Fundamental Research On The Jet Characteristics Of Porous Oxygen Lances For Converters

The jet characteristics of a supersonic oxygen lance nozzle are important for understanding the interaction between the oxygen lance jet and the molten pool,as well as for guiding production practice.Using the oxygen lance of a 260-ton converter in a steel plant as the research object,a three-dimensional geometric model was established using ICEM software,and the jet characteristics of a porous oxygen lance were studied using CFD numerical simulation under different Mach numbers,nozzle inclinations,ambient temperatures,and inlet pressures.The theoretical formula of velocity attenuation in a multi-jet flow field is perfected and established on the basis of predecessors’theories.The numerical simulation results of porous oxygen lance jet characteristics are compared to the semi-empirical formula results,and the synergistic effect of Mach number and nozzle inclination angle on jet attenuation is investigated.The scientific relationship between jet deflection,Mach number,and jet inclination angle is established,the jet centerline deflection calculation method is proposed,and the mathematical model of jet centerline linear velocity attenuation is improved.The following table summarizes the relationship between momentum transfer coefficient K_j,Mach number,and nozzle inclination.The correlation laws of momentum transfer coefficient K_j and section velocity distribution coefficientλ_j in supersonic section K₁and subsonic section are corrected as a result of the results.The following are the main conclusions:（1）The critical angle θ_e of the nozzle of a porous oxygen lance is 7.43～8.40,and the jet deflection of a porous oxygen lance with different nozzle inclination angles is different,and the deflection is obvious when it is less than the critical inclination angle.Increases in nozzle inclination,ambient temperature,and inlet pressure all reduce jet centerline deflection.（2）As the Mach number,nozzle inclination,ambient temperature,and inlet pressure increase,so does the momentum transfer coefficient K_j.The empirical formula for defining the velocity attenuation gradient K₁ and optimizing the momentum transfer coefficient K_j has more accurately described the supersonic jet flow field.（3）The section velocity distribution coefficientλ_j increases abruptly at the critical inclination angle and continues to increase as the nozzle inclination angle and Mach number increase.When the angle is less than the critical angle,the relationship coefficient betweenλ_j and K_j is 1.59;when the angle is greater than the critical angle,āis 1.87;in a high-temperature environment,ā=0.57;and under different inlet pressures,āis 1.82,with an error of 7.2%.（4）The velocity distribution of the jet flow field of the integral porous oxygen lance can be solved using the velocity attenuation gradient K₁,momentum transfer coefficient K_j,and cross-section velocity distribution coefficientλ_j.