CFD在热轧带钢层流控冷系统中的应用

利用CFD数值仿真技术模拟了层流水冷系统中层流冷却装置复杂的内部流场以及冷却水自由下落后的外部流场,并通过对仿真流场的分析,优化设计了冷却装置内部结构,精确地确定了控制冷却数学模型中强迫对流宽度值,为提高控冷系统的控制精度奠定了基础.     

有积水的钢板的冷却特性

在实验室利用移动的热钢板,研究了钢板上积有用水管喷头喷淋的冷却水的冷却特性。发现用水管喷头喷淋的冷却能力是随积水的多少而变化的,当积水的深度约50毫米时冷却能力最大。将喷头升高,有积水的冷却能力稍有增加,而无积水的冷却能力下降。本文研究了流水形状,钢板温度这些情况对有积水的冷却能力的影响。并将水管喷头水流的冷却能力与大间距的狭缝喷头水流的冷却能力作了比较,发现在高的水流强度下,狭缝喷头水流的冷却效果比水管喷头水流的冷却效果差;在低的水流强度下,两种水流的冷却效果差异不大。     

纯水冷却装置散热器片的清洗方法

本介绍了纯水冷却装置散热器片易堵塞，使付水流动不畅，影响了对纯水的冷却效果。通过实践采用一种反冲洗原理，即节约了工时，降低工人们的劳动强度，又避免了对设备造成的危害。     

超快冷设备中清除钢板表面残留冷却水的方法

对于某些特殊钢板,轧后冷却强度小,表面质量要求高,需要用空气吹走钢板表面残余的冷却水的工艺要求,设计了一种既能喷射气体,又能喷射水的装置,可通过喷射气体进行吹扫,以喷射水流对钢板继续冷却,节约了超快冷装置中布置吹扫装置的空间,有效地清除了表面的残留冷却水,使钢板性能得到了提高。     

带钢热轧机数字模型的温度特性

热带轧机输出辊道上带钢加速冷却的模型已经开发出来，模拟冷却考虑一块热轧带钢．冷却过程遵从传递机理——传导、对流和辐射．使用水帘和水流喷嘴产生对流换热。在通常的文献中，对这些水冷却装置的每一种都明确了冲击和稳定的沸腾区。为了计算对流热传导系数，冲击区和稳定的     

磁控溅射镀膜中钛靶冷却系统的仿真与优化

在磁控溅射镀膜过程中,纯钛靶材会在辉光放电中受到离子轰击而迅速升温,可能会导致靶材或永磁体等关键部件毁坏,为保证钛靶的正常工作温度以及溅射过程的稳定性,需要通过水冷等方式来降温。为了研究水冷过程中不同冷却结构对钛靶换热效率的影响,从增大换热面积和增加水流的湍流效果出发设计冷却通道结构,通过改变水流入口速度以及进出口的方向来获得最优的冷却系统结构。结果表明:平面冷却通道的换热效果优于蛇形冷却通道,且钛靶表面凸起结构能有效增加水流湍流效果;对于任意冷却结构来说,随着入口水流速度的增加,钛靶表面最高温度明显降低;水流进出口沿着冷却内腔切向方向且呈相对平行时,冷却系统的换热效果最优,钛靶表面温度分布也更为均匀。     

铜冷却壁水流通道特性分析

通过对铜冷却壁热模拟试验结果进行传热分析，提出了优化铜冷却壁水流通道断面设计的方法。优化后的水流通道可以在提高铜冷却壁冷却能力的基础上，达到减少铜冷却壁铜料消耗和节约冷却水用量的双重目的。     

350轧机工艺线上轧材快冷设备的掌握

在350轧机机组中于变形的各个阶段安装了控制轧材温度的设备。规定小型材生产线上在恒温炉内煤气加热的中间坯，以及变形后的钢材，都在连续水流装置中快速冷却；而中型材是变形后快速冷却的钢材。所述水冷设备可以有效地控制钢的组织形成过程和轧材的机械性能水平。     

