带钢镀后气雾冷却喷嘴雾化性能的试验研究

气雾冷却是一种适合于带钢镀后冷却的冷却方式。以空气和水为工作介质,对新开发的气水直交型喷嘴的雾化性能进行试验研究,主要测试流量密度分布、雾化角和流量压力特性。试验发现：喷嘴雾化后液滴粒度很小,且对水量变化不敏感;喷嘴的雾化角较小;喷气箱体的压力主要受喷水流量的影响,通过回归分析得到了用于喷箱设计的压力流量关联式。     

制备雾化锌粉技术研究

在以自行设计的限制式雾化喷嘴为核心的雾化装置上 ,研究了输液管的直径 ,喷嘴狭缝 ,喷射角在一定的条件下 ,雾化压力及熔融温度对液锌雾化效果的影响。结果表明 ,当雾化介质为N2 ,压力为 0 40～ 0 5 0MPa ,液锌温度为 6 5 0℃ ,液锌可以获得较理想的雾化效果。显微镜和电镜扫描观察发现制备的锌粉大部分为不规则状     

超声波重油喷嘴雾化特性的研究

介绍了一种新型流体动力式超声波重油雾化喷嘴。为了研究其雾化特性,以压缩空气和水为介质,利用激光粒度分析仪对超声波重油雾化喷嘴的雾化特性进行了详细的研究,分析了该型喷嘴的工作特点,研究了不同供气压力、供水压力和气液比(ALR)对喷嘴雾化性能的影响,同时也分析了粒径沿程变化情况。研究表明:流体动力式超声波重油雾化喷嘴雾化索太尔平均粒径非常小,为10～20μm,具有较好的应用前景。     

超声波雾化喷嘴的设计

在超声波雾化设计原理的基础上，将雾化喷嘴按照用途进行了分类，总结了三类超声渡雾化喷嘴。在研究雾化汽油等燃料类的喷嘴、雾化水类的喷嘴的基础上。着重叙述了制取微细金属粉末的超声波雾化喷嘴；在固体雾化技术研究的基础上。研制成一种新型的雾化喷嘴——双层固体技术雾化喷嘴，叙述了它的工作原理和雾化机理，并进行了简单的实验验证。     

雾化制粉用喷嘴的改进

针对雾化过程中易被中断的情况,通过对雾化过程中喷嘴中轴气流场压力分布的测量和分析,对喷嘴系统进行了改进,即将导液管装入喷嘴并延伸人喷嘴中轴气流场负压区。结果表明,雾化过程稳定,雾化制粉效率提高。     

WDH型气泡雾化喷嘴临界现象研究

文章对WDH型气泡雾化喷嘴出口的临界现象进行了理论与实验研究，这些研究结果不仅为设计气泡雾化喷嘴提供了可靠的数据库，还有助于进一步探索气泡雾化喷嘴的机理．     

WDH型气泡雾化喷嘴的流量特性研究

WDH型气泡雾化柴油、重油、渣油及奥里油燃烧器已在各行业的工业炉窑上得到了广泛的应用。本文对WDH型气泡雾化喷嘴的流量特性进行了实验研究，此项研究结果对进一步开发WDH型气泡雾化喷嘴的应用领域将发挥重要的作用。     

宝钢二炼钢LT系统喷嘴雾化特性实验研究

对宝钢二炼钢LT系统蒸发冷却器所用的气雾两相流喷嘴的雾化特性进行了实验研究和分析。实验包括流量压力特性、雾化角、颗粒度的测试等。测试结果表明该喷嘴雾化效果较好，液滴SMD在11—69μm范围内，喷嘴的气体参数与水状态参数彼此无影响。研究结果为优化喷嘴布置提供了依据。     

