Numerical Simulation of Molten Steel Flow Field in a Ladle Induced by Low-Frequency High-Power Ultrasound

To encourage the use of ultrasound in the calcium treatment of molten steel, this study utilizes the volume-of-fluid (VOF) method combined with a mixture model to analyze the distribution of the flow field in molten steel when ultrasound is applied. The effects of low-frequency, high-power ultrasound on the pressure field, volume fraction of cavitation bubbles, velocity distribution, and turbulence intensity are investigated. The results reveal a pattern of alternating positive and negative pressure in the pressure field during each cycle, with the lowest pressure measuring -9.63 x 104 Pa at 96 kW. The cavitation bubbles are concentrated in the intense cavitation area beneath the ultrasonic probe, exhibiting a maximum volume fraction of 2.50 x 10-2. The axial velocity peaks at the central axis, whereas the radial velocity is negligible. The maximum axial velocity increases from 0.36 m/s at 48 kW to 0.82 m/s at 120 kW. This velocity trend mirrors the turbulence intensity distribution, with the highest turbulence intensity of 276 at 96 kW. These findings provide a theoretical basis for low-frequency, high-power ultrasound to improve the calcium treatment of molten steel. The outcomes of the numerical simulation closely align with the experimental results, substantiating their reliability through a comparison with published studies. The volume-of-fluid method coupled with the mixture model is proposed to quantitatively characterize the evolution of the pressure field, velocity field, turbulence intensity, and cavitation bubble distribution under an ultrasonic field. This study provides a theoretical basis for optimizing the molten steel calcium treatment technology and improving the calcium yield and stability.image (c) 2024 WILEY-VCH GmbH