Computational Fluid Dynamics Simulation of Supersonic Oxygen Jet Behavior at Steelmaking Temperature
- PDF / 441,856 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 96 Downloads / 179 Views
ONIC gas jets are used widely in basic oxygen furnace (BOF) and electric arc furnace (EAF) steelmaking for refining the liquid iron inside the furnace. Supersonic gas jets are preferred to the subsonic jets because of the high dynamic pressure associated with it, which results in a greater depth of penetration and in better mixing. Laval nozzles are used to accelerate gas jets to supersonic velocities of around 2.0 Mach number in steelmaking.[1] The supersonic gas jets generate droplets upon impingement on the liquid melt, which is known as splashing. Droplet generation has both beneficial and detrimental effects. The droplet increases the interfacial area, which in turn, increases the refining rate.[2] On the other hand, it may cause a wearing of refractories or a skulling on the mouth of the vessels and lances, which can result in a loss of production.[3–5] Therefore, it is necessary to understand the behavior of the supersonic gas jets in a high temperature environment to determine the optimum processing conditions. Various experimental and numerical investigations of the behavior of the supersonic oxygen jet after emerging MORSHED ALAM, Ph.D. Student, JAMAL NASER, Senior Lecturer, and GEOFFREY BROOKS, Professor, are with the Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn, PO Box H-38, Victoria 3122, Melbourne, Australia. Contact e-mail: [email protected]. Manuscript submitted December 16, 2009. Article published online February 4, 2010. 636—VOLUME 41B, JUNE 2010
from the Laval nozzle have been reported in the literature.[6–12] But only Sumi et al.[8] experimentally studied the behavior of the supersonic oxygen jet at three different ambient temperatures—285 K, 772 K, and 1002 K. The results showed that velocity attenuation of the jet was restrained, and the potential flow core length was extended under high temperature conditions. The potential flow core length was defined as the distance from the nozzle tip to the point where the magnitude of the nozzle exit velocity remains unchanged. Numerical simulations of the supersonic oxygen jet behavior at a high ambient temperature carried out by Allemend et al.,[6] Tago and Higuchi,[9] and Katanoda et al.[12] also showed an increase in the potential flow core length, but their results were not validated against experimental data. When a supersonic jet exits from a Laval nozzle, it interacts with the surrounding gas to produce a region of turbulent mixing as shown in Figure 1. This process results in an increase in jet diameter and a decrease in jet velocity with an increasing distance from the nozzle exit. However, in a high-speed jet, the mixing of the jet with its surroundings is suppressed, and the growth rate of the turbulent mixing region is reduced.[13] It became known in the late seventies that the standard ke model[14] gives a poor prediction of the mean velocity profiles of the highspeed turbulent axisymmetric jets.[15] This result occurs because the standard ke model lacks the ability to reproduce the observed reduction
Data Loading...
