Original Article

Numerical simulation on multiphase flow of hot metal with wear impeller during KR stirring process

School of Mechanical and Materials Engineering, North China University of Technology, Beijing 100144, PR China

^* e-mails: zhanglifeng@ncut.edu.cn;weichen@ncut.edu.cn

Received: 24 December 2024
Accepted: 14 May 2025

Abstract

Numerical simulations were employed to investigate the multiphase flow characteristics of the hot metal during the KR stirring process with various wear states of the stirring impeller. The shape and geometry of the impeller during the actual KR stirring process with different employed heats were quantitatively measured first. Then the effect of wear states of the impeller on the flow pattern of the hot metal, velocity distribution, induced vortex height and depth, turbulent kinetic energy, and turbulent energy dissipation rate were studied. As the number of employed heats increased from 0 to 280, the efficacy of the stirring impeller was diminished due to the erosion and metal shedding and the flow pattern was changed from the initial upper and lower circulation featuring multiple upper and lower circulations. The vortex height and depth were decreased from 0.646 m and 1.343 m to 0.004 m and 0.063 m, respectively. A speed dead zone was observed at the bottom of the impeller, with the volume of this dead zone increasing as the impeller erosion progressed. Moreover, regression formulas for the variation of the vortex depth (H_depth, m) and height (H_height, m), with the turbulent energy dissipation rate (ε, m²/s³) and impeller employed heats (N_heat) across the entire service lift of the impeller were proposed as

H_depth = { 1.32(0.557 − 0.0028 N_heat)^0.95     0 ≤ N_heat ≤ 120

         35.78 × 10^2.73N_heat^−2.2           120 < N_heat

H_height = { 2.31(0.557 − 0.0028N_heat)^2.27     0 ≤ N_heat ≤ 120

         713.22 × 10^4.8N_heat^−3.9           120 < N_heat.