Gurney襟翼对翼型流场影响的数值模拟及研究

本文采用计算流体力学的方法计算了NACA23012翼型以及安装四个不同高度（1％C、2％C、3％C、4％C）Gumey襟翼翼型的流场,并比较了不同来流马赫数、气流攻角条件下的气动性能．包括升阻比、翼型表面压力系数分布和马赫数分布。计算结果表明,安装Gumey襟翼后翼型的升阻比得到提高,升力分布趋于平均,在所计算的气流条件下安装3％C高度Gumey襟翼的翼型获得了最高的升阻比。     

Gurney襟翼对翼型气动特性影响的风洞实验研究

针对风力机叶片翼型WA251A在Re=3.0×106情况下,安装Gurney襟翼时气动力的变化展开风洞实验研究.对WA251A翼型在干净翼和安装Gurney襟翼情形下的气动力进行对比,重点讨论了Gurney襟翼安装高度、安装角度及安装位置等因素对翼型气动力的影响.实验结果表明:同一安装位置安装高度的增加其增升效应越明显...     

具有Gurney襟翼的多段翼型空气动力特性分析

增大飞机的升力可以有效地缩短飞机起飞和着陆的滑跑距离 ,本文通过对高升力多段翼型有、无Gurney襟翼时的翼面边界层、尾迹速度分布及表面压力分布的测量等实验方法研究了具有Gurney襟翼时的多段翼型绕流特性及增升规律。实验研究结果表明 ,在α =8°时 ,Gurney襟翼高度为 0 .0 2c和 0 .0 5 5c时 ,使多段翼型升力系数分别增加了 1 3%和 2 2 %。Gurney襟翼的增升效果不仅与Gurney襟翼的高度密切相关 ,而且还与在翼面上的安装位置有关。     

翼型加装格尼襟翼的低雷诺数气动特性实验研究

为了研究低雷诺数下格尼襟翼对翼型气动特性的影响,通过风洞试验研究了Eppler387翼型加装0.5%～5.0%弦长高度格尼襟翼后的气动特性变化,试验雷诺数1.49×105～2.31×105。试验结果表明：低雷诺数下Eppler387翼型加装格尼襟翼后,升力系数和力矩系数明显增大,襟翼高度大于2%弦长时阻力系数显著增大。格尼襟翼在高升力系数下能够起到增大升阻比的作用,适用于微小型飞行器工作在大载荷状态,而0.5%弦长高度的襟翼还能够兼顾中小升力系数下的气动效率,同样适合于微小型飞行器在巡航状态使用。与原翼型相比,加装襟翼后最大升阻比对应的迎角提前,随襟翼高度的增加,翼型升阻比曲线峰值变得不再突出。     

基于涡流发生器和Gurney襟翼的翼型绕流流动控制试验研究

为了研究翼型扰流流动控制,设计了一种三角形涡流发生器(VG)和两种Gurney襟翼,通过Gurney襟翼与VG 组合布局的方式进行风洞试验,对比了干净翼、干净翼加Gurney襟翼、干净翼加VG及干净翼加Gurney襟翼和VG这4种状态下的试验结果.试验结果表明:安装Gurney襟翼对翼型线性段升力在同一迎角下有明显提高...     

Modeling and simulating aircraft stability and control—The SimSAC project

This paper overviews the SimSAC Project, Simulating Aircraft Stability And Control Characteristics for Use in Conceptual Design. It reports on the three major tasks: development of design software, validating the software on benchmark tests and applying the software to design exercises. CEASIOM, the Computerized Environment for Aircraft Synthesis and Integrated Optimization Methods, is a framework tool that integrates discipline-specific tools for conceptual design. At this early stage of the design it is very useful to be able to predict the flying and handling qualities of this design. In order to do this, the aerodynamic database needs to be computed for the configuration being studied, which then has to be coupled to the stability and control tools to carry out the analysis. The benchmarks for validation are the F12 windtunnel model of a generic long-range airliner and the TCR windtunnel model of a sonic-cruise passenger transport concept. The design, simulate and evaluate (DSE) exercise demonstrates how the software works as a design tool. The exercise begins with a design specification and uses conventional design methods to prescribe a baseline configuration. Then CEASIOM improves upon this baseline by analyzing its flying and handling qualities. Six such exercises are presented.     

