Model study of turbulence structure in a bottom blown bath with top slag using conditional sampling

Abstract

MANABU IGUCHI, TADATOSHI NAKATANI, and HIROSHI UEDAWater model experiments were carried out to study the effect of top slag on the turbulence structure in a molten steel bath agitated by bottom gas injection. Water and silicone oil were used as models of molten steel and slag, respectively. Air was injected through a single-hole bottom nozzle so that the reverse emulsification of the silicone oil occurred at the silicone oil-water interface. Silicone oil droplets thus generated were carried deeply into the lower water layer. Turbulence measurements were made using a two-channel laser Doppler velocimeter (LDV) in the presence and absence of the top oil layer. A conditional sampling method called the four-quadrant classification method was applied to detect large scale coherent motions in the vertical bubbling jet as well as in the recirculation region. The structure and intensity of turbulence inside the bubbling jet were strongly affected by bubbles. In the absence of the top oil layer, higher momentum fluid motions directed from the centerline of the bubbling jet to the sidewall of the vessel were mainly responsible for the turbulence production in the bubbling jet, while lower momentum fluid motions directed from the sidewall toward the centerline governed the turbulence production in the recirculation region. On the other hand, in the presence of the top oil layer, the coherent motion in the bubbling jet was also affected slightly by the top layer except for the center of the bubbling jet, whereas any distinguished coherent motion was not observed in the recirculation region, and hence, turbulence production was weak there.

Turbulence structure of bottom-blowing bubbling jet in a molten Wood’s metal bath

“…u The measured value of this turbulence intensity also obeyed a Gaussian distribution and took a value of approximately 0.55 on the centerline of the bubbling jet. The same centerline value of u' rms / cl was obtained at every other axial u position, which was larger than the value in an air-water bubbling jet [12] by approximately 10 pct. Figure 8 indicates that the radial turbulence intensity (v' rms / cl ) on the centerline of the He-Wood's metal system u was approximately 1.25 times as large as that for the airwater bubbling jet.…”

“…[16] The axial mean velocity of liquid flow also follows a Gaussian distribution in the presence of wobbling bubbles. [12] Under the present experimental conditions, the radial distribution of gas holdup had a plateau near the centerline of the bubbling jet and exhibited a mild peak outside the plateau. The reason for such a somewhat curious distribution of gas holdup can be explained as follows.…”

“…However, the mechanism of turbulence production was not mentioned. In this study, the four-quadrant classification method, [12] being one of the popular conditional sampling methods, [13,14] was adopted to elucidate the coherent structure of turbulence or the mechanism of turbulence production in a vertical He-Wood's metal bubbling jet. Wood's metal flow was provided in a previous article, [11] some aspects of that information will be reproduced here.…”

Transient Fluid Flow Phenomena in a Gas Stirred Liquid Bath with Top Oil Layer—Approach by Numerical Simulation and Water Model Experiments

“…As general approaches there are some literatures reported about the qualitative analysis about the effect of slag layer on the behavior of melt flow characteristics during gas bubbling from the bottom of the ladle. [4][5][6][7][8] Those The flow characteristics in a gas stirred ladle with oil layer were investigated with the help of water model experiments and numerical simulation. The oil layer has a great influence on the fluid flow and mixing behavior in the ladle.…”

Fluid dynamics studies related to bottom blown copper smelting furnace

“…Figure 2-12 Experimental apparatus in Iguchi's research [45][46][47][48] Figure 2-13 Conductivity electrode in Iguchi's research [45][46][47][48] In order to study fluid flow phenomena in liquids of varying kinematic viscosities, Iguchi built up another physical model [49][50][51] . Transparent oily liquids such as silicone oil were usually used to simulate slag.…”