直升机/发动机系统变旋翼转速串行优化方案

提出了一种用于直升机/涡轴发动机综合控制的变旋翼转速串行优化方案.首先基于Levenberg-Marquarat(L-M)算法/一维最优搜索算法,在保证直升机飞行状态不变的情况下,寻优得到旋翼所需最小功率,再通过优化发动机操纵量,在保证发动机约束成立的条件下得到当前发动机运行最优工作点,即达到直升机巡航时油耗最小或者涡轮前温度最低.最后,在UH-60直升机/涡轴发动机综合控制仿真平台上进行了最小油耗控制模式的仿真,数字仿真结果表明了该串行优化方案的可行性.      

基于变旋翼转速的涡轴发动机优化控制

研究了涡轴发动机/旋翼一体化优化控制问题, 分析了直升机旋翼需用功率与涡轴发动机工况的关系, 旋翼转速、旋翼总距、纵向周期变距及横向周期变距对旋翼需用功率的影响.以最小旋翼需用功率为目标函数, 用线性规划算法进行发动机/旋翼性能寻优.进行了巡航状态下变旋翼转速的涡轴发动机优化的数字仿真实验, 仿真结果表明在巡航状态应用变旋翼转速的涡轴发动机优化, 可以降低油耗1.5%～5.5%, 同时降低涡轮温度4.4～16℃, 具有实际应用价值.      

涡轴发动机/直升机综合控制仿真平台设计

建立了UH-60直升机/T700涡轴发动机综合控制数字仿真平台。基于VC++环境开发了包含UH-60直升机/T700涡轴发动机综合实时模型的上位机程序,与运行机载涡轴发动机+旋翼实时模型及在线优化控制模式的下位机程序。两者基于TCP/IP协议实时通讯,可进行模拟实际直/发综合优化控制的数字仿真实验。在该数字仿真环境下,分别给出了提高直升机常规飞行性能的多种优化控制模式仿真、变旋翼转速优化控制以及快速功率跟随控制模式仿真,充分表明该平台可为新一代直/发综合系统的开发研制提供一个可靠的前期数字仿真验证。     

基于无级变速的直升机变旋翼转速控制模拟方法研究

为了扩大直升机变旋翼转速变化范围,开展了基于无级变速机构的直升机/传动系统/发动机连续变旋翼转速控制模拟方法研究。基于叶素法和容积动力学方法,建立了主旋翼/发动机综合数学模型用于直升机推进系统仿真,该模型由主旋翼简化模型和涡轴发动机部件级模型组成。在主旋翼/发动机综合模型的基础上,加入了基于能量法建立的无级变速传动装置动力学模型,通过变传动比实现变旋翼转速控制模拟,通过定常来流状态下的数字仿真,分析变旋翼转速控制过程对主旋翼和发动机状态的影响。结果表明,提出的变旋翼转速控制模拟方法在保证涡轴发动机动力涡轮转速变化小于1.5%的前提下使旋翼转速连续变化25%,建立的直升机/传动系统/发动机综合模型为变旋翼转速技术的设计与验证提供了较可靠的数字仿真平台。     

一种直升机/发动机系统最经济旋翼转速综合优化方法

为实现直升机/涡轴发动机的最经济运行,开展了直升机/发动机系统最经济旋翼转速综合优化方法研究。首先,建立简化的直升机需求功率性能计算模型与涡轴发动机性能计算模型,共同构成直升机/发动机综合系统性能计算模型;其次,围绕通过可变动力涡轮转速实现变旋翼转速方式,分别以最小直升机需求功率优化与最低发动机燃油流量为优化目标,进行最经济旋翼转速离线优化,并对比分析两种优化模式对直升机/发动机系统综合性能的影响,揭示不同工况对最经济旋翼转速的影响规律。结果表明：变动力涡轮转速下,优化直升机需求功率未必等同于优化直升机/发动机的总体性能,而桨叶固有的失速与压缩特性,会限制进一步实现直升机最经济运行的能力。此外,采用变动力涡轮转速实现变旋翼转速,几乎不影响压气机与燃气涡轮的工作线,沿着相同的工作线运行可获得更经济的直升机/发动机综合性能。     

基于在线可变导叶角的涡轴发动机优化控制

研究了基于在线可变压气机导叶角的涡轴发动机最小油耗优化控制.分析了压气机导叶角的变化对涡轴发动机的影响.提出了基于在线可变导叶角的涡轴发动机优化控制方法.最后,进行了涡轴发动机最小油耗优化控制的仿真实验.仿真结果表明通过调节压气机导叶角可以使单位功率耗油率降低3%～7%,具有实际应用价值.      

