两相流PIV粒子图像处理方法的研究

本文在单相PIV技术的基础上研究了两相流动PIV图像处理方法，采用摸板匹配法和灰度加权标定法对两相粒子进行了识别、区分和标定，采用灰度互相关法对区分后的单相粒子图像进行了处理，应用基于以上方法编制的Windows应用软件，首先对由美国Minnesota大学复杂流动实验室提供的两相流动粒子图片进行了处理，通过对比分析可见，应用本文所采用的方法能对两相粒子进行有效的识别和区分，然后以搅拌槽内液固两相流场为例对此方法进行了应用。     

气液两相流中气泡运动速度场的PIV分析与研究

粒子图像测速技术（PIV）作为一种无扰、瞬态、全场速度测量方法，已被广泛应用于液体或气体的单相流流速场测定。对于两相流PIV技术，目前还处于起步阶段，本文应用PIV技术的基本原理，对静止液体中的气泡运动速度进行了分析，并对有关气液两相流测量问题进行了探讨。     

三维粒子成像测速（PIV）中粒子像斑定位的透视成像原理,方法及其可确定性

在三维粒子成像测速（ＰＩＶ）方面,可运用体积光照明同时从不同光轴用多个照相机获得ＰＩＶ图像,如何根据这些不同光轴获得的ＰＩＶ图像确定出粒子物点的空间位置是实现三维粒子成像测速的前提。基于此,本文提出了根据多幅不同光轴的ＰＩＶ图像的粒子像斑实现粒子物点三维定位的透视成像定位原理和方法,精确确定透视平面与透视中心在空间的位置是实现粒子物点三维定位的关键,直接测定透视中心（照相机的光学中心）和透视平面在     

基于BICC算法的PIV技术

对基于ＢＩＣＣ（ＢｉｎａｒｙＩｍａｇｅＣｒｏｓｓ－Ｃｏｒｒｅｌａｔｉｏｎ）算法的ＰＩＶ（ＰａｒｔｉｃｌｅＩｍａｇｅＶｅｌｏｃｉｍｅｔｒｙ）技术的原理进行了较详细的介绍．以封闭的正方形容器内的旋转流场为例，用计算机模拟检验了ＢＩＣＣ算法的可靠性，最后利用ＰＩＶ技术对阀腔内真实流场进行了测量．结果表明，ＢＩＣＣ算法能有效地进行图像粒子的识别，利用该算法可以得到精确的ＰＩＶ测量结果．     

用胶囊式液晶粒子同时测量流场的温度和速度

胆甾相液晶在不同温度下显示不同的颜色，这一特性已被广泛地应用于固体表面或流体的温度测量．胶囊式胆甾相液晶具有粒子形态和温度－颜色反应特性，可以用来同时测量流体的速度和温度场．作者改进了粒子测速的测试精度；还标定了色度－温度关系，获得了自然对流流场中的速度和温度场     

两相介质中火焰诱导激波现象的研究

基于双流体模型，采用跟踪法处理火焰内边界，ＴＶＤ格式计算气相激波，ＭａｃＣｏ－ｍａｃｋ格式计算颗粒相流场，对两相可燃介质中火焰诱导激波现象进行了理论分析与实验模拟，研究了颗粒相参数对火焰诱导激波现象的影响。     

强旋湍流气－固两相流动的颗粒随机轨道法模拟

应用颗粒随机轨道模型，并与一种新的代数Ｒｅｙｎｏｌｄｓ应力模型相结合，对新型煤粉涡旋燃烧炉内强旋湍流气。固两相流动进行了数值模拟。得到了与实验相符合的颗粒相密度分布和质量流分布。计算结果表明，在涡旋燃烧炉内的强旋湍流流场中，外壁附近颗粒浓度最高，颗粒停留时间加长，气－固两相间滑移速度增大。     

方管内气固两相流动速度的LDV测量

介绍了气固两相流动的ＬＤＶ测试方法和有关技术，并给出了方管内网栅后气固两相流动的部分测试结果与分析。对于气相，给出了纯净气流（α＝０）、平均粒径ｄｐ＝３５０μｍ的颗粒（α＝０．１２％、０．２１％、０．３３５％）存在时的气流在管内不同断面上时均速度分布情况及不同颗粒浓度时气流速度结构的比较；对于固相，给出了三种不同固相浓度时颗粒在管内不同断面上时均速度的分布情况，并对三种固相浓度时颗粒与气相的速度分布进行了比较。     

