高超声速风洞变雷诺数试验技术研究

为满足高超声速飞行器气动力雷诺数效应研究需求,在CARDC的Φ1米高超声速风洞中开展了变雷诺数试验技术研究.该项试验技术是利用Φ1米高超声速风洞采用高压下吹-真空抽吸驱动运行方式、风洞运行参数范围宽的特点,通过宽范围内调节风洞运行总压而大幅改变模拟雷诺数.研究采用了单点变雷诺数试验技术和连续变雷诺数试验技术两种手段来开展高超声速飞行器气动力雷诺数效应模拟.单点变雷诺数试验是通过一系列不同雷诺数条件、不同试验车次的试验结果,获得气动特性随雷诺数的变化规律;连续变雷诺数试验时,控制风洞总压从高到低连续变化,测量获取模型处于某一姿态角条件时气动力随雷诺数的变化规律.本文介绍了变雷诺数试验的风洞开车方式、试验及数据处理方法等,并开展了某升力体飞行器和某弹头模型雷诺数效应试验研究.研究结果表明:采用单点和连续变雷诺数试验技术相结合的方式,能较为完整、准确地获得飞行器模型气动力随雷诺数的变化规律.     

Key Parameters and Conceptual Configuration of Unmanned Combat Aerial Vehicle Concept

The nature and characteristics of attack unmanned combat aerial vehicle (UCAV) are analyzed. The principles of selecting takeoff thrust-weight ratio and takeoff weight of attack UCAV are presented by analyzing the statistical data of weights for various main combat aircraft. The UCAV airborne weapons are analyzed, followed by the preliminary estimation of the payload weight. Various typical engines are analyzed and one of them is selected. Then the takeoff weight of the UCAV is determined. Based on some basic parameters and assumptions, the qualitative decomposition calculation for takeoff weight is completed. The key factors for obtaining longer endurance of aircraft with small aspect ratio configuration are found to be high lift-drag ratio and internal space. On the basis of the conclusions mentioned above, a highly blended flying-wing plus lifting body concept is proposed. According to this concept, the UCAV configuration is designed and optimized. Finally, the UCAV configuration with small aspect ratio, high lift-drag ratio, and high stealth characteristic is obtained.     

运载火箭推力故障下在线计算轻量化任务重构方法

为了避免运载火箭推力下降故障引起发射任务失败,基于径向基神经网络,提出了一种在线计算轻量化的任务重构方法,可快速在线计算最优救援轨道对应飞行轨迹(最优轨迹)的近似解.在离线部分,结合凸优化与自适应配点法产生"故障状态-最优轨迹"数据集.数据集被用来训练径向基神经网络,建立轨迹决策模型来构建故障状态到最优轨迹的动力学关系...     

开环机构末杆自由度的对偶矢量解法

运用对偶矢量理论定量地分析开环机构中各运动副所容许的相对运动在末杆上的反映，通过计算末杆独立对偶对速度来确定末杆独立运动的数目，从而给出一种求解末杆自由度的方法     

A second-order numerical method for elliptic equations with singular sources using local flter

The presence of Dirac delta function in differential equation can lead to a discontinuity,which may degrade the accuracy of related numerical methods.To improve the accuracy,a secondorder numerical method for elliptic equations with singular sources is introduced by employing a local kernel flter.In this method,the discontinuous equation is convoluted with the kernel function to obtain a more regular one.Then the original equation is replaced by this fltered equation around the singular points,to obtain discrete numerical form.The unchanged equations at the other points are discretized by using a central difference scheme.1D and 2D examples are carried out to validate the correctness and accuracy of the present method.The results show that a second-order of accuracy can be obtained in the fltering framework with an appropriate integration rule.Furthermore,the present method does not need any jump condition,and also has extremely simple form that can be easily extended to high dimensional cases and complex geometry.     

绕振动旋成体的跨声速流数值分析

本文采用Ｅｕｌｅｒ方程和ＴＶＤ格式数值求解了小幅振动旋成体的非定常跨声速绕流问题，，假设在绕小幅振旋成体的非定常气流中，物理量的变化为平均定常扰动物理量的高阶小量，然后对Ｅｕｌｅｒ方程进行摄动展开，导出前两阶（零阶及一阶）摄动量的控制方程和相庆的边界条件，并进行数值求解。文中仅给出了振动旋成体的非定常压力分布。     

头部旋转对细长体大迎角不对称涡系影响机理的实验研究

本文介绍了头部旋转对大迎角不对称涡系影响的观测结果,说明了由此而抑制大迎角不对称涡系的机理。 实验结果表明,头部旋转对细长体无侧滑大迎角不对称涡系涡迹的影响是:随头部的逐渐转动,涡系的不对称发生了周期性变化;此时,由于涡不可能迅速改变状态,从而抑制、甚至接近消除了大迎角时出现的涡系不对称现象。     

非定常气动力对飞机飞行影响的拓扑分析

 根据飞机六自由度运动模型和微分非定常气动力模型, 计算了周期轨道及平衡运动的拓扑结构图,初步研究了非定常气动力对飞机飞行的全局影响, 并通过系统的导算子矩阵根轨迹、时域仿真及其灵敏度分析, 提炼出非定常气动力对飞机飞行影响的初步机理。结果表明, 非定常气动力对飞机平衡运动的振荡不稳影响明显, 可以改变其稳定特性, 延迟Ho pf 分叉的出现。对于稳定的周期运动, 由于增加了系统的阻尼耗散项从而减少了振荡幅度。     

解不可压N—S方程的PCIMG法

本文提出了一种解不可压N-S方程的预测、修正、迭代、多重网格法。这种算法程序简单,结果精确及收敛快速。     

快速上仰翼型的非定常前缘分离研究

 近几年,国外对翼型快速上仰运动进行了许多实验和理论研究,最大迎角可达60°以上,目的是探索如何利用由此产生的非常大的非定常气动力（如战斗机的超机动飞行）。研究的重点放在“动力失速问题”上,这时,称之为“动力失速涡”的“前缘涡”早已形成并向下游推移。但是,至今动力失速的确切原因和过程仍未被很好地了解。