激光衍射仪在雾化油滴粒度测量上的应用

本文简述了应用以Fraunhoffer几何光学理论为基础的LPI—2型激光衍射粒径仪测量雾化油滴尺寸和分布特性,阐明了这一应用对深入开展油雾化研究的重要意义。     

火花点火发动机激光诱导荧光及散射测量技术应用研究

本文就汽车发动机的激光测量技术问题，重点介绍了散射光法及激光诱导荧光法在发动机研究开发过程中的应用及其机理。这些方法对电子控制稀燃火花点火发动机的设计和优化具有重要意义。     

便携式超声波流量计在供水流量测量中的应用及注意事项

介绍了便携式超声波流量计在制药行业的应用，使用方法及注意事项。     

长测距三维激光扫描仪在露天矿山测量中的应用

利用长距离三维激光扫描仪进行露天矿山测量可以实现不可估量的测量成效.通过分析长距离三维激光扫描仪在露天矿山测量原理,以某矿山工程为例,利用三维激光扫描仪对矿山测量中的数据采集、处理、对比进行系统化分析,总结了三维激光扫描仪开展露天测量的优势及注意事项.     

激光散射理论在汽轮机蒸汽湿度及水滴直径测量中的应用

蒸汽湿度的存在不但降低汽轮机组的运行效率,而且会引起严重的叶片水蚀,给汽轮机组的经济性和安全性带来很大的危害.根据激光散射理论和Mie散射理论,利用半导体激光器发射出三个不同波长的光能够在线测出汽轮机末级蒸汽湿度及水滴颗粒大小和分布,为监控和减少湿蒸汽对汽轮机的危害提供最直接的数据.图5表1参11     

激光数码全息技术在两相流三维空间速度测量中的应用

研究了利用激光数码全息技术实现两相流三维空间速度场测量的方法.用1台脉冲激光器照射两相流,平面光和颗粒衍射光发生干涉,在数码相机的CCD平面上生成全息图像.用1台跨帧数码像机连续拍摄两相流全息图像,对全息图应用基于小波变换的三维图像重建算法,在计算机上实现物体三维图像的重建,再利用图像互相关测速技术从连续的重建三维图像中提取两相流三维空间的速度场.实验中将2只置于不同空间位置的喷嘴向不同方向喷射雾化的气液两相流,并对生成的流场进行测量.结果表明该方法可以实现两相流三维空间速度场测量.     

激光诱导磷光测温技术在缸内温度测量中的应用

将激光诱导磷光测温技术应用到发动机缸内气体的二维温度测量中.其原理是利用Dy:YAG磷光剂受355 nm波长的激光激发后辐射的458 nm和494 nm磷光强度比进行温度测量,实验在一台侧向换气的光学发动机上进行,测试了该发动机压缩行程的二维温度分布,与由缸压计算的缸内平均温度比较,误差均小于5%.     

激光精密测量技术在大型水轮发电机组安装中的应用

为提高大型水轮发电机组安装的测量精度和效率,提出了AT901-LR激光跟踪仪测量方法,即利用Leica公司生产的AT901-LR跟踪仪配合T-Probe、球棱镜、基座及专用工装,采用统一的三维控制网的点位布设,通过对水轮机部件、发电机定子组装过程测量的实际应用,并与测圆架测量结果进行比较。结果表明,测量结果偏差极小,精度高,符合现场安装要求,从而验证了AT901-LR激光跟踪仪测量方法具有较高的精度,这也为大型水电机组安装提供了一种新型的测量工具和测量方法。     

磁记忆等检测技术在锅炉压力容器焊接残余应力测量中的应用简析

针对目前焊接残余应力常用的几种无损测量方法进行了简单介绍和比较。提出了一种新的无损测量方法——金属磁记忆检到技术。分析了该技术在锅铲压力客器焊缝中的应用前景及存在的问题。     

激光技术在修复机车柴油机曲轴中的应用

1概述激光在铁路上的应用起步较晚,尤其在修复机车零件中的应用较少。在修理机车零部件的过程中,大多采用传统的焊接方法或电刷镀。     

Measurement of droplet size distribution in core region of high-speed spray by micro-probe L2F

In order to investigate the distribution of droplet sizes in the core region of diesel fuel spray, instantaneous measurement of droplet sizes was conducted by an advanced laser 2-focus velocimeter （L2F）. The micro-scale probe of the L2F is made up of two foci and the distance between them is 36 lain. The tested nozzle had a 0.2 mm diameter single-hole. The measurements of injection pressure, needle lift, and crank angle were synchronized with the measurement by the L2F at the position 10 mm downstream from the nozzle exit. It is clearly shown that the droplet near the spray axis is larger than that in the off-axis region under the needle full lift condition and that the spatial distribution of droplet sizes varies temporally. It is found that the probability density distribution of droplet sizes in the spray core region can be fitted m the Nukiyama-Tanasawa distribution in most injection periods.     

