大型壁板数控钻铆的三点快速调平算法

 针对传统机翼壁板铆接过程中托架调平所存在的问题，提出一种基于有限曲面加工区域的三点调平算法。利用机翼表面上待钻铆点附近三点的坐标来表征该铆接区域的空间姿态，通过钻铆系统的几何结构模型所确定的坐标变化矩阵，逆解出调平所需的各运动副位移增量。在钻铆系统结构模型和机翼曲面方程的基础上建立三点选取的优化模型，并利用外点罚函数法确定其优化解。西安飞机工业(集团)责任有限公司ARJ21新支线飞机的机翼壁板试验件数控钻铆结果表明，该算法能够实现较高的加工精度和调平效率。     

Multi-objective optimization of aircraft design for emission and cost reductions

Pollutant gases emitted from the civil jet are doing more and more harm to the environ- ment with the rapid development of the global commercial aviation transport. Low environmental impact has become a new requirement for aircraft design. In this paper, estimation method for emis- sion in aircraft conceptual design stage is improved based on the International Civil Aviation Orga- nization （ICAO） aircraft engine emissions databank and the polynomial curve fitting methods. The greenhouse gas emission （CO2 equivalent） per seat per kilometer is proposed to measure the emis- sions. An approximate sensitive analysis and a multi-objective optimization of aircraft design for tradeoff between greenhouse effect and direct operating cost （DOC） are performed with five geom- etry variables of wing configuration and two flight operational parameters. The results indicate that reducing the cruise altitude and Mach number may result in a decrease of the greenhouse effect but an increase of DOC. And the two flight operational parameters have more effects on the emissions than the wing configuration. The Pareto-optimal front shows that a decrease of 29.8% in DOC is attained at the expense of an increase of 10.8% in greenhouse gases.     

Dynamic analysis of C/C composite finger seal

A seal device as an important component of aeroengines has decisive influence on per- formance, reliability, and working life of aeroengines. With the development of aeroengines, demands on the performance characteristics of seal devices are made strictly. Finger seal as a novel kind of sealing device, recently attracts more and more attentions in academic circles and engineer- ing fields at home and abroad. Research on finger seals has been extensively developed, especially on leakage and wear performances under dynamic conditions. However, it is a pity that the work on finger seals has been limited with a single approach that is improving the performance by structural optimization; in addition, the technology of dynamic analysis on finger seals is weak. Aiming at the problems mentioned above, a distributed mass equivalent dynamic model of finger seals considering the coupling effect of overlaid laminates is established in the present paper, the dynamic perfor- mance of 2.5 dimension C/C composite finger seal is analyzed with the model, and then the effects of fiber bundle density and fiber bundle preparation direction on finger seal＇s dynamic performance are discussed, as well as compared with those of Co-based alloy finger seal. The current work is about dynamic analysis of finger seals and application of C/C composite in this paper may have much academic significance and many engineering values for improving research level of finger seal dynamics and exploring feasibility of C/C composite being used for finger seals.     

Adaptive Gaussian sum squared-root cubature Kalman filter with split-merge scheme for state estimation

The paper deals with state estimation problem of nonlinear non-Gaussian discrete dynamic systems for improvement of accuracy and consistency. An efficient new algorithm called the adaptive Gaussian-sum square-root cubature Kalman filter（AGSSCKF） with a split-merge scheme is proposed. It is developed based on the squared-root extension of newly introduced cubature Kalman filter（SCKF） and is built within a Gaussian-sum framework. Based on the condition that the probability density functions of process noises and initial state are denoted by a Gaussian sum using optimization method, a bank of SCKF are used as the sub-filters to estimate state of system with the corresponding weights respectively, which is adaptively updated. The new algorithm consists of an adaptive splitting and merging procedure according to a proposed split-decision model based on the nonlinearity degree of measurement. The results of two simulation scenarios（one-dimensional state estimation and bearings-only tracking） show that the proposed filter demonstrates comparable performance to the particle filter with significantly reduced computational cost.     