层流冷却装置冷却能力的确定

以某试验轧机的控制冷却设备为研究对象,通过控制阀门的开口度绘制开口度-流量曲线,通过采取增加反馈控制、保证水箱的水位稳定和气源稳定、集管单向打开等措施,提高阀门开口度稳定性。分析认为,在集管开口度30%~80%范围内,开口度-流量曲线成线性变化,冷却装置的最大水流密度在1 200 L/(m~2·min)以上,可以满足不同冷却速度的要求。     

钢管冷却喷淋水量对换热系数的影响

 采用一种钢管外喷淋装置,通过在钢管中预埋热电偶测量钢管冷却期间的温降曲线,研究了喷淋水量对钢管冷却强度的影响。利用有限元模拟软件对测量结果进行分析,建立了钢管表面对流换热系数和水流密度的数学关系模型,将模型嵌入了钢管温度场计算软件当中,软件的计算精度进行了工程验证。结果表明,融合了该换热数学模型的钢管温度场模拟软件计算精度达到90％以上。     

Heat Transfer during Multiple Jet Impingement on the Top Surface of Hot Rolled Steel Strip

Using a unique pilot facility a series of tests were conducted using three top jets to simulate the heat transfer that occurs during run‐out table (ROT) cooling. Steel samples instrumented with internal thermocouples were tested on this facility and the effect of top jet configuration (nozzle spacing of 40 to 115mm), and water flow rate (15 and 30 1/min) were quantified using moving plate samples. The multiple top jet work indicated that heat transfer across the plate width varies significantly and is high directly under the nozzle but decreases rapidly away from the nozzle in the interaction region. As cooling progresses a much larger wetted region occurs and more uniform cooling is experienced across the plate. Multiple jet cooling experiments have also confirmed that nozzle spacing does have an effect on heat transfer. This effect is predominate in the interaction region where closer nozzle spacing leads to enhanced and more uniform heat transfer in the lateral direction across the plate width away from the nozzle. As expected higher water flow rates led to higher heat transfer both under the nozzle and in the interaction region.     

超薄规格钢板淬火的板型控制研究

在超薄规格钢板的淬火过程中,根据淬火后钢板板型的总体变化规律,研究了其淬火板型的控制机理和控制技术。结果表明,对于超薄规格钢板,淬火机设备在安装或校准的过程中,不仅要确保喷嘴精度,即钢板上下面冷却速度相同,而且要保证下喷嘴喷射角度有一定的负偏差,即喷嘴的喷水交叉线和钢板的上下面中心线三线重合,才能实现钢板上下面同步相变。该板型控制机理成功应用于淬火机设备的调整和校正,配以合理的淬火工艺参数,超薄规格钢板淬火后的板型不平度稳定在可控范围内。     

钢板自动测宽系统的开发与应用

为提高宽度测量精度,济钢中厚板厂2500产线在粗轧机前安装在线自动测宽系统,该系统主要由CCD器件、视频自动增益控制器、图像采集卡、工控计算机等组成。系统应用后,可实时测量轧制过程中钢板宽度,便于随时调整压下量,提高了长宽定尺板合格率,成品切边放尺量减少了4 mm,产品改判率降低0.02%。     

Flow separation and liquid rundown in a gas-atomization process

“Rundown≓ filming mode was studied in a confined design gas-atomization nozzle of converging/ diverging construction. In this mode, liquid metal runs down to a certain distance up to ≈3 mm on the outer surface of the metal delivery tube in the form of a thin film. Atomization then takes place through the disintegration of this film by the oncoming gas. The rundown effect was simulated by water, and the supersonic gas flow outside the nozzle was visualized by Schlieren photography. It was found that rundown is caused by the liquid being drawn into a separated flow region on the wall of the delivery tube. This separation comes about as a result of the action on the boundary layer of adverse pressure gradients associated with the shock waves in the gas flow. Geometric conditions required for observing rundown are discussed, and a method is outlined for assessing whether a given nozzle design is likely to produce the effect. Evidence is also presented for the filming of the liquid on the tip of the nozzle by radial spreading.     

