气动性能的影响以及喷管的气动性能。主要介绍整个系统布局、推力矢量管路的优化设计、测试设备以及两套喷管的典型试验结果。推力矢量试验系统在经过支撑干扰修正、喷流状态下传感器校准、压力管路化等方面做进一步的深入研究之后,将形成试验能力。     

Low-frequency unsteadiness of vortex wakes over slender bodies at high angle of attack

A type of flow unsteadiness with low frequencies and large amplitude was investigated experimentally for vortex wakes around an ogive-tangent cylinder. The experiments were carried out at angles of attack of 60–80 and subcritical Reynolds numbers of 0.6–1.8×105. The reduced frequencies of the unsteadiness are between 0.038 and 0.072, much less than the frequency of Karman vortex shedding. The unsteady flow induces large fluctuations of sectional side forces. The results of pressure measurements and particle image velocimetry indicate that the flow unsteadiness comes from periodic oscillation of the vortex wakes over the slender body. The time-averaged vortex patterns over the slender body are asymmetric, whose orientation is dependent on azimuthal locations of tip perturbations. Therefore, the vortex oscillation is a type of unsteady oscillation around a time-averaged asymmetric vortex structure.     

A new grid deformation technology with high quality and robustness based on quaternion

Quality and robustness of grid deformation is of the most importance in the field of aircraft design, and grid in high quality is essential for improving the precision of numerical simulation. In order to maintain the orthogonality of deformed grid, the displacement of grid points is divided into rotational and translational parts in this paper, and inverse distance weighted interpolation is used to transfer the changing location from boundary grid to the spatial grid. Moreover, the deformation of rotational part is implemented in combination with the exponential space mapping that improves the certainty and stability of quaternion interpolation. Furthermore, the new grid deformation technique named ‘‘layering blend deformation' is built based on the basic quaternion technique, which combines the layering arithmetic with transfinite interpolation(TFI) technique. Then the proposed technique is applied in the movement of airfoil, parametric modeling, and the deformation of complex configuration, in which the robustness of grid quality is tested. The results show that the new method has the capacity to deal with the problems with large deformation, and the ‘‘layering blend deformation' improves the efficiency and quality of the basic quaternion deformation method significantly.     

航空发动机主动稳定控制方法分析

主动稳定控制能够抑制压气机旋转失速、避免喘振,从而减小稳定裕度,扩大工作范围,使压气机性能得到最大发挥。针对航空发动机主动稳定控制关键技术,分析了以Moore-Greitzer模型为基础的压气机模型、模态控制与非线性控制两种主动控制方法,在此基础上讨论了主动稳定控制方法存在的不足,并指出了压气机模型与主动稳定控制方法的未来发展方向,可为航空发动机主动稳定控制理论研究与工程应用提供有益的参考。     

基于队形控制的电子对抗智能体协同方法

电子对抗力量协同是电子对抗力量指挥控制的"重难点"问题.随着电子对抗力量运用开始向智能化迈进,基于数据指挥的自动化指挥、智能化协同成为现代化指挥的重要组成部分.从电子对抗智能体队形控制的2种基本方法入手,通过C++仿真对比2种方法的稳定性、时效性,研究电子对抗智能体集群如何在存在侦察或干扰盲区的环境下,通过队形变化实现...     

飞机前轮转弯系统潜在故障预警方法研究

在现有计划维修体系下,飞机前轮转弯系统的故障具有隐蔽性。通过挖掘航后快速存取记录器（QAR）数据,开展前轮转弯系统潜在故障预警方法研究。首先,在分析前轮转弯系统故障模式的基础上,筛选与前轮转弯系统故障相关的QAR 监测参数并进行相应的处理;其次,基于前轮转弯系统的正常和故障案例,结合前轮转弯的操作原理,采用皮尔逊（Pe...     

基于有限元全耦合方法的耳片疲劳损伤力学分析

精确分析和预测连接耳片结构的疲劳寿命对保证飞机安全具有重要意义。采用损伤力学—有限元全耦合方法对飞机上典型连接耳片结构进行分析,得到该结构的疲劳损伤演化过程和疲劳寿命;将分析结果与疲劳寿命工程估算方法——名义应力法进行比较,证明损伤力学—有限元全耦合方法应用于结构寿命预测的可行性,并将损伤力学—有限元全耦合方法与线性Miner准则、损伤全解耦方法进行对比分析。结果表明：损伤力学有限元全耦合方法,其计算结果是唯一的、确定的,比运用线性Miner准则和损伤全解耦方法所得的结果更准确,弥补了名义应力法的不足。     

Transient aeroelastic responses and flutter analysis of a variable-span wing during the morphing process

To investigate the transient aeroelastic responses and flutter characteristics of a variablespan wing during the morphing process,a novel frst-order state-space aeroelastic model is proposed.The time-varying structural model of the morphing wing is established based on the Euler-Bernoulli beam theory with time-dependent boundary conditions.A nondimensionalization method is used to translate the time-dependent boundary conditions to be time-independent.The time-domain aerodynamic forces are calculated by the reduced-order unsteady vortex lattice method.The morphing parameters,i.e.,wing span length and morphing speed,are of particular interest for understanding the fundamental aeroelastic behavior of variable-span wings.A test case is proposed and numerical results indicate that the flutter characteristics are sensitive to both of the two morphing parameters.It could be noticed that the aeroelastic characteristics during the wing extracting process are more serious than those during the extending process at the same morphing speed by transient aeroelastic response analysis.In addition,a faster morphing process can get better aeroelastic performance while the mechanism comlexity will arise.     

An intelligent control method for a large multi-parameter environmental simulation cabin

The structure and characteristics of a large multi-parameter environmental simulation cabin are introduced.Due to the diffculties of control methods and the easily damaged characteristics,control systems for the large multi-parameter environmental simulation cabin are diffcult to be controlled quickly and accurately with a classical PID algorithm.Considering the dynamic state characteristics of the environmental simulation test chamber,a lumped parameter model of the control system is established to accurately control the multiple parameters of the environmental chamber and a fuzzy control algorithm combined with expert-PID decision is introduced into the temperature,pressure,and rotation speed control systems.Both simulations and experimental results have shown that compared with classical PID control,this fuzzy-expert control method can decrease overshoot as well as enhance the capacity of anti-dynamic disturbance with robustness.It can also resolve the contradiction between rapidity and small overshoot,and is suitable for application in a large multi-parameter environmental simulation cabin control system.     

Dynamic infrared scene simulation using grayscale modulation of digital micro-mirror device

 Dynamic infrared scene simulation is for discovering and solving the problems encountered in designing, developing and manufacturing infrared imaging guidance weapons. The infrared scene simulation is explored by using the digital grayscale modulation method. The infrared image modulation model of a digital micro-mirror device (DMD) is established and then the infrared scene simulator prototype which is based on DMD grayscale modulation is developed. To evaluate its main parameters such as resolution, contrast, minimum temperature difference, gray scale, various DMD subsystems such as signal decoding, image normalization, synchronization drive, pulse width modulation (PWM) and DMD chips are designed. The infrared scene simulator is tested on a certain infrared missile seeker. The test results show preliminarily that the infrared scene simulator has high gray scale, small geometrical distortion and highly resolvable imaging resolution and contrast and yields high-fidelity images, thus being able to meet the requirements for the infrared scene simulation inside a laboratory.