敞开式水雾化喷嘴

水雾化喷嘴是水雾化法生产金属粉末的关键设备。对于常规喷嘴,增大雾化夹角及提高雾化压力均可提高金属粉末的细粉率,但也都会遇到堵嘴问题,从而导致雾化过程中断。本研究分析了雾化过程中的堵嘴机理,设计了一种新型敞开式水雾化喷嘴,对其进行强度计算,并进行雾化试验。结果表明,此新型敞开式雾化喷嘴可以有效避免水雾化金属粉末过程中气囊的形成,可从根本上解决以往生产中经常出现的堵嘴问题。而对单个敞开式喷嘴而言,提高雾化夹角,增加孔数,以及提高雾化压力,均可以显著提高细粉率。     

双层气雾化喷嘴结构突出高度的数值分析

采用计算流体软件Fluent,通过对双层气雾化喷嘴气流场、颗粒粒径以及温度场的数值模拟,分析导液管突出高度对气流场、颗粒粒径以及温度场的影响。结果表明,导液管突出高度为6mm时气流场结构最优,雾化所得粒径最小。总结气雾化过程中液滴在特殊气流场中破碎的主要过程,为双层气雾化喷嘴结构设计及机理研究提供一定的借鉴意义。     

Water atomisation of metal powders: effect of water spray configuration

ABSTRACT

We consider the effect of water spray configuration on the fineness and uniformity of a metal powder produced by water atomization of a melt stream. The effects of water spray travel distance, nozzle design, water pressure, melt superheat, and apex angle on the particle size distribution of a metal powder is studied via a laboratory-scale water atomizer; the main focus is on the first two, which are usually fixed parameters of the atomizer. Correlations are proposed relating the mass median size and standard deviation of the powder to the parameters cited. Similar correlations for water pressure, melt superheat, and apex angle have been reported elsewhere; we present data on these effects to confirm the validity of our results, especially as Bi-42%Sn powder has not been studied before. What is new are results on the effect of water spray travel distance and nozzle design on the mass median size and standard deviation of powder.     

Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

A three-dimensional model of the spray forming method

A three-dimensional model has been formulated to calculate the shape of the general preform, using vector calculus. The shape of a rod, tube, plate, or irregular preform can be calculated at given spray forming conditions. The shape of a spray-formed rod was analyzed at various spray forming conditions using the three-dimensional model. The effects of spray forming parameters, such as spray distribution parameters, angular velocity of rotation, withdrawal velocity, spray angle, and eccentric distance on rod shape, were analyzed. The most important parameters affecting the shape of rods are the spray distribution parameters and the withdrawal velocity. The dynamic evolution of rod shape with a stepwise variation of the withdrawal velocity during spray forming was investigated. The effect of a stepwise change of the withdrawal velocity was the same as that of the scanning atomizer. The calculated surface profiles were compared with those of spray-formed 7075 aluminum alloy rods prepared on a pilot scale. The calculated results for the surface profiles were in agreement with those of the spray-formed rods.     

Spray Deposition Behavior and Numerical Simulation of Growth of Tubular Preform in Spray Forming Process

 Analysis on the deposition behavior of spray on deposition surface was made and an optimization method for the movement parameters (u, ω) of substrate was obtained. Simultaneously, a mathematical model of growth of tubular preform, specifically aimed at the kind of atomizer that is fixed and with a tilt angle was established. By integrating the optimization method and the mathematical model, the growth process and shape of preform were simulated. The results show that the tilt angle of atomizer plays an important role on the dimensions and shapes of tubular preforms and it can provide a guidance for the development of spray forming equipment.     

Modeling of spray deposition: Measurements of particle size,gas velocity,particle velocity,and spray temperature in Gas-Atomized sprays

Spray deposition is a novel manufacturing process which is currently being developed for producing near-net-shape preforms. Spray deposition involves the creation of a spray of droplets by a gas atomizer and the consolidation of these droplets on a substrate to create a preform. In order to maximize the metallurgical benefits of spray deposition, a thorough characterization of momentum and heat transfer in the gas-atomized spray is required. The present paper describes measurements of particle size, gas velocity, particle velocity, and spray temperature in gasatomized Sn-Pb sprays. Measurements were performed on steady-state axisymmetric sprays which were generated using a close-coupled gas atomizer with Sn-5 wt p t Pb and Sn-38 wt p t Pb alloys, atomizer gas flow rates of 2.5 g/s (0.56 MPa) and 3.4 g/s (1.04 MPa), melt flow rates of 35 and 61 g/s, and atomizer-substrate distances of 180 and 360 mm. Gas velocities in the range to 4 m/s were measured using Pitot tube and laser Doppler anemometry (LDA). Droplet velocities in the range 3 to 32 m/s were determined from photographic streak-length measurements and LDA. Oil calorimetry of the spray enthalpy indicated that the spray temperature decreased with increasing axial distance from the gas atomizer, increasing gas flow rate, and decreasing melt flow rate. Formerly Doctoral Student, Department of Metallurgy and Science of Materials, Oxford University     