基于直升机/ 发动机综合模型的变旋翼转速控制研究

为了实现直升机旋翼转速在宽广范围内连续变化且涡轴发动机连续提供输出轴功率,采用1种扭矩序列转移控制方案来实现该传动链。通过2台涡轴发动机和2台多级变速器与旋翼协调工作,发动机依次连接或脱开旋翼,提供旋翼转速大范围内变化,并提供旋翼连续变化的功率。在扭矩转移过程中,针对发动机扭矩强扰动问题设计了鲁棒LMI控制器+ADRC扭矩前馈补偿控制器,最后基于直升机／发动机综合模型进行数值仿真,验证了扭矩转移方案的可行性。仿真结果表明：在转移过程中的扭矩强扰动对发动机动力涡轮转速的影响较小,旋翼转速可以实现较大范围内的快速平滑变化。     

直升机/涡轴发动机综合系统鲁棒抗扰控制设计

提出了一种直升机/涡轴发动机综合系统鲁棒抗扰控制方法。分别设计了基于线性矩阵不等式(LMI)的鲁棒保性能控制的直升机四通道多变量控制器和涡轴发动机转速控制器;为了进一步提高发动机自由涡轮转速环的抗扰能力,结合自抗扰控制(ADRC)方法,构建了涡轴发动机转速鲁棒保性能控制+扭矩ADRC补偿的控制方案,充分利用了ADRC控制强的干扰补偿能力,避免了鲁棒设计方法的保守性。在UH-60直升机/涡轴发动机综合模型仿真环境下通过模拟直升机大幅急速升降操作,验证了直升机/涡轴发动机综合系统所采用的鲁棒抗扰控制,尤其是涡轴发动机鲁棒自抗扰控制,具有理想的抗扰控制效果,能够抑制直升机机动操作过程中大的扭矩扰动对涡轴发动机造成的不利影响,从而使直升机具有更好的机动能力。     

一种变旋翼转速直升机/涡轴发动机非线性模型预测控制方法研究

为了实现变旋翼转速直升机/涡轴发动机快速响应控制,提出了一种基于神经网络的直升机旋翼预测模型与基于状态变量模型的涡轴发动机预测模型的新型非线性模型预测控制方法。所建目标函数除了包含转速控制指标外,还考虑了经两级变速双离合器传动机构传扭后发动机输出轴的转子动力学特性。不同飞行任务下的数值仿真结果表明:相对于PID控制器而言,非线性模型预测控制器可在满足压气机转速、发动机静强度等限制条件下使动力涡轮转速在变旋翼转速过程中的超调量减小50%,下垂量降至0.2%以内,实现了涡轴发动机的快速响应控制的同时,有利于改善发动机使用寿命。     

基于不确定性的旋翼转速优化直升机参数设计

为了提高旋翼转速优化直升机总体参数设计质量,基于不确定性多学科设计优化方法,对旋翼转速优化直升机的参数设计进行了研究。首先对最优旋翼转速的不确定性进行分析与建模,同时也考虑了直升机加工制造、材料老化引起的不确定性因素,对比发现最优旋翼转速是旋翼转速优化直升机设计中的主要不确定性因素;然后在协同优化框架下,分别建立了直升机飞行性能、直升机重量、飞行稳定性与变转速涡轴发动机性能计算模型;最后以续航性能为系统学科,悬停性能、飞行稳定性分别作为子学科,进行多学科的不确定性优化设计,得到了3种不确定性优化设计方案。通过对比分析可以发现：第2种方案为旋翼转速优化直升机的最佳参数设计方案,该方案满足悬停需用功率低于350 kW,飞行稳定性指数小于0.8等约束条件的概率不低于95.46%,并且直升机的最大航时期望值也较大。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.