连铸板坯结晶器调宽装置的故障与改进

针对大断面板坯结晶器调宽机构使用中频繁出现的故障，通过深入分析找出了原因，并提出了改进方案，使用证明改进后的调宽机构工作稳定性能良好。     

Comparison of Fixed and Rotating Spray Plate Sprinklers

A comparative study of two types of spray sprinklers was performed. Rotating spray plate sprinklers (RSPSs) and fixed spray plate sprinklers (FSPSs) were evaluated individually in open field conditions. The water distribution, wind drift, and evaporation losses during the evaluations were measured under low, medium, and high wind speed conditions with three nozzle diameters and two nozzle heights above the soil surface. Individual spray sprinkler water distributions were mathematically overlapped to simulate the water distribution resulting from sprinkler machines. The water distribution of the RSPS had a conical shape, whereas the FSPS concentrated the water application in a circular crown. The uniformity coefficient of the simulated water application in sprinkler machines fitted with RSPSs or FSPSs was >93% in all cases. However, the RSPS could attain a higher uniformity coefficient at higher spacing along the lateral. For the nozzle diameters of 6.7 and 7.9 mm, the wetted width produced by the RSPS was larger than that of the FSPS. Also, the peak instantaneous precipitation rate of the RSPS was smaller than that of the FSPS.     

Mathematical Modeling of VOD Oxygen Nozzle Jets

This study has focused on numerically exploring the oxygen flow in the convergent‐divergent De Laval nozzle. The De Laval nozzle has been commonly used as oxygen outlet at the lance tip in the vacuum oxygen decarburization (VOD) process. The nozzle geometry used in an active VOD plant was investigated by isentropic nozzle theory as well as by numerical modeling. Since an optimal nozzle design is only valid for a certain ambient pressure, one VOD nozzle will be less efficient for a large part of the pressure cycle. Different ambient pressures were used in the calculations that were based on the De Laval nozzle theory. Flow patterns of the oxygen jet under different ambient pressures were studied and the flow information at different positions from the nozzle was analyzed. In addition, the study compared the effects of different ambient temperatures on jet velocity and dynamic pressure. The predictions revealed that the modeling results obtained with the CFD modeling showed incorrect flow expansion, which agreed well with the results from the De Laval theory. Moreover, a little under‐expansion is somewhat helpful to improve the dynamic pressure. The jet dynamic pressure and its width for the specific nozzle geometry have also been studied. It has been observed that an altering ambient pressure can influence the jet momentum and its width. In addition, a high ambient temperature has a positive effect on the improvement of the jet dynamic pressure.     

高压水雾化生产低含氧量金属粉末装置及其工艺特征

所研制的高压水雾化生产低含氧量金属粉末装置属于整体密封型。由喷嘴与雾化管或与雾化小室等组成雾化器,水压达16MPa。使用射吸式水力旋流器,使雾化制粉和粉末收集同时进行。其工艺特征主要是制粉过程与空气避免接触。雾化后的热态粉末,尽快落入冷水并作剧烈搅拌,使粉末表面不产生氧化薄膜,从而生产出低含氧量全属粉末。装置结构紧凑,造价低,操作维护方便,除供生产使用外,也可供实验室使用。文中扼要阐述了本装置的工作原理、主要性能、工艺特征以及装置中几个需要解决的技术问题。     

2300中板四辊轧机的辊型研制

根据2300中板轧机的设备特点、轧制产品的工艺状况,开发了一个能适应轧件宽度变化范围较大的2300四辊轧机支撑辊辊型的计算机仿真程序,并研制了一种新的2300四辊轧机支撑辊辊型曲线,以提高该轧机的板形控制能力。研制的新支撑辊辊型曲线经过一年的工业化生产,取得明显的实效,钢板的横向同板差下降幅度达60%~75%;同时钢板的板形明显改善、薄板的边浪现象基本消除;另外轧制压力下降幅度达5%~7.5%,辊间压力分布变化趋缓、轧辊磨损减少、使用周期延长。     

马钢热轧板厂CSP结晶器在线调宽控制技术

马钢CSP薄板坯连轧生产线上的连铸机使用漏斗型板式结晶器．其宽度和锥度可在连续浇注过程中不降低拉坯速度的前提下在线连续调节。重点介绍了结晶器在线调宽的原理、方法以及控制系统的组成、结构与功能。