大型飞机机身曲板多轴载荷试验技术研究

根据大型运输机及客机机身壁板结构静力分析与耐久性和损伤容限试验技术需求,研制了一套能够为机身壁板施加多轴载荷的试验系统(FPTS)。该系统由轴向载荷施加组件、剪切载荷施加组件、气压载荷及环向平衡载荷施加组件构成,既能为机身曲板施加单一载荷,同时又能实现多轴载荷协调加载,解决了多轴载荷施加边界约束的相互干涉与耦合问题。试验结果表明,单轴载荷试验应变数据均匀,多轴载荷试验应变满足结构在小变形下的叠加原理。上述试验结果可为机身静强度及疲劳强度设计提供数据支持。     

机翼双梁模型的动力学修正及应用

由于全尺寸机翼有限元模型太过复杂，不能用于大型客机翼吊发动机振动载荷的传递特性研究，本文提出了一个全新的机翼双梁动力学模型概念。基于机翼双梁模型的主要模态对其结构刚度不确定参数的灵敏度分析，选取翼梁及翼肋的水平、垂直、扭转刚度参数作为有效设计变量对双梁模型进行了动力学修正，使其与全尺寸机翼有限元参考模型前6阶模态频率的最大误差小于11.11%，大大提升了机翼双梁模型的动力符合性；集成建立了大型客机“吊架-机翼-机身”全机动力有限元模型，并计算了巡航状态下发动机振动载荷经机翼传递到机身各框段的动载荷分布特性。分析结果表明：机翼双梁模型较好地满足了发动机振动载荷传递及振动传递路径分析研究需求，为民机舱内声学预计及发动机隔振安装设计提供了基础数据。     

一种新型高鲁棒性动网格技术及其应用

首先对四元数进行李代数空间指数映射,解决了多个四元数插值问题,并结合距离倒数插值方法实现网格边界扰动向空间网格的传播,建立了新型高鲁棒性的四元数变形网格技术. 针对该型动网格技术中由于大型矩阵运算量引起的运算效率低问题,同时利用四元数方法在动网格变形中具备与物面边界高阶一致性的特点,提出了分层次变形策略,避免了面向全流场网格节点的大型矩阵运算;进一步基于无限插值技术较强的逻辑保持能力,建立了面向结构网格分层混合变形方法. 充分利用多区域重叠、对接网格变形技术中隐含的并行性,基于对等式编程思想及MPI 库函数对动网格程序进行并行化编程,建立了高效高鲁棒性的变形网格技术. 以某型客机翼身组合体气动弹性分析为范例,研究了不同方法之间的计算效率以及鲁棒性,进一步将分层混合变形网格技术应用于某型支线客机全机型架外形设计与修正,验证了所建立的新型动网格技术的高效性与鲁棒性.     

气动八作动器隔振平台的主动隔振研究

多自由度隔振平台可以有效地隔离运载器传递到卫星的振动载荷。本文采用气动八作动器隔振平台实现卫星的六自由度隔振。首先应用牛顿欧拉法建立了气动八作动器隔振平台的动力学模型,设计了平台的主动控制律,然后对平台的主、被动隔振特性进行了仿真分析。仿真分析和实验结果显示主动隔振使平台各方向的低频隔振性能均得到改善。     

基于MFC的结构静态形状控制研究

宏纤维复合材料MFC(Macro Fiber Composite)具有体积小、主动控制适用性强、作动效果好等特点。本文开展了宏纤维复合材料MFC对结构静态形状主动控制研究。建立了悬臂梁结构有限元模型,并采用载荷比拟法计算得到了MFC压电作动器的驱动载荷。基于数值分析结果,搭建了悬臂梁结构主动控制实验平台,分析了不同加载电压下的悬臂梁的弯曲变形效果,进而分析MFC结构在静态形状控制中的力学性能。数值仿真和实验结果表明:在不同的静态电压加载下,结构的变形和加载电压近似呈线性关系;仿真和实验结果对比中呈现出较好的一致性,其最大位移误差为12.45%。最后讨论了MFC压电作动器自身时间蠕变特性对静态变形控制实验结果产生的影响,结果表明在大电压作用下MFC材料存在蠕变效应,在实际使用过程中需要关注。本文采用以悬臂梁为载体的实验和仿真研究方法对在其他横观各向同性材料的压电材料力学性能分析具有普遍适用性。     