密相液固两相湍流流动研究

在ＩＰＳＡＲ算法基础上推导了适用于考虑液度变化影响的密相液固两相湍流流动数值计算的ＤＩＰＳＡＲ算法，并采用低雷诺数模型，对竖直上升管中密相液固两相湍流分别采用ＩＰＳＡＲ算法和ＤＩＰＳＡＲ算法进行了数值计算，计算值与实测值较符合，计算结果的比较表明ＤＩＰＳＡＲ算法能更有效地预测密相液固两相湍流流动     

旋转,弯曲,扩散流道中流固两相流场的数值模拟及其分析

本文简要介绍了旋转,弯曲,扩散流道中,液－固两相流流数值计算结果,进而从理论上分析了泵叶轮压力面遭受磨损和输送两相流时扬程度降低的原因。     

Particle dispersion in a single-sided backward-facing step flow

The paper describes the particle dispersion in a single-sided backward-facing step flow. Particles of well-known sizes in the diameter range from 1 to 70 μm were suspended in an air flow and the particle motion over a step was measured by mean of a laser-Doppler anemometer. Thus, the local and integral flow quantities, i.e. the mean and turbulent velocity data could be measured precisely. In the experiments, monodispersed particle size distributions were used to exclude particle size related information ambiguity, known as triggering effects or size bias. The results of this study show qualitatively and quantitatively the difference in time-averaged particle dynamics for selected particle sizes in a backward-facing step flow. The experiments show, for different sizes, the changes in the particle velocity field in comparison with the velocity field of the continuous phase deduced from the 1 μm particles, and also imply the strong influences which different particle sizes have on flow data evaluation when size effects are not taken into account with particle-related optical measuring techniques.     

气固两相分支管流动及流量分配特性的研究

在水平T型分支管道中,用压缩空气对平均粒径为0．5mm砂石进行气固两相流试验。试验结果表明,当压缩空气的流速大于33m／s时,T型分支接头处没有固相沉积,两个分支管路分配的流量几乎相同。当压缩空气的流速小于33m／s时,分支接头处出现沉积,并且沉积量和分支管路的流量分配与分支管路上阀门开度有关:开度相同时,分支接头两侧的固相沉积量和流量分配相同;开度不同时,阀门开度小的一侧分支接头处的沉积量少,其分配的流量也少。     

The flow structure of dilute gas-particle suspensions behind a shock wave moving along a flat surface

The asymptotic and numerical investigations of shock-induced boundary layers in gas-particle mixtures are presented.The Saffman lift force acting on a particle in a shear flow istaken into account.It is shown that particle migration across the boundary layer leads tointersections of particle trajectories.The corresponding modification of dusty gas model isproposed in this paper.The equations of two-phase sidewall boundary layer behind a shock wave moving at aconstant speed are obtained by using the method of matched asymptotic expansions.Themethod of the calculation of particle phase parameters in Lagrangian coordinates isdescribed in detail.Some numerical results for the case of small particle concentration aregiven.     

气泡-水流两相流的激光多普勒法测量

为区分激光多普勒稀态两相流动测量中出现的流体相信号和颗粒(气泡、液滴)相信号,本文提出可见度和基座的复合判别法,并设计了专用的信号预处理器,此预处理器能将原始多普勒信号分为两路,分别代表两相,并可用计数型信号处理器测量每路的速度及其它统计量。使用本方案对矩形管道內低速气泡-水两相流的实验和测量表明,对两相的区分和测量是成功的。文中给出了两相速度、湍流度和气泡滑移速度的测量结果。     

悬浮RDX炸药和铝颗粒混合粉尘爆轰的数值模拟

采用两相流方法对炸药颗粒直径为20.0 m时与铝颗粒混合物的爆轰波的发展与传播过程及爆轰波参数进行了数值计算。结果表明,在炸药粉尘中加入铝颗粒,可以大大提高爆轰波参数。当铝颗粒直径为3.4 m时,尽管铝颗粒的直径较炸药颗粒直径小,但由于炸药颗粒的点火温度低,二者的点火时间相差不多。如果铝颗粒的直径为7.0 m,由于铝颗粒的点火滞后于炸药颗粒的点火,混合颗粒粉尘中可能形成双波阵面的爆轰波。     

