磁压约束控制金属液面波动和渣金界面行为的基础研究

It is a key problem for continuous casting process to reasonably control the fluctuation on free surface. An original idea was put forward to control the free surface oscillation and surface deformation, that is, mangetic pressure was introduced and utilized to control free surface oscillation and surface deformation. The experimental and nmerical simulaiton methods are both used in our researches. Through reseaching the distribution of magnetic field and magnetic force, the distribution characteristics of the magnetic pressure is revealed. The fluid flow and free surface oscillation behavior caused by the applied magnetic field is also investigated. The oscillation characteristics of free surface investigated in detail, as a result, the fundametal theory and methods about how to use magnetic pressure to damping the free surface oscillations is to be obtained. Some efforts are also made to explore the mechanism of mangetic pressure controling to the free surface deformation. The bubbles movement and distribution at the vicinity of free surface is considered and investigated after imposing magnetc pressuue, and the influence of gas volume fraction on the damping effect of mangetic pressure is also studied. The damping effect of magneic pressure on slag/metal interface instability is investigated, then the crital slag/metal interface instable conditin is explored and obtained. The mainly considered influencing factors are impacting degree of jet flow, magnetic intensity and freqency, velocity of metal on free surface, fluctuation magnitude, and the characteristic dimension, etc. Some rational parameters are to be obtained for stable free surface. The research results of this item are significant for forming and perfecting the elementary theory about electromagnetic metallurgy, exploiting innovative metallurgy technique and realizing high efficiency continuous casting process.

合理控制液面波动是连铸过程中非常关键的问题。本项目提出了利用磁压约束作用来控制液面波动和变形的设想。采用实验和模拟相结合的方法，通过研究不同磁场下的磁场和电磁力分布规律，揭示磁压分布基本特征。探索磁压约束下磁致流体流动和液面波动的特性。系统研究磁压约束下液面波动行为，获得利用磁压约束控制液面波动的基本理论和方法，建立液面波动基本关系式。探索磁压对液面变形的作用机理；揭示磁压约束对气泡运动和分布行为的影响规律以及含气率对磁压约束作用的影响规律；研究磁压约束对渣金界面波动控制基本规律，探索磁压控制下渣金界面失稳条件和卷渣机理；考察熔池特征尺寸、液面流速、作用距离、磁场强度和频率等因素对磁压约束效果的影响规律，获得参数的匹配关系。本项目的研究对揭示磁压约束机理、完善电磁冶金基本理论、开发新的冶金新技术和实现高效连铸具有迫切的现实意义。

合理控制液面波动是连铸过程中非常关键的问题。对磁压约束下的液面行为进行了研究。开发了磁-流场双向耦合程序。程序可用于磁场作用下液面行为、流动和渣金界面行为及多相流动的耦合分析。建立了循环流动装置和连铸热模拟实验平台；该平台可用于电磁连铸结晶器内流动和液面行为的热态实验研究。. 研究了不同磁场发生器的电磁特性，获得了相关参数对磁场特性的影响规律，为高效磁场发生器的设计提供了思路。约束磁场会在金属液面产生垂直于液面的磁压力。液面形状与磁压分布密切相关。磁场作用会引起液面波动，波动随着电流强度增加而加剧，但波动振幅小于1 mm。电流强度越大，磁压控制液面变形的能力越强。大于20 kHz后，磁压控制液面变形的能力不再受频率影响。导线平行于结晶器宽面的磁场发生器的效率较高。. 获得了磁约束下鼓包变形的基本规律。验证了磁约束抑制液面波动的可行性。磁约束鼓包变形的机理为磁压与重力的叠加效应和磁压对射流速度的抑制作用。磁约束可有效抑制鼓包变形和液面波动，单主频波动变为多主频的微小波动；抑制效果随着磁压增加而增强。适当强度和作用范围的磁压力可完全抑制鼓包变形。磁场作用面积与变形面积之比约为0.8时，抑制效果较好。磁压抑制效率与磁场强度近似呈线性关系，较大的Rω可提高抑制效率。施加磁压能改善钢包内的流场。获得了磁压作用对渣金界面和渣眼行为的影响规律。磁压强度与喷吹强度匹配时，可达到消除渣眼的效果。. 研究了磁约束作用对结晶器内液面波动和内部流动的影响规律；分析了磁场特性与液面波动抑制效果间的关系。揭示了相关参数对液面行为的影响规律。确定了磁场发生器的类型，对发生器提出了疏密设计的设计方案。提出了合理的线圈设置位置。电流强度在一定范围内时磁约束作用对结晶器内金属液面变形和波动的抑制效果最好。获得了磁约束强度与拉速、水口浸入深度和水口倾角的匹配关系。高拉速条件下施加磁压约束更有利于发挥磁压约束的冶金效果。磁压力对结晶器内部流动的影响不大。. 项目研究拓展了电磁冶金技术，为控制金属液面行为提供了一种新的电磁控制思路和方法，具有重要的理论和实用价值。