压电促动器存在故障时柔性板的μ综合振动主动控制研究

利用柔性板的实验模型研究了一种考虑作动器驱动力故障的鲁棒控制器。首先识别出粘贴压电促动器的柔性板振动控制系统实验模型,基于此利用改变压电片对联接数量来模拟促动器驱动故障,并设计了将驱动力变化提取成正则不确定块对角阵的方法,同时将剩余模态表示成高通滤波器,再通过引入虚拟不确定,构建了考虑外扰抑制和控制增益约束的综合控制器。数值仿真验证了闭环系统理论上的鲁棒稳定性。实测试验结果显示,与一般的μ控制器相比,当闭环过程中出现压电促动器驱动故障时,初始外扰下,控制结束时振幅峰峰值降低了3V,持续随机外扰下,降噪量提高了近3dB。数值仿真验证了闭环系统理论上的鲁棒稳定性。实测试验结果显示,与一般的μ控制器相比,当闭环过程中出现压电促动器驱动故障时,初始外扰下,控制结束时振幅峰峰值降低了3V,持续随机外扰下,降噪量提高近了3dB。     

刚柔混合变弯度机翼控制方法研究

为实现机翼在驱动控制下弦向连续弯度变化,提出了一种刚柔混合式变后缘机翼。其中,机翼柔顺段结构采用柔性气动肌腱作为驱动装置。首先,推导了气动肌腱驱动力模型;其次,将柔顺结构等效为单关节机械臂结构,建立了其动力学模型;继而建立了基于名义模型的滑模变结构PI控制模型,并对比例系数、积分系数及滑模面参数进行了整定。在此基础上,搭建了翼肋柔顺段变弯度控制试验平台及典型机翼盒段综合偏转控制平台。验证了柔顺段结构在弹性变形范围内达到目标弯度的能力,翼肋实际变形曲线与目标变形曲线误差仅为8%;同时,对控制方法及参数的动态性能进行了测试,其作动响应时间为5.5 s,超调量为0,稳态误差为6%,表明了控制系统的合理性和有效性。最后,对翼盒进行了目标角度的综合控制试验,测试了整体系统的变结构性能。     

典型梁-缘结构鸟撞破坏的有限元分析

以某特种飞机机身处典型支撑结构为对象，建立了鸟撞击多层间隙梁-缘结构的三维有限元分析模型。在给定的三种工况下，运用大型非线性动力学有限元分析程序ANSYS/LS-DYNA的ALE-Lagrange耦合运算功能，计算得到了鸟撞击关键部位的数值结果及结构的鸟撞临界速度，考察了不同撞击点对结构动响应的影响，分析了结构鸟撞破坏机理，经与全尺寸实验结果比较，不论是结构的变形量还是破坏模式，两者均吻合较好，从而证明了本文方法及模型的正确性。     

HWB中央机体结构非线性分析与方案优化设计方法研究

作为下一代大型民用飞机最具发展潜力的机型之一,翼身融合布局民机一直以来备受关注;而其非圆截面机身结构承载效率低和稳定性差等问题曾成为制约该机型发展的主要结构设计难题,由波音公司和NASA共同提出的基于PRSEUS的中央机体结构为解决这一难题提供了技术途径。为了深入研究翼身融合布局民机中央机体结构的承载特性、非线性分析方法及其优化策略,本文针对基于PRSEUS的HWB中央机体结构,依据其几何设计要求和复杂载荷特征,建立了高保真有限元模型及其边界、载荷施加方式;依据典型载荷工况,开展了HWB中央机体结构非线性分析;最后,利用多岛遗传优化算法,对HWB中央机体结构进行了方案优化设计。对比已有文献,结果表明:HWB中央机体结构非线性分析方法具有较好的变形分布预测能力;所提出的方案优化设计策略具有一定的工程应用价值。     

大型柔性航天器动力学与振动控制研究进展

随着航天重大工程的逐步实施,航天器正朝着超高速、超大尺度、多功能的方向发展,其面临的发射和运行环境也更加恶劣.航天器发射过程中的振动及其主/被动控制、在轨运行中大型柔性航天器动力学建模与动态响应分析、结构振动与飞行器姿态的混合控制等问题越来越复杂且难于处理;航天器结构的大型化和柔性化(如大阵面天线和太阳翼等)也对其地面试验和半实物仿真提出了挑战.本文着重介绍大型柔性航天器涉及到的动力学与振动控制问题,包括航天器发射过程中的整星隔振,大型柔性结构动力学建模与振动响应分析,大型柔性航天器的结构振动与姿轨控耦合动力学及其混合控制等.提炼出航天动力学与控制领域中亟待解决的若干基础科学问题,包括:多刚柔体系统动力学建模与模型降阶(涉及大变形柔性体动力学建模、多求解器合作仿真、模型降阶、组合结构动力学建模的解析方法等);复杂结构状态空间模型构建方法与能控性(涉及状态空间模型构建的理论与实验方法、复杂结构振动控制系统的能观性与能控性等);航天器姿态运动与大型柔性结构振动的混合控制律设计(涉及姿态机动与结构振动的鲁棒混合控制、执行机构与压电控制器的协同控制等).      

