针栓式喷注单元膜束撞击雾化混合过程数值模拟

为了全面认识针栓式喷注器喷雾场结构，基于自适应网格加密技术和分三相计算的PLIC VOF（Piecewise Linear Interface Calculation Volume of Fluid）方法对针栓式喷注单元膜束撞击雾化混合过程进行了仿真分析，通过对两路推进剂分别进行界面追踪，获得了膜束撞击雾化混合过程的详细结构特征，与高速摄影试验结果定性定量对比均吻合较好，验证了数值方法的准确性。以此为基础对膜束撞击的喷雾场结构、撞击变形过程、流场涡结构、雾化破碎典型特征及破碎后的雾化混合分布特征进行了识别分析，结果表明：膜束撞击形成了液束未穿透液膜和液束穿透液膜2种不同的喷雾扇结构。膜束撞击形成的喷雾扇呈"Ω"形，膜束同时发生弯曲变形和横截面变形。另外，膜束撞击同时受到正压和剪切应力作用，导致了一系列复杂涡流现象，使得相互作用增强，雾化混合均增强，这也是膜束撞击喷注构型优于膜膜撞击的本质原因。最后，还发现膜束撞击喷雾场液滴分布呈现分区结构特征，分别是液束控制主导的上雾化区、液膜控制主导的下雾化区及夹在中间的混合区，实际中应兼顾雾化特性和混合特性，选取中等动量比膜束撞击，这可为针栓式喷注器的理论研究和工程设计提供重要参考。     

ANALYSIS OF SHEAR STRESS DISTRIBUTION IN HONEYCOMB AIRCRAFT WING STRUCTURE SUBJECTED TO (S.T.) TORQUE

ＡＮＡＬＹＳＩＳＯＦＳＨＥＡＲＳＴＲＥＳＳＤＩＳＴＲＩＢＵＴＩＯＮＩＮＨＯＮＥＹＣＯＭＢＡＩＲＣＲＡＦＴＷＩＮＧＳＴＲＵＣＴＵＲＥＳＵＢＪＥＣＴＥＤＴＯ（Ｓ．Ｔ．）ＴＯＲＱＵＥＫｈａｌｉｄＭ．Ｔａｈｉｒ，ＺｈａｎｇＸｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＦ...     

浅析现代战斗机翼-身接头的构造和连接形式

较详细分析了现代战斗机翼-身接头的构造和连接形式以及各种形式的优缺点和选择这些结构形式时的注意事项,并对现代战斗机翼-身接头形式未来的发展趋势作出预测。     

Shear Flow Instabilities in Low-Beta Space Plasmas

We study instabilities driven by a sheared plasma flow in the low-frequency domain. Two unstable branches are found: the ion-sound mode and the kinetic Alfvén mode. Both instabilities are aperiodic. The ion-sound instability does not depend on the plasma β (gas/magnetic pressure ratio) and has a maximum growth rate of about 0.1 of the velocity gradient dV ₀/dx. On the other hand, the kinetic Alfvén instability is stronger for larger β and dominates the ion-sound instability for β > 0.05. Possible applications for space plasmas are shortly discussed.     

中纬突发E层特性的模拟分析

从基本的连续性方程出发，并结合运动方程，运用特征线方法求解，在合理的动力学假设条件下，模拟金属离子的汇聚，即Es层的形成．模拟的结果在一定程度上证实了风剪切理论的合理性．通过改变风场和电场模式的输入参量，使模拟的结果体现出不同当地时、不同季节的金属离子汇聚情况，讨论了模拟Es层峰值密度对风场和电场的周日和季节变化的响应，其结果与统计得到的Es层出现率的时间分布特征相似．     

平板表面薄圆柱绕流摩擦力矢量场全局测量

针对壁面摩擦力矢量场测量问题,基于剪切敏感液晶(SSLC)涂层技术建立了一种测量平板表面摩擦力矢量场的方法。该方法基于多视角测量原理,采用六台同步相机从不同方向同时采集SSLC涂层在摩擦力作用下的颜色变化,与采用单台相机相比能够降低测量噪声,并且具有测量非定常流动的摩擦力场的潜力。应用该方法测量了平板表面薄圆柱绕流的摩擦力矢量场,结果表明:(1)SSLC涂层能够以彩色方式定性显示壁面摩擦力信息;(2)通过对不同方向观测的SSLC涂层颜色进行分析处理,该方法能够高分辨率测量薄圆柱绕流的摩擦力矢量场,详细地捕获了流动特征;(3)同一份SSLC涂层可以重复使用并且可用于测量不同的摩擦力矢量场。     

Coronal Heating by Magnetic Explosions

From magnetic fields and coronal heating observed in flares, active regions, quiet regions, and coronal holes, we propose that exploding sheared core magnetic fields are the drivers of most of the dynamics and heating of the solar atmosphere, ranging from the largest and most powerful coronal mass ejections and flares, to the vigorous microflaring and coronal heating in active regions, to a multitude of fine-scale explosive events in the magnetic network, driving microflares, spicules, global coronal heating, and, consequently, the solar wind. This revised version was published online in June 2006 with corrections to the Cover Date.     

用织女一号火箭在海南站探测的高空风和风切变

本文介绍了织女一号(ZN-l)火箭测风原理,数据处理方法和两次测风结果.结果指出,在我国低纬地区中层大气中存在非常明显的风切变和相当强的重力波扰动,测风数据与COSPAR国际参考大气CIRA1986及国际标准化组织航空用参考大气ISO5878-1982／ADD.1-1983存在明显差别.      

无头铆钉成型过程的有限元仿真与试验分析

采用ABAQUS建立有限元分析模型,分析了66°锥形铆模压铆无头铆钉的成型过程。对成型后的试片进行了力学及金相分析,并将结果与普通半圆头铆钉进行对比。研究结果表明,无头铆钉的压铆变形过程为钉杆中间最早涨粗,墩头部分成型,随后钉杆部分逐步与孔壁均匀挤压的过程;随着压铆位移的增加,无头铆钉拉脱强度及剪切强度均呈上升趋势;与传统平铆模成型的半圆头铆钉相比,在锥形铆模的作用下,金属材料向钉杆流动更加均匀,墩头两侧的绝热剪切效应明显弱化。     

Periodic atomization characteristics of an impinging jet injector element modulated by Klystron effect

An experimental study on the Klystron effect of periodic injection modulated by pressure drop fluctuations on subsequent atomization is conducted. Time-resolved atomization backlit images and atomization Mie scatter images are captured by using the high speed camera. It is found that periodicity of forced atomization relies on pressure drop fluctuation amplitude and phase differences between atomization and pressure drop fluctuations relate to fluctuation frequencies. This feature of periodic atomization induced by Klystron effect corresponds to periodicities and high amplitudes of pressure fluctuations in unstable combustion chambers and chaos and low amplitudes of pressure fluctuations in stable combustions chambers. Drastically periodic varying of gross surface area of droplets with time was shown in Mie scatter images. The importance of periodic impinging jet atomization modulated by pressure drop fluctuations for acoustic liquid propellant combustion instabilities is illustrated.