试验设计在对地观测卫星系统顶层设计中的应用研究

针对对地观测卫星系统顶层设计中存在的仿真耗时、设计空间大以及非线性约束的特点,在其优化的不同阶段构建了试验设计的应用框架：优化初期采用正交设计方法确定系统的关键性能参数,中期采用均匀设计或拉丁方设计生成仿真方案并依此进行数值仿真,后期通过稳健设计考虑系统的噪声因素,保证最终方案的鲁棒性。该框架可以缩小对地观测卫星系统的仿真规模、缩短仿真时间、提高优化效率,保证解的质量,最后通过一个实例对优化框架的效果进行了验证。     

Image based control of the “PINOCCHIO” experimental free flying platform

A free floating platform is realized with a pneumatic suspension system which enables a two-dimensional test of complex space operations, such as rendezvous and docking. The platform is equipped with a IMU and actuated via cold gas thrusters. In addition, an on-board camera is used to acquire a target and its image is processed for evaluating the control actions needed to reach it. A technique for determining the relative position and velocity with respect to target using the same visual device is proposed and realized. The novel algorithms and relevant experimental results are presented. The tested accuracy of the relative navigation system is not very high, but the guidance algorithm, which is image based and has just a weak dependence on the position information, is robust enough to perform a successful maneuver. The error between the final acquired target image and the desired final target image is of the order of one pixel, notwithstanding all the testbed disturbances.     

空间大型末端执行器捕获动力学与实验研究

以绳索式末端执行器为研究对象,基于离散化方法,采用六维弹簧柔性连接方式建立了绳索动力学模型,并引入绳索与目标间的非线性接触碰撞力和摩擦力模型,获得末端执行器捕获动力学模型,并设计了末端捕获冲击实验,验证了模型的正确性。所建模型可充分考虑绳索的空间运动状态以及捕获过程中绳索与目标间的接触碰撞过程,基于此模型可预示并预防捕获过程中瞬时的较大冲击。对于机构设计和控制器调试具有一定意义,并可作为物理试验的有效补充,解决我国未来空间大型目标捕获任务地面试验验证困难的问题。     

盘绕式伸展机构非线性屈曲模式的试验研究与数值仿真

针对盘绕式伸展机构在轨工作的特点,对其在不同钢丝绳预紧力和机构高度下的非线性屈曲模式和屈曲载荷开展了相关的试验研究。根据其几何非线性特点,采用弧长法对试验状态下结构的非线性屈曲模式进行了仿真分析。研究结果表明：(1)数值仿真计算得到的屈曲模式和屈曲载荷与试验结果一致;(2)伸展机构的屈曲模式与钢丝绳预紧力和机构高度密切相关,处于张紧状态的钢丝绳可显著提高伸展机构的轴压、弯曲承载能力。分析结果也为其他同类机构的设计和试验提供了参考依据。     

卫星导航地面试验验证的平行系统方法

应用平行系统理论,研究全球卫星导航系统（GNSS）人工建模、计算实验和平行执行的方法。首先构建GNSS平行系统框架,分析GNSS平行系统人工建模的关键技术,提出基于代理（Agent）的导航系统实体建模方法;然后根据计算实验需求,设计GNSS平行系统在人工建模、试验支持与运行维护等方面的计算实验方法及流程。在此基础上,给出GNSS平行系统的运行模式及其平行执行过程。最后,以GNSS平行系统在人员培训方面的应用为例,说明GNSS平行系统在实际GNSS运行维护方面的应用。研究结果表明,建立GNSS平行系统是提高GNSS建设和运行维护效率的有效方法。     

燃气轮机双燃料燃烧室负荷特性试验研究

为了对比双燃料燃气轮机燃烧室使用不同气液条件下的性能,在燃烧室试验台架上,采用连续气源和单火焰筒试验件,对该型双燃料燃烧室进行了天然气及轻柴油燃料条件下的燃烧效率特性、火焰筒壁面温度分布、出口温度分布、压力脉动及总压损失特性对比试验.试验结果表明:对比柴油燃料,双燃料燃烧室在使用天然气燃料时,燃烧效率稍低,火焰筒壁温偏...     

Numerical and experimental investigation on dynamic performance of bump foil journal bearing based on journal orbit

Widespread usage of bump-type foil journal bearing (BFJB) in oil-free micro-turbomachinery requires accurate predictions of dynamic performance characteristics, although it remains a challenging issue because BFJB reflects nonlinear both structurally and aerodynamically. This paper presented a simple experimental method to semi-directly obtain the minimum film thickness and dynamic stiffness of BFJB using the journal orbit. Numerical calculations and simulations are conducted to validate the experimental method. The micro-deformation and interaction of various foils are taken into consideration to improve the model precision. The results from the numerical model regarding the BFJB dynamic characteristics are compared with the experimental results coming from a dedicated test rig, which shows that the experimental results fluctuate obviously and agree not well with the numerical results at the start stage due to the presence of dry friction at that time, nevertheless, they show fantastic agreement as soon as a gas film is gradually generated to separate the shaft from the top foil. Therefore, the proposed experimental method is effective to predict film thickness and dynamic characteristics during the period from the lift-off time to the land-off time. The dynamic characteristics, along with the journal orbits also can be used to rapidly predict the dynamics behavior of rotor-bearing systems.     

Tensile properties of a composite–metal single-lap hybrid bonded/bolted joint

Hybrid bonded/bolted (HBB) joint has been widely used in engineering practice because it can overcome the potential weakness of pure bonded and pure bolted joints. However, studies on HBB joint are still at the initial stage. In this paper, tensile properties of a composite–metal single-lap HBB joint was investigated experimentally. And a detailed finite element model (FEM) was established to simulate the tensile behavior of the joint. The model was verified by the experimental results. Then the damage propagation and load transfer mechanism were explored based on the FEM. The results show that the HBB joint can provide multi-load transmission paths and resist damage propagation in the adhesive. The HBB joint has higher strength and energy absorption capacity than the pure bonded joint. And the HBB joint has greater initial damage load and tensile stiffness than pure bolted joint. Adhesive fillets can obviously improve the tensile performances of the HBB joint. Lateral stiffness of the joint boundary and testing machine show obvious effects on tensile performances of single-lap hybrid joints.     

嫦娥三号巡视器-着陆器释放分离过程关键力学问题分析

针对嫦娥三号探测器两器释放分离过程几个关键力学问题,给出两器释放分离过程的主要风险点与影响参数,应用ADAMS建立两器释放分离全过程仿真模型,开展了全过程动力学仿真与相关试验。分析得到可适应安全释放分离要求的着陆器最大着陆姿态边界与关键性能参数,为两器释放分离提供了理论支撑与依据。     

“人字形小肋”对激波/边界层干扰的影响研究

在曼彻斯特大学跨声速风洞开展激波/边界层干扰及“人字形小肋”对其影响的实验研究。在马赫数1.85流场条件下,应用高速纹影、油流、皮托压力测量和基于压敏漆的壁面压力测量技术,研究“人字形小肋”流动控制方法对激波/边界层干扰的流动分离结构与尺寸、压力分布特性与波系特征等影响。结果显示激波/边界层干扰诱发流动分离,分离区呈现三维特征,在“人字形小肋”的作用下,分离线呈现“波浪”形且整体向上游移动,干扰区流向尺寸增大,分离区高度减小且长度略增大,再附区的压力极值降低,这些特征与叶片、尖楔等微涡发生器的影响趋势相反。下一步工作中,拟针对“人字形小肋”开展参数优化研究,“人字形小肋”可能成为降低激波/边界层干扰诱发的高热流载荷的有效方法。