共查询到19条相似文献,搜索用时 125 毫秒
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钢包底吹氩对钢水的运动、氩气泡在钢水中的迁移及夹杂物去除有重要影响。基于Fluent模拟软件建立了RH真空处理过程中钢包底吹氩的数值计算模型,对RH真空处理过程进行模拟分析,并对此模式下的钢水夹杂物尺寸及分布进行了取样分析。结果表明,RH真空处理过程中钢包底吹氩能有效增加钢包内钢水的流动速度,并减少钢包内部死区占比,同时,在一定程度上促进夹杂物的长大和上浮。另外,过大的钢包底吹氩气流量不但无法促使长大的夹杂物上浮被吸附,甚至还会导致钢水被二次污染。数值模拟及现场取样分析表明,RH真空处理过程中需采用适当的氩气流量钢包底吹氩操作,同等条件下,流量取值以5 m3/h为宜。 相似文献
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为了推断高压条件下气体在液体金属中的存在形态和运动形态,通过水模拟试验研究压强、底吹流量对气泡形状、尺寸、数量及"渣眼"尺寸的影响,结果表明:随着底吹流量增加,高压条件下的气泡比常压条件下的气泡更趋向于正圆形,气泡直径平均值变小,气泡数量增多,气泡形状和直径在底吹流量为4 L/h时变化最为明显;当底吹位置和底吹流量不变时,随着压强的增加,气泡形状逐渐趋向于正圆形,气泡直径逐渐变小,气泡数量逐渐增多,"渣眼"面积逐渐减小。在常压和高压条件下,底吹流量超过5 L/h之后,气泡形状和直径平均值就不再有明显变化。当底吹流量为4 L/h时,压强升高到0.5 MPa后,气泡形状和直径平均值变化幅度较小。为高压条件下冶炼提供数据参考。 相似文献
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气泡在液体中形成的试验研究 总被引:9,自引:0,他引:9
本文首次采用摄录象设备,以空气和水为工质,在大气条件下,系统地研究了气体由小直径导管引入液体时的气泡形成和脱离。考察了气体流量,导管内径和气体引入方向对气泡脱离尺寸的影响。 相似文献
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依据热量平衡原理,计算得到了某种气体喷吹流量下形成的"蘑菇头"直径为60.2mm。使用商业软件FLUENT将"蘑菇头"区域设置为多孔介质,利用VOF模型模拟了"蘑菇头"存在时气泡的产生、生长、直至破裂的过程。对比没有"蘑菇头"时气泡的变化,模拟发现,"蘑菇头"的存在对流动过程的影响较大。"蘑菇头"的存在使气泡体积与表面积更大,形状更接近球形,且在炉内停留时间更长,有利于炉内气体与熔体的流动与充分反应。 相似文献
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Ruhrstahl-Hereaeus (RH)上升管内的气液两相流是整个装置的重要动力源,并对钢液的流动、混匀及精炼过程有重要影响.上升管及真空室内的气液两相流决定了钢包内钢液的流动状态,为了研究真空室及上升管内气液两相流,通过1:6的300 t RH的物理模型模拟了RH上升管及真空室内气泡行为过程,并测量了RH循环流量的变化用于计算上升管内含气率以及气泡运动速度最终得到气泡在真空室内的停留时间,同时记录了气泡在真空室内的存在形式.气泡在真空室的存在形式的主要影响因素为提升气体流量,研究发现了气泡从规则独立的大气泡经历聚合长大,碰撞破碎成小气泡,最后变成小气泡和不规则大气泡共存的现象.液面高度达到80 mm之后,气泡在真空室内的停留时间达到一个平衡值,不再随真空室液面高度的增加而发生改变.当提升气体量达3000 L·min-1,气泡停留时间减小趋势弱,对应3000 L·min-1情况下,真空室内气泡开始聚合长大.研究认为对于300 t RH的真空室液面高度应为80 mm,提升气体量应在3500 L·min-1左右,优化后,脱碳时间由原工艺的21.4 min缩短至现工艺的17.5 min. 相似文献
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为了分析钢包内离散气泡和界面波动对脱硫效率的影响,本文采用数值模拟法,选择大涡模拟和离散相模型,结合界面追踪法建立三维瞬态渣-金-气三相流模型,模拟气泡行为及渣层变化规律,同时利用相间传质求解发生于钢包内渣-金界面处的脱硫过程.本模型设置压力为101.325kPa,反应温度为1873K,考虑了气泡运动、变形、破碎、碰撞等行为对脱硫的影响,为预测底吹钢包搅拌过程的脱硫、卷渣及气泡行为提供了理论依据.计算结果表明,初始直径为0.001m的气泡吹气稳定后最大直径达到0.009m,并且随着吹气量的增加,硫的传质速率也不断增大,且喷嘴上方渣-金界面处的脱硫速率较快. 相似文献
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以100t单孔底吹氩钢包为原型,应用三维连续性方程、动量N-S方程及湍流κ-ε双方程模拟了底吹氩过程中钢包内的钢液流动状态。利用Mixture多相流模型对单孔吹氩(0~700 L/min)过程进行数值模拟,对比分析插入直径691.05 mm,深650 mmn浸渍管前后钢包内的流动状态和钢液表面的卷渣。结果表明,无浸渍管时,临界卷渣吹气量为102 L/min,插入浸渍管后,临界卷渣吹气量增大到217 L/min。插入浸渍圆筒可以在增加吹氩量的条件下提高钢液搅拌效果,加速钢液混匀。 相似文献
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摘要:通过水模型实验研究了上水口环形吹氩工艺下中间包和结晶器内气泡形貌,并结合数值模拟分析了透气砖位置、拉坯速度和吹氩量对中间包和结晶器内气泡尺寸、气泡迁移和中间包近液面钢液流动的影响。结果表明:上水口环形吹氩形成以塞棒为中心的圆台状气泡羽流,气泡浓度沿径向向外逐渐减少;附壁效应使得气泡羽流偏向塞棒壁面流动,增大气泡的碰撞聚并概率和近塞棒壁面的羽流上升速度,对中间包液面产生较大冲击作用;同时,部分细小气泡会随钢液进入水口及结晶器内部;增大吹氩量,中间包内环形气泡羽流中气泡数目明显增多,中间包近液面钢液上升速度增大;增大拉坯速度,环形气泡羽流的宽度和气泡数量逐渐减小,近液面速度减小;增大透气环距水口中心距离,中间包内气泡弥散度增大,环形气泡羽流宽度也随之增大,气泡羽流对中间包液面冲击作用减弱;增大吹氩量和拉坯速度、减小透气环距水口中心距离,进入结晶器的气量和气泡尺寸逐渐增大。实验条件下,透气环内外径为110mm/140mm、拉坯速度为1.2m/min时,吹氩量为4L/min较为合适。 相似文献
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The water model experiments were carried out to study the bubble morphology in the tundish and mold with the process of annular argon blowing at tundish upper nozzle. The effects of the position of gas permeable brick, the casting speed and the argon flow rate on the bubble size distribution, the bubble migration behavior and the flow behavior of liquid steel near the liquid level in tundish were further investigated, coupled with the numerical simulation. The results show that with the process of annular argon blowing at tundish upper nozzle, a frustum cone shaped bubble plume can be formed around the stopper rod. The concentration of argon bubbles gradually decreases outward along the radial direction of the stopper rod. Owing to the wall attached effect, the bubble plumes