中厚板淬火及控冷过程流量调控装置供水方式研究

利用计算流体动力学(CFD)和有限元数值模拟方法(FEM),对中厚板淬火及控冷过程流量调控装置供水方式进行了研究。对流量调控装置关键件—低位水箱进水方式、低位水箱形状、进水管有无阻尼孔等结构出水均匀性进行比较,得出方形水箱、水箱多路进水及进水管有阻尼孔情况下出水效果最理想的结论。     

基于数值模拟的电炉氧枪结构及参数优化

探索基于数值模拟对电炉氧枪结构及参数进行优化.在氧枪常用工作压力等条件下,应用数值模拟软件对氧枪射流特征进行了模拟,得到了不同氧枪结构及参数下的射流特性.经比较,主氧压力0.79MPa情况下当弧形燃烧室长度为80mm,环氧流量为450m3/h时,氧枪超音速核心段长度最长,氧枪聚合度最好,射流特性最优.并进行了冷热态实验,实验结果与数值模拟结果基本相符,证明了数值模拟结果的可信性.     

中厚板控制冷却系统流量调节特性分析

中厚板控制冷却水流量的控制精度直接影响钢板冷却过程的控制精度.以应用于多家中厚板厂的一种典型控制冷却设备为例,分析其系统流量调节特性,从电动调节阀、手动蝶阀、高位水箱等几个方面分析不同冷却单元之间流量控制存在偏差的原因,给出提高流量控制精度的有效方法,为控制冷却设备的优化设计提供参考依据.     

φ13mm高碳线材控冷工艺实践

介绍了大直径高碳钢线材控冷机理，并对冷却风机，辊道速度，水箱等控冷参数设计做了较为详细的论述。     

层流冷却系统流量标定与板形控制

讨论中厚板冷却系统流量标定问题,开发一种新型流量控制技术,通过标定调节阀在不同开口度下集管流量值,利用三次方方程回归出流量-调节阀开口度设定曲线;生产中根据流量开口度曲线进行水比的调整,提高冷却系统流量控制精度以及控冷后板形。     

热轧板材在线控冷装置集管水流均匀性的研究

对某钢厂热轧板材轧后控冷水箱的阻尼板布置形式进行数值模拟分析和研究。通过分析各种阻尼布置形式的速度流场,确定更有利于集管形成均匀水流的阻尼板布置形式,提高控冷效果。     

圆形冲击射流破断现象的实验和数值模拟研究

钢板轧后控冷ACC装备的管状射流可能会出现破断现象,这对生产是很不利的。通过实验和数值模拟的方法,研究了破断长度与射流直径、射流速度和射流流量的关系,并给出了射流破断长度与射流出口韦伯数We的拟合曲线关联式。     

中厚板冷却集管供水装置关键参数的研究

层流冷却过程中钢板均匀性控制是影响中厚板轧后冷却系统的重要因素。供水系统合理性设计是层流冷却系统实现钢板各向冷却均匀性的保障。对于层流冷却设备供水装置而言,不仅仅要提供足够的冷却水量确保层流冷却系统的冷却能力,而且要确保集管冷却水源的稳定性。针对集管供水装置建立了高位水箱到分流水箱水力学模型,通过迭代方法计算能够保障供水系统稳定性的最优输水管道的管径和高位水箱临界水位高度。     

多排密集圆孔气体冲击射流换热的实验研究

气体冲击射流的换热系数是设计喷气冷却装置必需的参数。本文采用实验方法研究了多排密集圆孔气体冲击射流的换热过程,主要考察了射流雷诺数ReD,普朗特数Pr,无量纲喷嘴间距Xn/d,无量纲喷射高度H/d和排气方式对平均对流换热系数的影响。实验结果表明:平均努谢尔数NuD随ReD数的0.69次幂增长,随无量纲数Xn/d的-0.269次幂和无量纲数H/d的-0.273次幂的方式减小,同时设置排气通道会显著提高换热系数。实验数据整理成平均努谢尔数NuD与ReD数、Pr数、无量纲间距Xn/d、无量纲喷射高度H/d的准则关系式,测量值与回归结果偏差在7%的范围内。得到的准则关系式与Martin公式比较,更适合于高开孔率的密集冲击射流。     

