基于CFD-DEM的高炉风口回旋区形状和传热特性数值模拟研究

采用计算流体力学-离散单元法(CFD-DEM)耦合方法,对高炉风口回旋区进行了数值模拟研究。首先通过与实验结果对比,验证了CFD-DEM模型的正确性;然后考察了不同气速对风口回旋区形状和传热特性及颗粒接触的影响。数值模拟结果表明:风口回旋区的大小和形状均受气速影响较大,在较大进气速度下,颗粒受到的曳力大于颗粒间的摩擦阻力并破坏颗粒间的桥力,形成较大尺寸的回旋区;且颗粒之间接触力较小,形成较大的空隙结构,更有利于热气体向周围扩散以强化传热。目前考察的三种气速结果表明:当气速为11m/s时,热量向下方传递速度最快;当气速为13m/s时,热量向上方传递速度最快;而当气速为15m/s时,热量向右方传递速度最快;此外,气速越大流态化越明显,颗粒间接触越少,接触力也越小。

CFD-DEM study on shape and heat transfer characteristics of the blast furnace raceway

Numerical simulation on the blast furnace(BF)raceway is carried out by using the coupled method of computational fluid dynamics and discrete element method(CFD-DEM).Firstly,the accuracy of the CFD-DEM model is verified by comparing numerical results with the experimental data.Then,influence of inlet gas velocities on the shape and heat transfer characteristics of the raceway is investigated.Numerical simulation results show that the size and shape of the raceway are greatly affected by the inlet gas velocity.At a higher inlet velocity,the bridge force between particles is destroyed,when the drag force of particles is greater than the friction resistance between particles,which can form a large raceway.The smaller the contact force between particles is,the larger the voidage is.Thus,it is more favorable for the diffusion of heat gas to the surrounding region,so as to enhance the heat transfer.It is also found that when the gas velocity is 11 m/s,the heat transfer speed to the downward direction is the fastest;when the gas velocity is 13 m/s,the heat transfer speed to the upward direction is the fastest;and when the gas velocity is 15 m/s,the heat transfer speed to the right side is the fastest.In addition,the larger the gas velocity is,the more obvious the fluidization is and the less contact between particles is,the smaller the contact forces will be.