Pressure Improvement on a Supercritical High-Lift Wing Using Simple and Modulated Pulse Jet Vortex Generator

In this paper, an experimental study, aimed at delaying flow separation on a high-lift device using a pulsed blowing excitation method, is reported. The main objective of this investigation was to evaluate a new pulsed jet generation strategy to enhance flow control performance. In these experiments, two types of signal waveform were implemented to produce the unsteady blowing; a simple square-wave excitation signal for the first case, and a burst modulated excitation signal for the second case. The signal modulation was the first time to be used for a fast-switching solenoid valve actuator. Another objective of this study was to evaluate a new arrangement of the jet exit slots, in the form of a vortex generator which was employed for the first time on the high-lift device. For this purpose, a NASA SC(2)-0714 airfoil with a single slotted flap was employed. The vortex generator jets emanated from the shoulder of the trailing-edge flap with excitation frequencies from 40 to 1000 Hz. Pressure distribution around the model and wake total pressure deficit were measured. The results indicated that ejection from vortex generator slot pairs was able to prevent flow separation completely in most conditions. These measurements revealed that the burst modulated excitation signal was accompanied by more aerodynamic improvements and less air consumption relative to the simple pulsed jet excitation signal. In the best flow control mode, the results showed about a 53% increase in the value of the suction pressure peak on the flap and a 38% decrease in drag with a reduction in total pressure loss.

     

Unsteady airfoil with a harmonically deflected trailing-edge flap

The effects of a harmonically deflected trailing-edge flap, actuated at different start times and amplitudes but with frequency different from the airfoil motion, on the aerodynamic loads of an oscillating NACA 0015 airfoil were investigated experimentally at Re=2.51×10⁵. Both in-phase and 180° out-of-phase flap deflections, relative to the airfoil motion, were tested. The results show that there was a large change in the hysteretic behavior of the dynamic load loops, and that the formation and detachment of the leading-edge vortex (LEV) were not affected by the flap motion, while the low pressure signature of the vortex was affected by the flap actuation start time. The later the flap actuation the larger the change in the strength of the LEV. The present flap control scheme was also found to be as effective as that achieved by a pulsed ramp flap motion, but with a reduced number of control parameters.     

定常吹气对倾转旋翼机向下载荷的影响

为进一步提高倾转旋翼机悬停状态下的有效载重,开展了定常吹气流动控制对向下载荷的影响研究。首先应用延迟脱体涡模拟(DDES)方法对翼型-90°迎角下非定常大范围分离流动结构进行了数值分析;然后分别开展了前缘吹气、后缘吹气降载措施研究,揭示了吹气降载的机理,并对不同吹气口位置和吹气动量系数的影响进行了定量分析,最后开展了前、后缘同时吹气作用下降载数值模拟研究。计算结果表明:前缘最佳吹气位置在翼型的前缘点,而后缘吹气最佳位置位于襟翼弦长的15%处;前缘吹气的降载效果要优于后缘吹气,而且吹气动量系数对向下载荷的影响较小;相对于初始未施加流动控制构型,阻力系数减小量可达到32.72%。     

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介绍了燃气作动筒气动模拟加载装置设计思路和原理，并阐述了利用斜面上升法进 行模拟加载装置设计的计算方法. 实践应用表明气动模拟加载装置方案基本能够真实、等效 的模拟弹翼气动载荷，利用该装置大大地缩短研制周期、节省研制经费，可以进行推广应用.     

High-lift airfoil trailing edge separation control using a single dielectric barrier discharge plasma actuator

Control of flow separation from the deflected flap of a high-lift airfoil up to Reynolds numbers of 240,000 (15 m/s) is explored using a single dielectric barrier discharge (DBD) plasma actuator near the flap shoulder. Results show that the plasma discharge can increase or reduce the size of the time-averaged separated region over the flap depending on the frequency of actuation. High-frequency actuation, referred to here as quasi-steady forcing, slightly delays separation while lengthening and flattening the separated region without drastically increasing the measured lift. The actuator is found to be most effective for increasing lift when operated in an unsteady fashion at the natural oscillation frequency of the trailing edge flow field. Results indicate that the primary control mechanism in this configuration is an enhancement of the natural vortex shedding that promotes further momentum transfer between the freestream and separated region. Based on these results, different modulation waveforms for creating unsteady DBD plasma-induced flows are investigated in an effort to improve control authority. Subsequent measurements show that modulation using duty cycles of 50–70% generates stronger velocity perturbations than sinusoidal modulation in quiescent conditions at the expense of an increased power requirement. Investigation of these modulation waveforms for trailing edge separation control similarly shows that additional increases in lift can be obtained. The dependence of these results on the actuator carrier and modulation frequencies is discussed in detail.     