float upward along the stopper rod, which can increase the collision probability between bubbles and the velocity of bubble plumes, causing a larger impact strength on the liquid level in tundish. In addition, a part of small bubbles are wrapped into the nozzle and the mold due to the drag force of liquid steel. With increasing argon flow rate, the number of bubbles in annular bubble plumes and the vertical velocity of liquid steel near the liquid level in tundish increase significantly. With increasing casting speed, the width and the bubble number of annular bubble plumes gradually decrease, leading to a decrease of the vertical velocity of liquid steel near the liquid level in tundish. Increasing the distance between the annular gas permeable brick and the center of tundish upper nozzle, the dispersion of bubbles and the width of bubble plumes increase, and the impact strength of bubbles acting on the liquid level in tundish becomes weaker. As the argon flow rate and the casting speed increase, and the distance between the gas permeable brick and the center of tundish upper nozzle decreases, the gas volume and bubble size in the mold increase. Under the experimental conditions, when the inner and outer diameters of the annular gas permeable brick are 110mm and 140mm, respectively, and the casting speed is 1.2m/min, the appropriate argon flow rate is 4L/min. 相似文献
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针对浇注钢包环出钢口四孔透气塞吹氩控制下渣工艺,建立了某钢厂130 t钢包三维DPM-VOF耦合数学模型以计算浇注钢包下渣过程,并通过冷态实验验证了该模型的有效性。利用该模型研究了不同偏心率对下渣行为的影响,揭示了该工艺控制下渣的行为规律,并分析了吹氩流量对控制下渣的影响。结果表明,随着偏心率的增大,不同浇注高度下的最大切向速度减小,汇流漩涡临界高度降低。环出钢口四孔透气塞吹入氩气后,气泡流股的汇聚有效地减弱了水口上方钢液的周向旋转速度,大幅降低了汇流漩涡下渣临界高度。4个气泡流股的气液两相流会抑制流向水口钢液的径向流动速度,由排流沉坑引起的下渣也得到明显抑制。随着吹氩流量的增加,下渣临界高度呈降低趋势。就本研究而言,控制下渣的最佳吹氩流量为30 L/min。 相似文献
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Bubble formation during gas injection into turbulent downward-flowing water is studied using high-speed videos and mathematical
models. The bubble size is determined during the initial stages of injection and is very important to turbulent multiphase
flow in molten-metal processes. The effects of liquid velocity, gas-injection flow rate, injection hole diameter, and gas
composition on the initial bubble-formation behavior have been investigated. Specifically, the bubble-shape evolution, contact
angles, size, size range, and formation mode are measured. The bubble size is found to increase with increasing gas-injection
flow rate and decreasing liquid velocity and is relatively independent of the gas injection hole size and gas composition.
Bubble formation occurs in one of four different modes, depending on the liquid velocity and gas flow rate. Uniform-sized
spherical bubbles form and detach from the gas injection hole in mode I for a low liquid speed and small gas flow rate. Modes
III and IV occur for high-velocity liquid flows, where the injected gas elongates down along the wall and breaks up into uneven-sized
bubbles. An analytical two-stage model is developed to predict the average bubble size, based on realistic force balances,
and shows good agreement with measurements. Preliminary results of numerical simulations of bubble formation using a volume-of-fluid
(VOF) model qualitatively match experimental observations, but more work is needed to reach a quantitative match. The analytical
model is then used to estimate the size of the argon bubbles expected in liquid steel in tundish nozzles for conditions typical
of continuous casting with a slide gate. The average argon bubble sizes generated in liquid steel are predicted to be larger
than air bubbles in water for the same flow conditions. However, the differences lessen with increasing liquid velocity. 相似文献