Advances and challenges in droplet and spray combustion. I. Toward a unified theory of droplet aerothermochemistry

Major theoretical accomplishments in droplets and sprays in the twentieth century are reviewed in this two-part article, with emphasis focused upon the evolution of scientific concepts, paradigms and methodologies. A structural spray theory, which was developed from an early view of isolated droplets, has evolved in to a new view that the interacting droplet and meso-scale structures and clusters of many-droplet systems are also fundamental entities in practical sprays. The first part of this work addresses the major concepts in analytical developments, which serve as the framework of modern theories of an isolated and interacting droplet. Outstanding issues and critical bottlenecks that have prevented further advancement of the existing analytical theory of droplet physics are examined, and an emerging research trend in a unified theory of droplet phenomena discussed. Recent accomplishments and future prospects of a unified theory are presented to complement the status of this special branch of droplet science and its future application.     

Temperature distribution on inclined plate caused by interaction with supersonic jet

IntroductionThe phenomena of the impingement of a supersonicjet on a solid obstacle is very interesting and importantin relation to the aeronautical and other industrialengineerings[']-l']. A large number of papers hadconcerned with the impingement on a perpendicularplate and evidenced the flow phenomena and thepressure distribuhon on a plate and so on. However, theinvestigation of the impingement on an inclined platecan only be found in merely several papers['-']. Ih thesestudies, it is menti…     

A spherical cell model for multi‐component droplet combustion in a dilute spray

A model for sphericosymmetric thin‐flame combustion of a multi‐component fuel droplet in a dilute spray has been developed using a unit cell approach. The gas‐phase transport has been modelled as convective–diffusive while the liquid‐phase processes as transient–diffusive. Convective heat and mass transfer condition has been used at the cell surface. The results indicate that evaporation and combustion characteristics of the droplet are strongly affected by the variation of both ambient conditions and convective transfer coefficients. Using the model, the effects of droplet spacing in spray, ambient oxidizer concentration, ambient temperature and pressure have been considered. Droplet life increases with decrease in droplet spacing, ambient temperature and ambient oxidizer concentration. However, droplet life has a weak dependence on ambient pressure. Copyright © 2001 John Wiley & Sons, Ltd.     

The effect of ambient pressure on the evaporation of a single droplet and a spray

The effect of ambient pressure on the evaporation of a droplet and a spray of n-heptane was investigated using a model for evaporation at high pressure. This model considered phase equilibrium using the fugacities of the liquid and gas phases for the behavior of a gas being real, and its importance in the calculation of the evaporation of a droplet or spray at high pressures was demonstrated. For the evaporation of a single droplet, the fact that the droplet's lifetime increased with pressure at a low ambient temperature, but decreased at high temperatures, was explained with pressure and the droplet's temperature determining phase equilibrium. In this study, it was also found that the evaporation of a spray can be explained in terms of multiplex dependencies of the atomization and evaporation of a single droplet. The evaporation of a spray was enhanced by increasing the ambient pressure and this effect was more dominant at higher ambient temperatures.     

Effects of fuel droplet size on soot formation in spray flames formed in a laminar counterflow

The effects of fuel droplet size on soot formation in spray flames formed in a laminar counterflow are investigated experimentally and numerically. Sauter mean diameter (SMD) of quasi-monodispersed fuel spray (n-decane) is carefully controlled independently from the other spray characteristics using a frequency-tunable vibratory orifice atomizer, and the two-dimensional spatial distributions of soot volume fraction and soot particle size are measured by laser induced incandescence (LII) and time resolved LII (TIRE-LII), respectively. In addition, the soot formation processes are examined in detail by a two-dimensional direct numerical simulation (DNS) employing a kinetically based soot model with flamelet model. The results show that the soot formation area and location are strongly affected by the SMD of the fuel spray. As the SMD of the fuel spray increases, the average soot formation area expands, whereas local suppression of soot formation is instantaneously observed in the spray flames because of the appearance of groups of unburned droplets. The size of soot particles tend to be larger in the outer part of the soot formation area compared to soot in the inner part. This is because the surface growth of soot particles markedly proceeds compared to the coagulation and oxidation.     

