详细化学反应机理对预混丙烷钝体熄火模拟影响

航空发动机熄火预测是重要关键问题之一，湍流和化学反应的非线性相互作用使预测非常困难。本文采用大涡模拟（LES）对湍流进行高精度模拟，采用概率密度函数输运方程湍流燃烧模型（TPDF）耦合JL4、Z66和H73三种化学反应机理，对预混丙烷钝体熄火现象和规律进行研究。JL4的反应机理最简单，反应释热快，局部放热高，火焰宽度大，火焰两侧温度梯度大，燃烧更加趋于稳定，无法模拟出熄火状态。H73机理绝热火焰温度低，火焰温度低，回流区中部OH含量高；在近熄火状态，大量CO被氧化，释放热量过高导致无法模拟出熄火现象。Z66机理可以模拟出火焰正常状态，在低当量比下也可以模拟出熄火状态。本文算例中，局部Da数大于1的区域超过35%则会发生熄火。     

微纳聚合体卫星的对称式重构规划算法

为解决微纳聚合体卫星变构过程中，聚合体各部分之间的动力学耦合导致的卫星整体姿态翻转或紊乱，提出了一种对称式变构规划算法。首先建立了铰链约束下的漂浮基多刚体系统动力学模型，研究了重构过程中各运动模块对本体姿态的影响，提出当每两个运动模块位置与转动方向满足对称性条件时，两者对本体姿态的影响可在一定程度上相互抵消。基于上述理论，在A*算法中引入最优分配度量和对称性判定，设计了并行对称重构规划算法。仿真结果表明，该规划算法可实现重构过程中多模块并行、对称运动，重构过程总步数较少，运动模块对本体姿态的影响小。     

整体壳段典型特征高效模块化编程技术

整体壳段为航天产品核心零部件，具有结构复杂、尺寸精度高、材料去除率大、工艺过程复杂、加工周期长等特点。在壳段数控加工过程中，存在编程难度大、重复工作量大、效率低及编程质量与编程人员能力水平密切相关等问题。为了适应高效、高可靠性的任务需求，依托成熟商用CAM软件，通过对整体壳段典型特征的分析，基于UG NX软件平台研究并开发了典型特征自动化编程模块，有效提高了加工程序的质量稳定性，并极大降低了工艺人员的编程操作量，提高了工艺设计效率。     

一种小天体旋转参数估计方法

小天体旋转参数是科学数据，也是小天体测绘，着陆导航的基础数据.研究一种在小天体探测接近段过程中使用的基于图像上特征点跟踪和扩展卡尔曼滤波器的小天体旋转参数估计方法.该方法首先建立小天体旋转关系模型，表示小天体在相机坐标系中的姿态变化；然后定义小天体旋转的状态方程，推到了扩展卡尔曼滤波器的计算过程.通过对观测图像序列上的特征点跟踪，利用扩展卡尔曼滤波器方法得到小天体旋转轴指向和自转角速度估计.实验中，在仿真相机与小天体相机100 km距离上，分析了相机坐标系小天体坐标系之间的四元数初值，图像上特征点跟踪精度，相机的观测指向等因素对小天体旋转参数估计精度的影响.实验结果表明，提出的基于图像特征点跟踪和扩展卡尔曼滤波器的小天体旋转参数估计方法能够得到具有较高精度的估计结果.     

折叠式变体飞行器轨迹优化及控制分析

针对临近空间高超声速飞行器存在的问题，设计了一种折叠翼飞行器，可以通过折叠机翼来适应各种飞行状态，保持最优的气动特性。并针对临近空间滑翔式高超声速的特点，采用高斯伪谱法对固定翼飞行器和折叠翼飞行器的轨迹优化，通过将折叠翼飞行器与传统固定翼飞行器在射程能力、规避热流能力方面进行对比，提出了一种综合目标的轨迹优化思想。设计的折叠翼飞行器相比传统固定翼飞行器性能更加优越，更适合临近空间环境，提高了17.67%的航程，减少了热流率峰值的35.72%，并通过控制系统的设计和仿真加以验证，仿真结果表明变体飞行器机动能力相比固定翼飞行器有了显著的提高。     