Interaction of a shock wave with a loose dusty bulk layer

The interaction of a planar shock wave with a loose dusty bulk layer has been investigated both experimentally and numerically. Experiments were conducted in a shock tube. The incident shock wave velocity and particle diameters were measured with the use of pressure transducers and a Malvern particle sizer, respectively. The flow fields, induced by shock waves, of both gas and granular phase were visualized by means of shadowgraphs and pulsed X-ray radiography with trace particles added. In addition, a two-phase model for granular flow presented by Gidaspow is introduced and is extended to describe such a complex phenomenon. Based on the kinetic theory, such a two-phase model has the advantage of being able to clarify many physical concepts, like particulate viscosity, granular conductivity and solid pressure, and deduce the correlative constitutive equations of the solid phase. The AUSM scheme was employed for the numerical calculation. The flow field behind the shock wave was displayed numerically and agrees well with our corresponding experimental results.      

Turbulent Air-Flow Measurement with the Aid of 3-D Particle Tracking Velocimetry in a Curved Square Bend

A three-dimensional particle tracking velocimeter (3-D PTV) was applied to air-flow measurement in a strongly curved U-bend of a square cross-section. He-filled neutral-buoyant soap bubbles were employed as a flow tracer, and turbulent statistics including all Reynolds stress components were measured. The pressure-induced secondary flow, of which magnitude reached about 30% of the bulk mean velocity, was observed. The present experimental result is mostly in good agreement with the LDA data at higher bulk-mean Reynolds number taken by Chang et al. The effect of the secondary flow on the production mechanism of turbulent kinetic energy as well as on the distributions of the invariants of stress anisotropy tensor was examined in detail. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of particles on fluid turbulence in a turbulent boundary layer over a cylinder

The turbulent fluid and particle interaction in the turbulent boundary layer for cross flow over a cylinder has been experimentally studied. A phase-Doppler anemometer was used to measure the mean and fluctuating velocities of both phases. Two size ranges of particles (30μm–60μm and 80μm–150μm) at certain concentrations were used for considering the effects of particle sizes on the mean velocity profiles and on the turbulent intensity levels. The measurements clearly demonstrated that the larger particles damped fluid turbulence. For the smaller particles, this damping effect was less noticeable. The measurements further showed a delay in the separation point for two phase turbulent cross flow over a cylinder. The project supported by the National Natural Science Foundation of China     

Wavefront sensing for single view three-component three-dimensional flow velocimetry

We present the application of wavefront sensing to particle image velocimetry for three-component (3C), three-dimensional (3D) flow measurement from a single view. The technique is based upon measuring the wavefront scattered by a tracer particle and from that wavefront the 3D tracer location can be determined. Hence, from a temporally resolved sequence of 3D particle locations the velocity vector field is obtained. Two approaches to capture the data required to measure the wavefronts are described: multi-planar imaging using a distorted diffraction grating and an anamorphic technique. Both techniques are optically efficient, robust and compatible with coherent and incoherent scattering from flow tracers. The depth (range) resolution and repeatability have been quantified experimentally using a single mode fiber source representing a tracer particle. The anamorphic approach is shown to have the greatest measurement range and hence was selected for the first proof of principle experiments using this technique for 3D particle imaging velocimetry (PIV) on a sparsely seeded gas phase flow.     

二阶矩两相湍流模型中的改进算法

建立了融合SIMPLEC算法在内的考虑了浓度修正影响的颗粒压力修正方程。提出了二阶矩湍流模型下考虑浓度修正值影响的两相湍流流动的算法,并将它和没有考虑浓度修正值影响的二阶矩湍流模型进行了对照。结果表明在二阶矩模型中是否考虑浓度修正影响会不同程度地影响流场的速度以及浓度等参数分布,考虑浓度修正影响的二阶矩湍流模型更能有效地预测稠密两相湍流流动。