Experimental and Numerical Evaluation of the Performance of Supersonic Two-Stage High-Velocity Oxy-Fuel Thermal Spray （Warm Spray） Gun

The water-cooled supersonic two-stage high-velocity oxy-fuel (HVOF) thermal spray gun was developed to make a coating of temperature-sensitive material,such as titanium,on a substrate.The gun has a combustion chamber (CC) followed by a mixing chamber (MC),in which the combustion gas is mixed with the nitrogen gas at room temperature.The mixed gas is accelerated to supersonic speed through a converging-diverging (C-D) nozzle followed by a straight passage called the barrel.This paper proposes an experimental procedure to estimate the cooling rate of CC,MC and barrel separately.Then,the mathematical model is presented to predict the pressure and temperature in the MC for the specific mass flow rates of fuel,oxygen and nitrogen by assuming chemical equilibrium with water-cooling in the CC and MC,and frozen flow with constant specific heat from stagnant condition to the throat in the CC and MC.Finally,the present mathematical model was validated by comparing the calculated and measured stagnant pressures of the CC of the two-stage HVOF gun.     

Structure and temperature distribution of a stagnation-point Diesel spray premixed flame

We experimentally examine the flow and flame characteristics of a stagnation point premixed flame influenced by Diesel sprays. In the experiment, distributions of drop size, drop axial velocity and its fluctuation as well as the gas phase temperature are measured by using the phase-doppler particle analyzer and a thin thermocouple. As might be expected, similar to the gasoline spray flame, the partially prevaporized Diesel spray flame is composed of a weak blue flame zone, indicating the burning of methane fuel, and a strongly luminous zone containing many bright yellow lines showing the passages of burning Diesel drops. It is found that the axial temperature profiles at various radial positions consist of an upstream preheat region, a maximum temperature downstream of the blue flame and a downstream region with a declined temperature curve because of the heat loss to the quartz plate. The SMD of the drops increases from the upstream preheat region to a maximum near the blue flame and then decreases in the downstream burning zone. Along the axial position, the drops are decelerated in front of the flame but accelerated when passing through the blue flame. It is also interesting to note that the radial distributions of SMD and number density of drops in the upstream region are mainly influenced by small drops flowing outward, since the upstream vaporization of Diesel drops is very limited; while those in the downstream region should be influenced by both small drops flowing outward and Diesel drops burning. From the experimental observations, there are impinging and bouncing of Diesel drops downstream of the spray flame near the quartz plate, resulting in a small amount of soot and carbon deposits on the wall. These interesting phenomena will be reported in the near future.     

Analysis of flame gas velocity and temperature distribution from double-pipe nozzle jet in a production unit for spherical particles by flame spray method

The flame spray method for preparing spherical powders is a technique in which solid particles are forced to fuse into spheres by exposing them directly to the combustion flame, and has already been applied to producing ceramic (metal) spherical powders. With this technique, it is critical to analyze quantitatively the fusing and sphering characteristics of solid particles, and thus the distributions of gas velocity and temperature of the flame gas have to be calculated first. However, little research has been conducted regarding this subject. In this study, a combustion model is formulated to calculate the profiles of gas velocity and temperature for the fuel gas flame jetted from the commonly used coaxial double-pipe nozzle. The calculation agrees roughly with the flame shape observed in experiments, implying the possibility of using this model to calculate the heat transfer from flame gas to solid powders. © 1997 Scripta Technica, Inc. Heat Trans Jpn Res 25(4): 201–213, 1996     

Spatial distribution of light absorption in organic photovoltaic devices

In this paper we present methods for the optimization of light absorption of organic photoelectric bilayer devices like organic photodetectors and organic solar cells, which show the best performance if it is ensured that the spatial density of the absorbed light energy reaches its maximum in certain “active” areas. Mathematical simulations show interesting spatial distributions of light absorption depending on the thicknesses and the optical constants of the individual device layers. Our methods permit to dispose the maxima of absorption density to the area near the interface between the active layers of the bilayer device. We built photovoltaic devices according to the simulated configurations and gained improvements of the power conversion efficiencies of more than one magnitude. Parametric studies were carried out, which give us a suggestion for the potential active materials. Furthermore we analyzed the correlation between the photocurrent and the absorption density in given areas around the p–n junction, which will lead to better understanding of the diffusion range of dissociated charge carriers.