基于混杂非对称复合材料的自适应对日定向器

提出并设计了一种基于混杂非对称复合材料层合板的新型自适应对日定向器。该对日定向器采用混杂非对称复合材料层合板作为驱动元件，利用在轨光照条件的变化引起复合材料层合板温度变化，进而使其产生热变形并驱动太阳翼发生偏转。提出的自适应对日定向器结合传统的单自由度对日定向机构，能够实现太阳能帆板的双自由度对日定向。介绍了自适应对日定向器的基本原理，并结合地球静止轨道的光照条件进行了具体设计。利用能量变分原理建立了混杂非对称复合材料的热变形模型，分析其热变形特点，并利用有限元方法对定向器在地球静止轨道上的温度场特性、热变形及对日定向转动角度进行分析。有限元分析结果表明，通过合理设计，自适应对日定向器的转角能够随太阳光入射角变化呈线性变化，定向精度可达±1°。     

Sliding mode control design for oblique wing aircraft in wing skewing process

When the wing of Oblique Wing Aircraft (OWA) is skewed, the center of gravity, inertia and aerodynamic characteristics of the aircraft all significantly change, causing an undesirable flight dynamic response, affecting the flying qualities, and even endangering the flight safety. In this study, the dynamic response of an OWA in the wing skewing process is simulated, showing that the three-axis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing. As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration, the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy. Given the properties of pitch-roll-yaw coupling and control input and state coupling, and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force, a multi-loop sliding mode controller is formulated by the time-scale separation method. The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable, which means that a smooth transition is obtained during the OWA’s wing skewing.     

Numerical analysis and optimization of boundary layer suction on airfoils

Numerical approach of hybrid laminar flow control(HLFC) is investigated for the suction hole with a width between 0.5 mm and 7 mm. The accuracy of Menter and Langtry’s transition model applied for simulating the flow with boundary layer suction is validated. The experiment data are compared with the computational results. The solutions show that this transition model can predict the transition position with suction control accurately. A well designed laminar airfoil is selected in the present research. For suction control with a single hole, the physical mechanism of suction control, including the impact of suction coefficient and the width and position of the suction hole on control results, is analyzed. The single hole simulation results indicate that it is favorable for transition delay and drag reduction to increase the suction coefficient and set the hole position closer to the trailing edge properly. The modified radial basis function(RBF) neural network and the modified differential evolution algorithm are used to optimize the design for suction control with three holes. The design variables are suction coefficient, hole width, hole position and hole spacing. The optimization target is to obtain the minimum drag coefficient. After optimization,the transition delay can be up to 17% and the aerodynamic drag coefficient can decrease by 12.1%.     

Flow separation control on swept wing with nanosecond pulse driven DBD plasma actuators

A 15° swept wing with dielectric barrier discharge plasma actuator is designed.Experimental study of flow separation control with nanosecond pulsed plasma actuation is performed at flow velocity up to 40 m/s. The effects of the actuation frequency and voltage on the aerodynamic performance of the swept wing are evaluated by the balanced force and pressure measurements in the wind tunnel. At last, the performances on separation flow control of the three types of actuators with plane and saw-toothed exposed electrodes are compared. The optimal actuation frequency for the flow separation control on the swept wing is detected, namely the reduced frequency is 0.775, which is different from 2-D airfoil separation control. There exists a threshold voltage for the low swept wing flow control. Before the threshold voltage, as the actuation voltage increases, the control effects become better. The maximum lift is increased by 23.1% with the drag decreased by 22.4% at 14°, compared with the base line. However, the best effects are obtained on actuator with plane exposed electrode in the low-speed experiment and the abilities of saw-toothed actuators are expected to be verified under high-speed conditions.     

三维数模随动下的机翼结构重量优化

目前,基于快速建模下的重量重心估算系统得到了快速发展。为了进一步提高结构重量估算精度,研究了如何在重量重心快速分析(WCGA)系统环境中构建优化模块。以机翼结构重量优化为例,提出优化流程,对优化模块功能进行分解,给出模型简化要求。以A320飞机机翼为例,对梁和长桁进行优化,结果显示,经过优化,有效减轻了结构重量,且相比于传统的减重优化设计方法,极大提高了计算效率。