Numerical study on similarity of plume infrared radiation between reduced-scale solid rocket motors

This study seeks to determine the similarities in plume radiation between reduced and full-scale solid rocket models in ground test conditions through investigation of flow and radiation for a series of scale ratios ranging from 0.1 to 1. The radiative transfer equation(RTE) considering gas and particle radiation in a non-uniform plume has been adopted and solved by the finite volume method(FVM) to compute the three dimensional, spectral and directional radiation of a plume in the infrared waveband 2–6 μm. Conditions at wavelengths 2.7 μm and 4.3 μm are discussed in detail, and ratios of plume radiation for reduced-scale through full-scale models are examined. This work shows that, with increasing scale ratio of a computed rocket motor, area of the hightemperature core increases as a 2 power function of the scale ratio, and the radiation intensity of the plume increases with 2–2.5 power of the scale ratio. The infrared radiation of plume gases shows a strong spectral dependency, while that of Al_2O_3 particles shows spectral continuity of gray media.Spectral radiation intensity of a computed solid rocket plume's high temperature core increases significantly in peak radiation spectra of plume gases CO and CO_2. Al_2O_3 particles are the major radiation component in a rocket plume. There is good similarity between contours of plume spectral radiance from different scale models of computed rockets, and there are two peak spectra of radiation intensity at wavebands 2.7–3.0 μm and 4.2–4.6 μm. Directed radiation intensity of the entire plume volume will rise with increasing elevation angle.     

复合材料发射架无损检测研究进展

本文介绍了复合材料缺陷对发射架构件的影响,论述了MMS公司的线性扫描热波检测、声-超声波检测、超声波检测技术,比较了检测方法的准确率、可信度和效率。指出将无损检测技术与自动化检测、信号采集、图像处理等现代化技术相结合,将在复合材料发射架检测中发挥重大作用。     

滚转舰炮制导炮弹的空间多约束导引与控制一体化设计

在大口径舰炮制导炮弹打击近岸机动目标的末段，考虑攻击角、控制受限、视线（LOS）角速率测量受限等约束，提出了一种基于块动态面与扩张状态观测器（BDSESO）的多约束空间导引与控制一体化设计（IGC）方法。构建了滚转制导炮弹的空间导引与控制一体化的严块反馈串级模型，运用扩张状态观测器估计视线角速率和目标机动、建模误差、风等系统内外不确定干扰。为了在有限时间内零化视线角跟踪误差与视线角速率，采用自适应指数趋近律设计非奇异终端滑模，通过自适应动态面控制有效镇定串级系统并避免微分膨胀，引入自适应Nussbaum增益函数补偿控制受限的饱和非线性。通过Lyapunov理论证明了视线角跟踪误差、视线角速率的有限时间收敛性与全系统状态的一致最终有界性。半实物仿真实验表明：该方法使制导炮弹在打击具有不同机动形式的目标时，均具备较好的末制导性能。     

IR radiation characteristics of rocket exhaust plumes under varying motor operating conditions

The infrared(IR) irradiance signature from rocket motor exhaust plumes is closely related to motor type,propellant composition,burn time,rocket geometry,chamber parameters and flight conditions.In this paper,an infrared signature analysis tool(IRSAT) was developed to understand the spectral characteristics of exhaust plumes in detail.Through a finite volume technique,flow field properties were obtained through the solution of axisymmetric Navier-Stokes equations with the Reynolds-averaged approach.A refined 13-species,30-reaction chemistry scheme was used for combustion effects and a k-e-Rtturbulence model for entrainment effects.Using flowfield properties as input data,the spectrum was integrated with a line of sight(LOS) method based on a single line group(SLG) model with Curtis-Godson approximation.The model correctly predicted spectral distribution in the wavelengths of 1.50–5.50 lm and had good agreement for its location with imaging spectrometer data.The IRSAT was then applied to discuss the effects of three operating conditions on IR signatures:(a) afterburning;(b) chamber pressure from ignition to cutoff;and(c) minor changes in the ratio of hydroxyl-terminated polybutadiene(HTPB) binder to ammonium perchlorate(AP) oxidizer in propellant.Results show that afterburning effects can increase the size and shape of radiance images with enhancement of radiation intensity up to 40%.Also,the total IR irradiance in different bands can be characterized by a non-dimensional chamber pressure trace in which the maximum discrepancy is less than 13% during ignition and engine cutoff.An increase of chamber pressure can lead to more distinct diamonds,whose distance intervals are extended,and the position of the first diamond moving backwards.In addition,an increase in HTPB/AP causes a significant jump in spectral intensity.The incremental rates of radiance intensity integrated in each band are linear with the increase of HTPB,and the growth rates of radiance intensities in some bands reach up to 50% as HTPB weight increases by 3%.     

