纤维织物超高速碰撞热-力学模型与分析

A new thermo mechanical model for fiber fabric of hypervelocity impact is established by using the Johnson Cook model, the Gruneisen equation of state and the FEM SPH coupling algorithm, while some new factors are taken into account such as the heat generation, strain rate strengthening and high temperature softening of materials. Mechanical and thermal information could be obtained with the model, such as penetration, fragmentation, stress and strain, heat generation and temperature field of fiber fabric. The analysis results are in good agreement with the experimental results.     

夜气辉对天基光学碎片探测的影响分析

设计并完成了夜气辉背景下的天基碎片观测试验，获取了综合谱段的观测数据。基于观测数据进行夜气辉的辐射特性及其对天基碎片探测的影响分析。结果表明，夜气辉辐射随纬度和高度呈现一定的分布特点，这些特点均符合夜气辉的理论分布规律。在约90 km处辐射最强，亮度可达到单位积分时间每平方角秒近15星等，这对恒星及碎片提取概率影响较大，其中，13等星的提取概率仅为40.5%。     

碳纳米管阵列推力器放电特性的数值模拟研究

基于直接蒙特卡洛(DSMC)算法、浸入式有限元算法(IFE)、粒子云及蒙特卡洛碰撞(PIC-MCC)算法以及Ammosov-Delone-Krainov(ADK)隧穿电离模型建立了碳纳米管阵列推力器工质气体和CNT场电离过程的三维仿真模型。利用文献中的实验数据对本文仿真模型的有效性进行了验证,结果表明本文仿真模型与实验结果基本一致。针对碳纳米管阵列推力器的放电特性进行了研究,并重点分析了离子与原子碰撞过程对碳纳米管阵列推力器放电特性的影响。结果表明CNT可以极大地增强局部电场,稳态时场增强因子约为1308;与原子的碰撞使得离子在CNT附近更加集中,降低了局部电场,进而降低了其场增强能力。     

基于新陈代谢GM（1,1）模型的导弹遥测故障预测算法

在人工监视遥测关键参数是否超出阈值范围以判断导弹故障的传统模式基础上,对GM（1,1）预测模型进行了改进,研究了基于新陈代谢的GM（1,1）预测算法对遥测参数实时预测效果.该算法能不断去掉最老的信息,充分利用最新的信息,避免了预测模型老化的现象;由于用于预测的数列维度较少,便于计算,能够保证算法的实时性.用MATLAB编程实现算法,比对实测数据的预测值与实际值,并进行误差分析.结果表明,该算法对遥测参数的预测精度较高,可为及时发现导弹故障提供科学的依据.     

一种用于二维燃烧室流场计算的非结构网格的生成方法

本文依照Ｄｅｌａｕｎａｙ 准则构造二维非结构网格,并提出了一种与之相应的基于阵面推进法的自动生成新的内部节点的方法。文中给出了利用这一方法对边界形状复杂的燃烧室流场进行网格划分时,所得的非结构网格,及网格相应的质量统计特性。从这些算例可以看出,这一方法能够较好地适应复杂的几何外形,得到分布合理,并且大多数单元形状接近正三角形的非结构网格     

用于风洞实验的磁悬挂技术研究

30mm×30mm五分力磁悬挂天平由电磁铁组、电磁感应式位置传感器、磁悬挂控制器、气动力测量系统等部分构成。在80m/s低速风洞中进行了吹风试验的主要结果,包括电磁铁设计理论与结构形状、传感器工作原理与数学模型、控制补偿律和工程实现中的一些技术问题。     

一种新的鲁棒非线性卡尔曼滤波

Huber方法是一种基于l1/l2联合范数的估计方法,该方法可以实现估计的鲁棒性,同时尽量不损失滤波精度和效率.基于Huber估计的无味卡尔曼滤波虽提高了无味卡尔曼滤波的鲁棒性,但这种方法用统计线性回归模型来近似非线性的观测模型,损失了无味变换的精度.从Huber方法的数学意义出发,对观测信息(观测值或观测噪声)进行重新构造,然后对精确的非线性观测方程进行标准的无味卡尔曼滤波,这种新的基于Huber方法的无味卡尔曼滤波无需对非线性观测方程进行线性近似,在保持鲁棒性的前提下提高了滤波精度.通过一个具有混合高斯分布观测噪声的简明实例,验证了新算法在鲁棒性、滤波精度以及估计一致性方面的优势.     

Numerical investigation of the impact of asymmetric fuel injection on shock train characteristics

Numerical simulations are carried out to investigate the impact of asymmetric fuel injection on shock train characteristics using the commercial-code FLUENT. The asymmetry of fuel injection is examined by changing the fuel flow rates of the upper and lower wall fuel injectors. The numerical approach solves the two-dimensional Reynolds-averaged Navier–Stokes (RANS) equations, supplemented with a k-ω model of turbulence. As a result, different ways of fuel injections will always lead to shock train transitions, with the variations of shock train structure, strength and leading edge position. For symmetric fuel injection, the flowfield of the isolator is quite asymmetric with the boundary layer of the upper wall side developing much stronger than that of the lower wall, which is due to the heterogeneity of the incoming flow. Regarding to asymmetric fuel injection with more of lower wall side, though the pressures in the combustor are nearly the same, the first shock of the shock train converts between ‘Distinct symmetric X type shock’ and ‘Obscure and weaker asymmetric shock’ and the shock train leading edge moves upstream with the increase of the asymmetry level. With regard to asymmetric fuel injection with more of upper wall side, ‘incomplete asymmetric X type shock’ occurs and the shock train structures keep nearly the same with low level of fuel injection asymmetry. Unexpected results like unstart will happen when increasing the level of fuel injection asymmetry. And the isolator will come back to normal state by decreasing the differential of upper and lower wall sides fuel injections.     

Experimental study of a flush wall scramjet combustor equipped with strut/wall fuel injection

In this study a flush wall scramjet combustor is tested in a supersonic incoming air flow with the Mach number of 3 which is generated by an air vitiation heater producing the stagnation temperature of 1505 K. Using liquid kerosene as the fuel, the flame is stabilized by means of a centrally mounted O₂ pilot strut after being ignited by a plasma torch. During experimental measurements, the fuel is injected with a constant equivalence ratio of 0.8 according to specified strut/wall injection ratios, i.e., a portion of the fuel amount is injected from the strut while the rest is injected from the wall. The strut and wall injectors are arranged at the same axial position. The combustion performance and wall temperature gradients are evaluated with various fuel feeding ratios between the wall and the strut. Experimental results show, when the equivalence ratio is constant and the axial injection position is fixed, the combustion characteristics vary significantly with the strut/wall fuel feeding ratio, especially when this ratio is close to its lowest and highest limits. Among the four fuel feeding ratios examined, the strut only injection mode and the average distributed strut/wall injection mode show the best combustion performance. However, the strut/wall injection mode produces a smaller wall temperature gradient compared to the strut only injection mode, which is due to the significant film cooling effect caused by the wall injected liquid kerosene.