训练中齐射尾流自导鱼雷碰撞问题及对策

为满足当前潜艇部队训练的需要，针对尾流自导鱼雷齐射训练中可能出现的碰撞问题，以鱼雷散布为基础，分别对齐射时鱼雷进入尾流前发生碰撞，鱼雷过目标舰时与目标舰发生擦碰以及双雷齐射时两雷进入目标尾流后双雷碰撞的3种可能发生的情况进行分析，提出了采用两雷齐射时，设定1条雷的”操雷航程”，以避免两雷交叉，对两雷设定不同”海况”，使两雷航行在不同深度以及两雷反方向发射等避免碰撞的修正方法。该方法易于操作，可为尾流自导鱼雷安全训练提供有效保证。     

有可能用于鱼雷尾流自导的某些光学特征

介绍了尾流自导鱼雷特点,研究了真实尾流的光学特性,提出了用于鱼雷尾流自导可能的光学特征。     

Origin of the negative wake behind a bubble rising in non-Newtonian fluids

The present work aims at understanding the behavior of individual bubbles in non-Newtonian fluids. By means of a Particle Image Velocimetry (PIV) device, the complete flow field around either a single non-spherical bubble rising in polyacrylamide (PAAm) solutions or a solid sphere settling down in the same fluids shows for the first time the similar coexistence of three distinct zones: a central downward flow behind the bubble or the sphere (negative wake), a conical upward flow surrounding the negative wake zone, and an upward flow zone in front of the bubble or the sphere. This excludes then the possible influence of the interface deformation on the negative wake. A theoretical lattice Boltzmann scheme coupled to a sixth-order Maxwell model was developed for computing the complex flow field around a solid sphere. The good agreement with the experimental measurements provides evidence that the physical mechanism responsible for the negative wake in such fluids could be related to the fluid's viscoelastic properties.     

排桩式波浪能发电装置附近流场特性研究

基于雷诺时均Navier-Stokes方程和k?ω湍流模型,研究单排桩式振荡水柱式波浪能发电装置在规则波作用下的桩基附近流场特性. 通过物理模型实验验证所建数值波浪水槽的准确性. 模拟规则波作用下装置附近的流场特性,分析装置附近的涡特征以及其对装置附近泥沙冲刷情况的潜在影响. 结果表明,测试工况下,在桩式振荡水柱装置桩柱体的桩基附近观察到马蹄涡和尾涡现象,马蹄涡强度随着Keulegan–Carpenter（KC）数的增大而减小,尾涡强度随着KC数的增大而增大. 马蹄涡因强度过小,在模拟的KC数范围内不是装置桩基泥沙冲刷的主要因素,高强度的尾涡很可能成为装置桩基附近泥沙起动、输运和冲刷的重要影响因素.     

基于Hough变换的SAR图像舰船尾迹检测方法

该文提出了一种基于Hough变换与K均值聚类检测舰船尾迹的算法。该方法通过归一化Hough变换求出原图像尾迹所在直线的平均能量值,由于原图中的尾迹往往并不规则,导致能量最大值并不是整条直线的最佳统计代表值,其周围会有一些能量次大的点出现,且形成一个由若干能量点组成的点集。该文引进了K均值聚类方法,将这些点集归类,归类后的每一类的类心能很好的代表一条尾迹,实验结果表明方法是有效的。     

New explicit algebraic stress and flux model for active scalar and simulation of shear stratified cylinder wake flow

On the numerical simulation of active scalar, a new explicit algebraic expression on active scalar flux was derived based on Wikstr?m, Wallin and Johansson model (a ^WWJ model). Reynolds stress algebraic expressions were added by a term to account for the buoyancy effect. The new explicit Reynolds stress and active scalar flux model was then established. Governing equations of this model were solved by finite volume method with unstructured grids. The thermal shear stratified cylinder wake flow was computed by this new model. The computational results are in good agreement with laboratorial measurements. This work is the development on modeling of explicit algebraic Reynolds stress and scalar flux, and is also a further modification of the a ^WWJ model for complex situations such as a shear stratified flow. Supported by the National Nature Science Foundation of China (Grant Nos. 50679019, 50009001), the National Basic Research Program of China (“973” Project) (Grant No. 2008CB418202), the Project of “Six Talent Peak” of Jiangsu Province (08-C), Social Technology Development Foundation of Jiangsu Province (Grant No. BS2006095) and the “908” Special Foundation of Jiangsu Province (Grant No. JS-908-02-06)     

基于CC1100的无线抄表系统

介绍了一种利用单片机和CC1100无线通讯芯片构成的无线抄表系统,叙述了工作原理和实现过程,并重点介绍了CC1100的电磁波唤醒功能和原理,给出了详细的结论.     

Upstream wake-secondary flow interactions in the endwall region of high-loaded turbines

A detailed experimental and numerical investigation of the unsteady interaction of secondary flow vortices in turbine endwall region was performed with the effect of upstream periodic wakes. The flow field was investigated respectively in a linear turbine cascade and a turbine rotor. The study revealed the physical mechanisms of unsteady interaction between upstream wake and secondary vortices. The influence of the upstream wake on the performance of turbine endwall region was also discussed.The flow field at the exit of the turbine blade row showed a decrease in passage vortex strength and loss due to the upstream wake transport. Two interaction mechanisms are proposed whereby passage vortex loss decreases. They are the upstream wake-pressure side leg of the horseshoe vortex interaction and the upstream wake-passage vortex interaction. The transport of upstream wake can suppress the development of pressure side leg of the horseshoe vortex and passage vortex because of the “negative jet” influence of the wake.     

基于粒子系统的火箭尾焰实时模拟

提高虚拟火箭飞行的真实性,火箭尾焰的实时模拟是关键;在对火箭尾焰的静动态特性进行分析的基础上,建立了火箭尾焰的粒子运动模型,实时模拟了火箭尾焰;在建模过程中采用了面片贴图作为粒子体素的方法以简化模型,并通过相应算法,将面片法向量与观察视线的夹角维持在恒定的范围内,保证了观察效果,提高了粒子体素利用率;应用该方法在火箭飞行仿真中模拟火箭尾焰,粒子量少,逼真度高,较好地解决了视景仿真过程中实时性和逼真度的矛盾,证明了方法的可用性。     

尾板对重型载货汽车尾部流场的影响

为了降低风的阻力,对某牵引式重型载货汽车加装了4种不同形式和尺寸的尾板。并采用数值仿真的方法分析了尾板对流场的影响,探索了风阻产生机理和降低原因。仿真工况模拟正常车辆行驶速度25m/s,未考虑侧风影响。计算结果表明:安装4种尾板后风阻系数均有降低,降幅最大为2.8%,获得了较满意的降阻效果。对比分析了4种方案的整车气动阻力系数、流速分布及总压为零等值面的计算结果。研究发现:尾板对车身周围气流的影响集中在货箱尾部,改变了尾流中原有的环形漩涡结构,从而降低了风阻。