放宽静稳定性在空空导弹总体设计中的应用

将主动控制技术引入空空导弹总体设计中，研究了空空导弹放宽静稳定性设计问题，讨论了放宽静稳定性设计对导弹性能的改善，最后给出了静不稳定弹体的系统稳定性判定条件，并着重讨论了静不稳定弹体的人工稳定问题，研究结果对于新一代先进空空导弹的总体设计工作有一定的参考价值。     

二维平行剪切层声波产生和辐射的数值模拟

 在二维线化Euler 方程的基础上解决了第3 届计算气动声学专题讨论会的第5 类标准问题: 二维平行剪切层声波的产生和辐射。频散相关保持有限差分格式用于空间离散, 低频散低耗散的龙格库塔法用于时间积分。重点使用了远场无反射边界条件。计算结果与NASA GLENN 研究中心的解析解符合得很好。     

The Full Flowpath Analysis of a Hypersonic Vehicle

对一种类X43-A吸气式高超飞行器全流道开展了M7一级的三维数值仿真研究,深入探索了进气道处于起动状态和不起动状态时全流道的冷流流场结构和和气动力特性,且部分结果与实验数据进行了对比。研究结果表明:(1)前体横截面上存在显著的展向压强梯度,使得经过预压缩的气流偏离了进气道进口,但同时也减少了进入内通道的边界层气流,提高了进口流场的品质;(2)后体喷流股的膨胀过程受到了周围外流的显著干扰,因而沿流动方向其截面形状不断发生变化,如在喷口附近为近似矩形,而在后体末端附近则演化为近似三角形;(3)当进气道处于不起动状态时,其全流道流动结构发生了显著变化,进气道的外部压缩波系往复振荡,尾喷管出口的喷流股也在不停的膨胀和收缩,具有极强的非定常特征;(4)当进气道处于不起动状态时,全机的气动力特性呈周期性变化,升阻比的变化幅度较大,在最大、最小值分别可达起动状态的2倍和1/4倍。另外,升力、阻力系数的变化曲线之间存在一定的相位差;(5)与实验结果的对照表明,所采用的数值仿真方法具有较高的精度。     

大功率高频无线电波对赤道E区双流不稳定性的影响--PIC静电粒子模拟研究

地面入射的大功率高频无线电波(泵波)和电离层等离子体之间的参数相互作用，能够引起静电波的激发，在一定条件下，产生不稳定性．本文用PIC静电粒子模拟方法，研究泵波与赤道电离层E区等离子体的相互作用．研究结果表明，泵波能够控制双流不稳定性的发生，在不同条件下，泵波对双流不稳定性起着稳定与不稳作用，模拟结果定性地与理论研究结果相符合，这为我们对不规则体产生的地面人工控制提供了依据．     

成形极限曲线（FLC）的新概念

失稳理论是FLC的理论基础。文章论述了FLC理论研究中存在的问题。指出:一般出厂板的表面状况不会影响板料的集中失稳;板内损伤平面应变时最严重。双拉时,板内损伤的积累、发展,导致应力状态向平面应变漂移;拉压时,载荷失稳后引起的双拉,也会导致平面应变。因此平面应变状态的出现是板料集中失稳的共同原因。在此基础上提出了建立FLC的统一的模型。     

Hydrodynamic instabilities and transverse waves in propagation mechanism of gaseous detonations

The present study examines the role of transverse waves and hydrodynamic instabilities mainly, Richtmyer–Meshkov instability (RMI) and Kelvin–Helmholtz instability (KHI) in detonation structure using two-dimensional high-resolution numerical simulations of Euler equations. To compare the numerical results with those of experiments, Navier–Stokes simulations are also performed by utilizing the effect of diffusion in highly irregular detonations. Results for both moderate and low activation energy mixtures reveal that upon collision of two triple points a pair of forward and backward facing jets is formed. As the jets spread, they undergo Richtmyer–Meshkov instability. The drastic growth of the forward jet found to have profound role in re-acceleration of the detonation wave at the end of a detonation cell cycle. For irregular detonations, the transverse waves found to have substantial role in propagation mechanism of such detonations. In regular detonations, the lead shock ignites all the gases passing through it, hence, the transverse waves and hydrodynamic instabilities do not play crucial role in propagation mechanism of such regular detonations. In comparison with previous numerical simulations present simulation using single-step kinetics shows a distinct keystone-shaped region at the end of the detonation cell.     

Heliopause stability revisited: dispersion analysis and numerical simulations

The heliopause, a surface separating the tenuous hot heliosheath flow and the dense, strongly magnetized interstellar flow, is subject to instabilities of the Rayleigh–Taylor and Kelvin–Helmholtz types. The dynamic evolution of this discontinuity is of considerable importance for understanding the neutral atom and cosmic-ray filtration at the interface. Here, we investigate the stability of the upwind heliopause in the presence of charge exchange collisions using both an analytic (dispersion relation) approach and a numerical model that includes the interstellar magnetic field. The linear analysis yields a cubic dispersion relation that admits imaginary solutions for the full range of wavenumbers, implying that the stagnation point on the heliopause is unconditionally Rayleigh–Taylor unstable to small perturbations propagating parallel to the discontinuity surface. We confirm this result by following the nonlinear development of the instability with a time-dependent simulation using a four fluid MHD-neutral numerical code. For the typical solar wind and LISM conditions, we obtain cyclical evolution of the upwind heliopause with a period of the order of 100 years. We also identify two areas of space physics where the instability may have important implications.     

振荡环境下推进剂液滴亚临界蒸发响应特性

针对推进剂液滴在惰性气体中的蒸发过程建立了非定常物理模型,并应用全隐差分格式离散模型方程进行数值求解。研究了液滴蒸发过程对环境气体压力振荡的响应特性,可为液体火箭发动机不稳定燃烧分析提供理论基础。      

某涡喷发动机压气机气动失稳过程的非线性分析

对某涡喷发动机压气机的气动失稳过程进行了相关积分分析。对节流过程中压气机静压信号进行延时嵌入重构,发现失稳过程中重构相空间的吸引子结构发生了显著变化;应用相关积分值作为压气机内部流动状况变化的评价指标,发现节流过程中压气机第1级端部的流动最先发生不稳定,随后第2级先于第3,4级发生不稳定征兆;1,2级的失速类型为渐进型失速,3,4级为突变型失速;第3级叶根最先发生不稳定,且发展较快,最终导致全叶高失速;低通滤波可以提高相关积分方法检测失速征兆的时效性。分析表明,非线性的相关积分分析方法是进行压气机气动失稳过程研究的有效手段。      

A high-order model of rotating stall in axial compressors with inlet distortion

In this paper,a high-order distortion model is proposed for analyzing the rotating stall inception process induced by inlet distortion in axial compressors.A distortion-generating screen in the compressor inlet is considered.By assuming a quadratic function for the local flow total pressure-drop,the existing Mansoux model is extended to include the effects of static inlet distor tion,and a new high-order distortion model is derived.To illustrate the effectiveness of the distortion model,numerical simulations are performed on an eighteenth-order model.It is demonstrated that long length-scale disturbances emerge out of the distorted background flow,and further induce the onset of rotating stall in advance.In addition,the circumferential non-uniform distribution and time evolution of the axial flow are also shown to be consistent with the existing features.It is thus shown that the high-order distortion model is capable of describing the transient behavior of stall inception and will contribute further to stall detection under inlet distortion.