纵列式双旋翼重型直升机操纵系统及飞控系统方案研究

通过对纵列式双旋翼重型直升机的静稳定性和动稳定性进行理论分析,找出了影响纵列式双旋翼重型直升机最关键的迎角静不稳定和速度静不稳定问题,针对上述问题提出了相应的操纵模式,并制定了操纵系统及飞控系统的初步技术方案。     

负升力返回时航天器的再入走廊与轨迹研究

研究了较大升阻比航天器采用负升力返回时的再入走廊与最优轨迹，通过数字仿真并与正升力再入时的结果比较，得到结论：采用负升力再入时的返回走廊前１／３段比采用正升力的相应部分宽度有较大增加；离轨点所耗燃料质量与热防护系统质量之和较正升力再入时的情况有一定减少。由此可见，负升力再入概念在提高有效载荷上明显优越于正升力再入概念。     

阵风减缓直接升力控制方案的仿真研究

阵内减缓技术可有效地抑制飞机飞行过程中受到阵风和湍充影响所产生的附加过载。研究阵风载荷减缓的基本原理及各种控制方案,结合我国的实际情况,提出了以副翼作为直接升力操纵面的阵风减缓控制方案,建立了直接升力控制的阵风减缓系统的数学模型,并就阵风减缓系统进行了计算机辅助设计与仿真,验证了方案的可行性。     

基于离散协同射流的翼型增升减阻方法

协同射流是一种近壁面流动的高效、低能耗主动控制技术。重点开展了一种应用离散协同射流的二维翼型增升减阻效应的数值模拟研究,分析了离散协同射流的堵塞度和喷口密集度等关键参数对流场结构、气动特性、功率消耗及能量利用率的影响效应与作用规律。在施加离散协同射流措施后,能够使翼型近壁面空间流场更有效地产生较强的相干涡结构,使得射流与主流及边界层充分混合,可显著提高同等迎角下的升力系数、明显减小阻力系数,最大升力系数提高近150%,失速攻角推迟约5°。研究表明:离散协同射流是一种显著提高翼型性能的高效流动控制方法。     

Experimental investigation and numerical analysis serpentine nozzles

The high-efficiency Shock Vectoring Control Serpentine Nozzle(SVCSN) takes into account both thrust vectoring and infrared stealth, and significantly improves the comprehensive performance of the aero-engines through an additional auxiliary duct. In this paper, the schlieren photographs at the exit of the high-efficiency SVCSN and the wall static pressure distributions were obtained by experiments, and the numerical results were used to enrich the thrust vectoring characteristics. The effects of the auxiliary injection were analyzed first to reveal the advantages of the high-efficiency SVCSN compared to the conventional SVCSN. Then, the aerodynamic parameters and the structural parameters of the high-efficiency SVCSN were investigated, including the Nozzle Pressure Ratio(NPR), the Secondary flow Pressure Ratio(SPR), the secondary flow relative area and the secondary flow injection angle. Finally, the coupling performance of the high-efficiency SVCSN is studied by using the approximate modeling technology. Results show that the auxiliary injection increases the range between the two shock legs of the ‘‘λ” shock wave induced by the secondary flow, then causes the separation zone and high-pressure boss of the down wall to expand upstream, and finally results in a prominent increase in the thrust vectoring performance. The thrust vectoring angle and Vectoring Efficiency(VE) of the high-efficiency SVCSN are about 61.6% and75.7%, respectively, higher than those of the conventional SVCSN at NPR = 6. The effects of the NPR and the SPR on the thrust vectoring performance of the high-efficiency SVCSN are coupled with each other. A larger NPR matched with a smaller SPR shows better thrust vectoring performance. The maximum fluctuations in thrust vectoring angle and VE caused by the NPR and SPR are about 22% and 64%. The VE decreases monotonously with the increase of the secondary flow relative area. Smaller secondary flow injection angle shows better thrust vector performance, and the thrust vectoring angle and VE of the secondary flow injection angle of 90° are about 20% higher than those of the secondary flow injection angle of 110° at NPR = 6. Therefore, the secondary flow relative area of 0.06 and the secondary flow injection angle of 90° are recommended.     