无人机红外辐射特性测量方法

无人机飞行时红外辐射特性测量受多方面因素影响，测量精度低，不能满足试验要求。采用室内标定、室外成像进行红外辐射特性反演，利用FasCode软件对大气传输进行估算，对测量结果进行修正，获得无人机红外辐射特性，测量结果与实际情况一致，测量方法有效。     

飞机引导控制指令研究

飞机引导控制指令的选择直接影响到飞行控制性能,对引导控制指令的种类和优劣进行研究具有重要意义。首先,以纵向为例,分析认为可选择的引导控制指令有俯仰角指令、法向过载指令和垂直速率指令;然后,在几个合理假设的基础上,采用理论分析方法对上述三种引导控制指令进行比较,所得结论如下:在抑制风对迎角、高度的干扰,以及抑制参数摄动对高度的干扰等方面,能力由高到低分别为过载指令、垂直速率指令和俯仰角指令。最后,通过仿真对上述结论进行了辅助验证。     

Three-dimensional analysis of relationship between relative orientation and motion modes

Target motion modes have a close relationship with the relative orientation of missile-totarget in three-dimensional highly maneuvering target interception. From the perspective of relationship between the sensor coordinate system and the target body coordinate system, a basic model of sensor is stated and the definition of relative angular velocity between the two coordinate systems is introduced firstly. Then, the three-dimensional analytic expressions of relative angular velocity for different motion modes are derived and simplified by analyzing the influences of target centroid motion, rotation around centroid and relative motion. Finally, the relationships of the relative angular velocity directions and values with motion modes are discussed. Simulation results validate the rationality of the theoretical analysis. It is demonstrated that there are significant differences of the relative orientation in different motion modes which include luxuriant information about motion modes. The conclusions are significant for the research of motion mode identification,maneuver detection, maneuvering target tracking and interception using target signatures.     

中美大学生职业生涯规划指导模式的比较

多年的高校扩招,使大学生就业难成为全社会持续关注的热点.就业难的主要原因是人职难以匹配,其症结可归结为大学生没有清晰的职业发展目标,缺乏职业规划.大学生职业生涯规划指导在我国起步较晚,仅有十几年的时间,这一工作尚处于摸索阶段,难免问题多、效果不佳;而大学生职业生涯规划起源于美国,已经有上百年的发展历史,美国并且已经探索出一套行之有效的职业生涯规划指导模式.文章对中美高校职业生涯规划指导进行分析和对比,查找我国职业生涯规划指导存在的问题,总结美国职业生涯规划教育的经验,通过借鉴美国高校的经验,并结合我国的实际情况,探索适合我国大学生职业生涯规划指导的新模式.     

高校毕业设计（论文）环节存在问题及对策研究

分析高校毕业设计（论文）教学环节存在的8个方面的问题，提出“建立毕业设计（论文）规范、制度”“加强毕业设计（论文）工作监控”“进行高校毕业设计（论文）工作的量化考核创新毕业设计（论文）指导模式推行毕业设计（论文）管理和指导网络化”和“毕业设计（论文）融入信息素质教育”6个方面的对策，简略介绍西安航空学院在毕业设计（论文）环节教改研究方面取得的主要成果和今后研究的主要问题。     

舰载无人机撞网回收自适应制导技术

针对无人机自动着舰撞网回收过程中目标舰船处于运动状态的特点,借鉴导弹导引律的比例导引法提出了基于视线角的制导律,并引入反步法的设计思想以提高制导律的自适应性。基于视线角的制导律使无人机的轨迹倾斜角变化率与视线角变化率成比例,通过控制视线角来跟踪下滑轨迹倾斜角。采用该导引律可以减小无人机运动对目标舰船参数变化的敏感性,从而获得较为稳定的下滑轨迹。仿真结果表明了该制导律的可行性,并且该制导律具有较强的鲁棒性。