喷射沉积铝合金管坯工业化生产中的控制系统研究

对多层喷射沉积制备大规格管坯工业化生产特点进行了分析，表明Osprey多程技术更适宜于喷射沉积工业化生产。构建了由系统管理层／控制层／设备层组成的三层递阶控制结构。对关键工艺参数的闭环控制技术进行了研究，提出了漏包连续移液和基于积分分离PID的液位精确控制结构和方法，研究了管坯沉积层厚度的在线检测及喷嘴喷射高度在线反馈控制方法，提出了基于沉积室微正压环境的氧含量控制技术。控制系统及相关控制技术已在国内首条自行研制的喷射沉积制备铝合金管坯工业化生产设备中得到应用，已生产出最大长度1500mm、最大壁厚300mm、不同内径的铝合金产品。     

电弧喷号机故障影响因素分析及其改进措施

钢坯标识质量稳定对于保证铸坯生产顺行及质量管理具有重大意义。分析了武钢中厚板厂二切生产线上影响喷号机运行不稳定的各种因素,包括喷嘴的对称度、压板压丝的角度、压送丝轮的压力、金属丝盘的缠丝质量等。提出了相应的改进措施并进行实施,取得了喷号机喷号清晰、运行稳定的效果。     

The selection of the spray deposition rate during the spray rolling process

This article presents a detailed theoretical analysis of the selection of the maximum and minimum spray deposition rates under steady-state conditions during the spray-rolling process. The following predictions are made on the basis of the preceding theoretical analysis. First, the key factor that may control the minimum spray deposition rate is either the removal of porosity or the removal of prior droplet boundaries. With an increase in initial liquid fraction at the deposit/roll interfaces, the mechanism changes from the former to the latter. Second, the mechanism that controls the maximum spray deposition rate is related to either the drag-in angle or the distance between the nozzle and the deposited material’s surface. With an increase in roll diameter or a decrease in distance between the nozzle and the roll-axis plane, the controlling mechanism is changed from the former to the latter. Third, both the calculated maximum and minimum spray deposition rates markedly increase with an increase in roll diameter and roll rotational frequency. In addition, the present theoretical analysis suggests that spray rolling can be optimized to manufacture strips with a high production rate.     

雾化器往复扫描喷射共沉积过程的数值模拟

喷射沉积过程是一个多参数共同影响的复杂过程。通过对雾化器往复扫描规律以及其它工艺参数的研究，可以对喷射沉积过程进行工艺优化。基于对沉积过程的分析，建立了雾化器往复扫描喷射沉积的数值模型。采用计算机数值模拟技术与实验结合的方法，着重研究了喷射成型过程中雾化器的扫描运动对成型的影响；实验证明，根据分析所得到的雾化器扫描曲线，可以准确预测这类成型产品的形状和尺寸。     

An experimental study on the atomization characteristics of the nozzle for the after-pot cooling of galvanized steel sheets

Air-atomized fog cooling is particularly suitable for the after-pot cooling of galvanized steel strips.With air and water serving as working media,an experimental study was conducted on the atomization characteristics of a newly-developed cross-flow type of fog nozzles.The water flux distribution,spray angle and pressure of water and air were measured.The results show that the water droplet size was small and insensitive to the water flow rate.The spray angle was small and the water flow rate slightly affected the air pressure in the chamber.An empirical correlation between the pressure in the chamber and the gas flow rate was obtained for the purpose of equipment design.