波音737NG飞机后缘襟翼常见故障分析及解决措施

针对波音737NG系列飞机运行期间常见的后缘襟翼系统典型故障进行了分析与整理,总结并提出了一些实践中可行的改进方法和措施.     

Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are proposed.Dual Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss.In this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response.Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated.It is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary injection.Meanwhile,the exhaust flow is deflected.In terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers.In addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios.The control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection surface.Moreover,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/％and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4.These results provide an important theoretical basis for the practical application of DTN.     

Numerical study on flow control of ship airwake and rotor airload during helicopter shipboard landing

A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes (RANS) based solver Rotorcraft AeroDynamics and Aeroacoustics Solver (RADAS), with combination of momentum source approach is employed to conduct the helicopter shipboard landing simulation. The control effects of three aerodynamic modifications of ship superstructure, i.e. ramp, notch and flap, in different Wind-Over-Deck (WOD) conditions are discussed. From the steady simulation results, the effect of spatial variation of ship airwake on rotor airloads is concluded. The aerodynamic modifications reduce the strength of shedding vortex and increase rotor normal force through delaying and relieving flow separation, and therefore are beneficial to alleviate the limitation of control inputs. By contrast, the perturbation of unsteady ship airwake can cause the serious oscillation of rotor forces during shipboard landing. The unsteady simulations show that the turbulence intensity of ship airwake and oscillatory rotor airloading, represented by Root-Mean-Square (RMS) loading, can be remarkably reduced by the ramp and notch modifications, while the flap modification has adverse effect. It means that flow control devices have large potential benefits to alleviate the pilot’s workload and improve the shipboard landing safety, but they should be well designed to avoid the introduction of more vortex, which leads to increase in disturbance of flow field.     

Information space of sensor networks: Lagrangian,energy-momentum tensor,and applications

It is a challenge to investigate the interrelationship between the geometric structure and performance of sensor networks due to the increasingly complex and diverse architecture of them. This paper presents two new formulations for the information space of sensor networks, including Lagrangian and energy–momentum tensor, which are expected to integrate sensor networks target tracking and performance evaluation from a unified perspective. The proposed method presents two geometric objects to represent the dynamic state and manifold structure of the information space of sensor networks. Based on that, the authors conduct the property analysis and target tracking of sensor networks. To the best of our knowledge, it is the first time to investigate and analyze the information energy–momentum tensor of sensor networks and evaluate the performance of sensor networks in the context of target tracking. Simulations and examples confirm the competitive performance of the proposed method.     

A combined application of micro-vortex generator and boundary layer suction in a high-load compressor cascade

In the current study, the effects of a combined application between micro-vortex generator and boundary layer suction on the flow characteristics of a high-load compressor cascade are investigated. The micro-vortex generator with a special configuration and the longitudinal suction slot are adopted. The calculated results show that a reverse flow region, which is considered the main reason for occurring stall at 7.9° incidence, grows and collapses rapidly near the leading edge and leads to two critical points occurring on the end-wall with the increasing incidence in the baseline. As the micro-vortex generator is introduced in the baseline cascade, the corner separation is switched to a trailing edge separation by the thrust from the induced vortex. Meanwhile, the occurrence of failure is delayed due to the mixed low energy fluid and main flow. The synergistic effects between the micro-vortex generator and the boundary layer suction on the performance of the cascade are superior to the baseline at all the incidence conditions before the occurrence of failure, and the sudden deterioration of the cascade occurs at 10.3° incidence. The optimal results show that the farther upstream suction position, the lower total pressure loss of the cascade with vortex generator at the near stall condition. Moreover, the induced vortex with a leg can migrate the accumulated low energy fluid backward to delay the occurrence of stall.     

旁路式、长明灯两相加力点火系统的研制

研制成一种用于涡喷发动机的旁路式、长明灯两相加力点火系统。这种点火系统特别适用于全锥加力燃烧室结构,以改进加力燃烧室性能;并能以长明灯方式工作,提高了加力燃烧室工作稳定性。点火器及喷嘴的研制是本系统的基础,而加力点火供油调节和状态调节系统的改进是研制成功的关键。