储热水箱分层特性的研究

储热水箱被广泛使用在太阳能集热系统以及家用电加热热水器中,是决定集热系统和热水器性能的关键因素之一,储热水箱分层效果的好坏决定了集热系统的效率及热水器的热水出水量.绘制了直接进口和三层孔板两种储热水箱结构图,通过设计试验系统,搭建储热水箱分层特性测试试验台,收集了两种结构水箱在相同的初始水温、不同流量时水箱各层温度随时间的变化数据并绘制成图.同时基于热力学定律,分析对比了相同进口结构、相同初始进出水温差取出效率随时间的变化.在初始温度50℃、流量为1.1和4.2kg·min-1的工况下,对比了不同结构的MIX数对储热水箱分层性能的影响.     

Flow Uniformity of Roller-Type Quenching Machine

 Abstract: Three dimensional finite element flow field model of spraying pipe of roller-type quenching machine is built. The flow field under different structural parameters is computed. After grouping the nozzles, the spraying uniformity is analyzed under different water inlet pipe diameter, different water inlet pipe distance, nozzle diameter, nozzle distance. And the spraying intensity absolute deviation and relative deviation are computed under different conditions. The effect rule of different structural parameters to cooling uniformity is obtained. The results provide theoretical support for improving production quality and optimizing cooling device design.     

Bench-Scale Investigation of Inclined Dense Jets

In this work experimental data on the geometry of dense inclined jets issuing in a lab-scale glass rectangular tank are presented. The surrounding fluid was always tap water at room temperature while the dense jets were water solutions of NaCl. Four parameters were changed in the experiments, namely nozzle diameter and inclination, and jet density and flow rate. Jet trajectories were revealed by a colored tracer. Images of the jet were recorded by a digital camera and then further digitally processed, eventually resulting in a time-averaged tracer intensity field. All the jet geometrical parameters, once normalized, were found to be very well correlated to the densimetric Froude number. Moderate jet viscosity variations were found to not significantly affect jet behavior. The reported data allow a quick and easy estimation of maximum rise level, position of the trajectory maximum, and impact point distance of dense jets issued at different angles above the horizontal.     

Fluid flow in pachuca (Air-Agitated) tanks: Part II. Mathematical modeling of flow in pachuca tanks

A generalized mathematical model that combines Bernoulli’s equation and thek-ε model of turbulence, using only the gas flow rate and tank geometry as inputs, has been formulated to predict the fluid flow pattern in industrial-scale full-center-column Pachuca tanks. Predictions from this model reproduce reasonably well the trends that were observed in experiments when design and operating parameters, such as superficial air velocity and tank height/tank diameter ratio, were varied. Results from these calculations indicate that design parameters, such as tank height/tank diameter and draft tube/tank diameter ratios, have a significant effect on the flow pattern in full-center-column Pachuca tanks at large tank diameters or small tank height/tank diameter ratios.     

Scour due to Crossing Jets at Fixed Vertical Angle

Plunge pool scour is an important topic in hydraulic structures design. Numerous studies have been done in past years to understand the scour phenomenon due to plunging jets. These studies finally aimed at reducing the risk of structural undermining and collapse. Scour holes created under various hydraulic and geometrical conditions were analyzed for both two-dimensional and three-dimensional cases, and methods to reduce the scour were also investigated. In the current study, an attempt was made to quantify the feasibility of using crossing jets. The scour process was analyzed, and various relationships were presented to predict the main geometrical parameters, i.e., maximum scour hole depth, scour hole length, and scour hole width. Scour profiles were also compared with those due to an equivalent single jet. The main parameters on which the scour geometry depends were found as the densimetric Froude number of the jet, the crossing angle between the jets, the distance between the crossing point and the water surface level, and the water depth. All experiments have been carried out for a fixed vertical angle of 45°.     