PIV技术在复杂二相流场中的应用

光学元器件随飞行器在大气中飞行时,其工作性能越来越多地受到大气悬浮汇聚微粒的影响。大气微粒在复杂流场中呈现何种运动汇聚效应,对于合理准确评估机载光学元器件的工作效能具有十分重要的工程意义,而复杂气动流场中微粒分布状态的预估一直是飞行器外界环境研究中的一个难点。气动问题的复杂性、大气中微粒的多样性一直是制约各种试验手段展开、数值模型建立的主要因素。利用先进的激光粒子图像技术,在风洞中对舵面旋涡主导的复杂流场中的微粒速度及分布特性进行了实验研究。在测量舵面翼梢脱落旋涡特性的基础上,通过激光片光扫描流场全域,同时高帧频CCD相机同步曝光,利用PIV 拍摄到的流场中涡流截面内微粒分布的瞬态图像。结合图像后处理技术,对原始粒子图像进行互相关、二值化处理,通过对图像区域内的灰度值计算,统计相对流场截面内的粒子浓度系数,得到在复杂旋涡结构流场内瞬态粒子的分布特性规律。研究结果表明,利用大气中微粒在激光片光下的米氏散射原理,可以有效地拍摄到复杂流场结构下粒子光学散射及分布的特性图像,解决了传统环境测试设备无法对复杂条件下流场内粒子分布进行实时测量的缺陷;在旋涡为主导的流场中,大气中的微粒由向心力牵引,在涡核周围达到平衡运动状态,微粒环绕涡核形成一条环状带,这一区域中的粒子浓度系数要远大于自由流场中的微粒,涡核中心粒子呈“空洞”状态。     

柔性热膜剪应力传感器水下测量温度修正

柔性热膜微传感器应用于流体壁面剪应力测量时,流体温度对传感器输出有很大影响,因此有必要对工作在非标定温度下的传感器输出信号进行修正补偿。重点研究了水下测量时传感器输出与水温的关系以及温度修正方法。通过分析传感器过热比和流体物理性质与温度的相关性,建立了流体温度与传感器过热比和标定系数的函数关系。在此基础上,提出了一种用于水下剪应力测量的温度修正方法,可以有效减小水温对传感器输出的影响。经实验验证,该方法可以使工作在25℃、28℃水温环境下的传感器输出值与其20℃标定值的相对误差从23．7％和37．1％回落到0．82％和0．83％。     

微小型数据采集系统优化设计方法研究

微小型数据采集系统一般是基于微控制器进行设计的,存储设备主要为SD卡,由于微控制器资源有限,因此很难在保证微小型数据采集系统较高采集速度的同时保证采集系统的可靠性.针对该问题,本文分析了影响数据采集系统采集速率及可靠性的主要影响因素,推导了DMA缓冲区设置大小与数据采集系统采集速率及可靠性之间的模型,并设计了数据采集系统主要参数标定与验证试验.试验结果表明,本文提出的数据采集系统设计方法合理、可根据数据采集处理器内存大小、SD卡文件系统性能指标设计数据采集系统,确保数据采集系统的可靠性,对提高系统设计效率、降低微小型数据采集系统的设计成本以及后续改进完善数据采集系统奠定了重要的理论基础.     

An extrapolation approach for aeroengine’s transient control law design

Transient control law ensures that the aeroengine transits to the command operating state rapidly and reliably. Most of the existing approaches for transient control law design have complicated principle and arithmetic. As a result, those approaches are not convenient for application. This paper proposes an extrapolation approach based on the set-point parameters to construct the transient control law, which has a good practicability. In this approach, the transient main fuel control law for acceleration and deceleration process is designed based on the main fuel flow on steady operating state. In order to analyze the designing feature of the extrapolation approach, the simulation results of several different transient control laws designed by the same approach are compared together. The analysis indicates that the aeroengine has a good performance in the transient process and the designing feature of the extrapolation approach conforms to the elements of the turbofan aeroengine.     

民用飞机座舱二氧化碳气体浓度分析研究

对民用飞机座舱CO_2气体浓度进行了分析研究,阐述了民用飞机CO_2气体浓度的相关要求、计算模型,同时利用该模型对某型民用飞机未满载时座舱CO_2气体浓度进行了计算,并与试验结果进行了对比,验证了计算模型的正确性。之后利用该模型计算了某型民用飞机满载时座舱CO_2气体浓度,以表明某型民用飞机座舱CO_2气体浓度对相关要求的符合性。     

PI controller relay auto-tuning using delay and phase margin in PMSM drives

This paper presents an auto-tuning method for a proportion plus integral（PI） controller for permanent magnet synchronous motor（PMSM） drives, which is supposed to be embedded in electro-mechanical actuator（EMA） control module in aircraft. The method, based on a relay feedback with variable delay time, explores different critical points of the system frequency response.The Nyquist points of the plant can then be derived from the delay time and filter time constant.The coefficients of the PI controller can then be obtained by calculation while shifting the Nyquist point to a specific position to obtain the required phase margin. The major advantage of the autotuning method is that it can provide a series of tuning results for different system bandwidths and damping ratios, corresponding to the specification for delay time and phase margin. Simulation and experimental results for the PMSM controller verify the performance of both the current loop and the speed loop auto-tuning.