振动翼型和襟翼的绕流特性研究

用数值模拟手段详细地研究了振动翼型和襟翼的绕流问题,数值模拟的出发方程为Euler和N-S方程,格式为Bcam-Warming格式的改进型。数值实验主要针对流场的二大特性进行的,即振动对激波的影响和振动对分离的抑制作用,结果表明:(1)随翼型或襟翼的振动激波强度和位置也相应地变化但这一变化滞后于攻角的变化;(2)振幅加大激波强度的变化和激波运动范围也加大;(3)振动频率越高对激波的影响反而较低频时要小;(4)流动条件的不同可使升力回线的走向发生变化;(5)振动对分离有明显的抑制作用。     

Control of mechanical deformation of a laminate by piezoelectric actuator taking into account the transverse shear

Summary The control of dynamic deformation of a laminate plate is conducted by applying electrical load to a piezoelectric actuator integrated into the laminate. The dynamic behavior of the laminate is analyzed in the paper taking into account the effect of transverse shear. The analytical model of the laminate is composed of fiber-reinforced laminae and piezoelectric layers constituting a symmetric cross-ply laminate rectangular plate with simply-supported egdes. It is subjected to mechanical and electrical loads acting on the piezoelectric actuator in order to compensate the effect of the mechanical loads. The behavior of the laminate is analyzed based on the first-order shear deformation theory. Closed-form solutions are obtained for the following quantities: (1) natural frequencies of the laminate plate, (2) weight functions for the deflections and rotations and (3) transient deflections due to loads varying arbitrarily with time. Illustrative examples are shown for the control of deflections caused by the mechanical loads by means of electrical voltage applied to the piezoelectric actuators.     

动载荷作用下裂隙岩体的止裂机理分析

为深层次了解裂隙岩体在动载荷作用下的动态断裂特性及止裂机理,采用TWSRC（tunnel with single radial crack）构型进行中低速冲击实验,选择砂岩作为原材料制作裂隙岩体试样,以落锤冲击试验装置与裂纹扩展计实验系统对裂纹的动态起裂、扩展及止裂过程进行全过程监测,重点研究动态破裂过程的破裂行为及止裂现象。使用有限差分法程序进行数值模拟,验证冲击实验结果的科学性与准确性。研究发现:裂隙岩体的动态断裂过程是由起裂加速-高速扩展-缓慢减速-止裂-再次起裂加速-再次高速扩展等多次循环的过程构成,且止裂区间尺寸为微秒量级;裂隙岩体止裂位置的穿晶断裂比例远小于初始起裂点,青砂岩动态断裂过程的穿晶断裂比例稍大于黑砂岩;裂隙岩体中止裂点再次起裂所需的能量,远小于预制裂纹初始起裂所需要的能量。     

Pulsed Air-jet Actuators for Flow Separation Control

The design and validation of a microfabricated pulsed air-jet actuator for practical application to flow-separation control at full-scale operating conditions on a medium/large air vehicle is presented. The actuator device is designed to generate streamwise vortices within the boundary layer and comprises a pitched and skewed orifice of 200 μm diameter through which a high velocity (200–300 m/s) jet of air can be modulated by operation of a piezoelectric microvalve. This paper describes the overall design and manufacture of the actuator device with particular reference to the impact of fluid dynamic effects on the design and operation. Key results obtained from both static and dynamic tests of a prototype device are also presented and compared with original predictions. It is shown that the device that was developed and tested fulfils all the original design requirements with regard to size, jet velocity and operating frequency. The developed device has dimensions of approximately 5 mm × 2 mm in the plane of the aerodynamic surface in which it is imbedded and a thickness of 1 mm. Peak jet velocities in excess of 300 m/s through a 200 μm diameter orifice at 500 Hz have been demonstrated with peak driving voltages of 90 V and a nominal electrical power consumption of 50 mW.     

Dielectric-barrier-discharge vortex generators: characterisation and optimisation for flow separation control

We investigated the use of dielectric-barrier-discharge plasma actuators as vortex generators for flow separation control applications. Plasma actuators were placed at a yaw angle to the oncoming flow, so that they produced a spanwise wall jet. Through interaction with the oncoming boundary layer, this created a streamwise longitudinal vortex. In this experimental investigation, the effect of yaw angle, actuator length and plasma-induced velocity ratio was studied. Particular attention was given to the vortex formation mechanism and its development downstream. The DBD plasma actuators were then applied in the form of co-rotating and counter-rotating vortex arrays to control flow separation over a trailing-edge ramp. It was found that the vortex generators were successful in reducing the separation region, even at plasma-to-free-stream velocity ratios of less than 10%.