高炉风口参数的设计探讨

风口是高炉送风系统的重要设备之一,通过对高炉风口参数进行分析探讨,论述了风口数目,风口高度,风口角度、长度,风口直径对高炉冶炼操作、生产技术经济指标的影响,并从设计角度提出了风口参数的设计、计算参考数据和建议。     

Experimental Study of Sand and Slurry Jets in Water

This paper presents the results of an experimental study of turbulent sand jets and sand-water slurry jets impinging vertically into a stagnant water body. The jets contained silica sand with a median diameter D50 of 206?μm, and with an initial concentration 0.60 by volume for the sand jets, and 0.055–0.124 by volume for the slurry jets. The jets had densimetric Froude numbers between 2.0 and 5.94. The sand concentration and velocity profiles were measured simultaneously using a novel fiber optical probe, up to a distance of 130do for sand jets, and 65do for slurry jets, where do is the jet diameter at the water surface. The jets were found to have self-similar Gaussian profiles. The centerline sand concentration within the jets was found to decrease rapidly, following trends similar to single phase plumes. The centerline sand velocity profile decreased significantly before reaching a plateau region. The “terminal” centerline sand velocity within this region varies somewhat depending upon sand mass flux, and is between 0.32 and 0.43 m/s. The spreading rates of the jets were found to vary with the particle Froude number. Within the sand jets and the higher Froude number slurry jet, the sand concentration had a smaller spreading rate than the velocity. The other slurry jets had equal concentration/velocity spreading rates. The momentum flux of the sand within the jets was found to decrease sharply, followed by a constant flux below a depth of 25 to 30 jet diameters.     

Penetrability of impinging gas jets in molten steel bath

An experimental study is carried out to determine the penetrability of impinging gas jets in molten steel baths of BOF and combined blown steelmaking. Depth and diameter of the depression produced by an impinging single jet or multi-nozzle jets are measured and correlated successfully with dimensionless momentum flow rate number. The equations are represented in the form of a nomogram by which the depth and diameter of the depression in a molten steel bath during the blow can be determined from easily available top blowing parameters.     

Measurement of physical characteristics of bubbles in gas-liquid plumes: Part II. Local properties of turbulent air-water plumes in vertically injected jets

The structural development of air-water bubble plumes during upward injection into a ladle-shaped vessel has been measured under different conditions of air flow rate, orifice diameter, and bath depth. The measured radial profiles of gas fraction at different axial positions in the plume were found to exhibit good similarity, and the distribution of the phases in the plume was correlated to the modified Froude number. Different regions of flow behavior in the plume were identified by changes in bubble frequency, bubble velocity, and bubble pierced length which occur as bubbles rise in the plume. Measurement of bubble velocity indicates that close to the nozzle the motion of the gas phase is strongly affected by the injection velocity; at injection velocities below 41 m/s, the velocity of the bubbles along the centerline exhibits an increase with height, while above, the tendency reverses. High-speed film observations suggest that this effect is related to the nature of gas discharge,i.e., whether the gas discharge produces single bubbles or short jets. In this region of developing flow, measurement of bubble frequency and pierced length indicates that break-up of the discharging bubbles occurs until a nearly constant bubble-size distribution is established in a region of fully developed flow. In this largest zone of the plume the bubbles influence the flow only through buoyancy, and the spectra of bubble pierced length and diameter can be fitted to a log-normal distribution. Close to the bath surface, a third zone of bubble motion behavior is characterized by a faster decrease in bubble velocity as liquid flows radially outward from the plume.     

Plasma spraying of ceramic particles in argon-hydrogen D.C. Plasma jets: Modeling and measurements of particles in flight correlation with thermophysical properties of sprayed layers

The behavior of alumina or stabilized zirconia particles in flight in Ar−H₂ d. c. plasma jets (up to 40 kW) has been studied. Measurement of the temperature distributions in the plasma jets (by emission spectroscopy) has shown the importance of the electrodes and are chamber designs on the length and diameter of the jets. The important cooling effect of the surrounding air has also been shown, and the parameters controlling it have been studied. Modeling of the momentum, mass, and heat transfers between plasma and particles as well as measurements of the trajectory, velocity, surface temperature distributions, and particle evaporation have enabled us to determine the influence of the different paramters, such as size and injection velocity distributions, particle morphology,etc., on the particle molten state upon impact. These calculations and measurements on the particles in flight have been correlated to some physical properties of deposits. This paper is based on a presentation made in the T.B. King Memorial Symposium on “Physical Chemistry in Metals Processing” presented at the Annual Meeting of The Metallurgical Society, Denver, CO, February, 1987, under the auspices of the Physical Chemistry Committee and the PTD/ISS.     

无填料喷雾冷却塔的发展及改进思路

介绍了无填料喷雾冷却塔的发展过程，与传统的填料式冷却塔的结构和冷却效果进行比较，针对喷雾冷却塔结构上的缺点，提出几点改进思路。