Bubbling Jet Along Vertical Flat Plate

Dispersion of bubbles in a molten metal bath and the induced flow strongly influence the performance of gas-agitated steelmaking processes. Unfortunately, measurements of the bubble and molten metal flow characteristics are quite difficult in real steelmaking processes. Hence water model experiments have been extensively employed for such investigations, as discussed in detail in Chap. 1 [17,18]. The vessels used for such model experiments are usually fully wetted by water, whereas in the actual steelmaking processes, the wettability of the reactor wall is generally poor. When the wall material, i.e., refl actory, is wetted by the molten metal, some chemical reactions may occur between them, and consequently, the molten metal may be contaminated by the refractory. As mentioned earlier, the wettability is evaluated in terms of 0a [19]. 

13 Observed and calculated bubble shapes in water-air system 

Very little is iaiown about the effects of wettability of a plate on bubble and molten metal flow characteristics except for the frequency of bubble formation, /b [20-22], These studies have shown that the frequency of bubble formation from a single-hole nozzle or a porous nozzle that is not wetted by the liquid is significantly different from that from a single-hole nozzle of good wettability. This result suggests that the bubble and liquid flow characteristics near a vertical flat plate would 

5 X 10 m was placed at the center of the bottom of the vessel. A flat plate was vertically situated beside the nozzle. The origin of the Cartesian coordinate system (x, y, z) was placed on the center of the nozzle tip. 

The advancing contact angle 0a was measured with the sessile drop method [26]. Two flat plates were used a copper plate with 0a = 62° (good wettability) and an acrylic plate coated with paraffin with 0a = 104° (poor wettability). 

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In applying this equation to bubbling wall jets along a vertical flat plate, yH,max/2 should be expressed as follows ... 

In the buoyancy region, the nondimensional distribution of M/iimax in the bubbling wall jets along the vertical flat plate with good wettability is approximated by... 

Sonoyama N, Iguchi M (1999) Wettability effects on bubble characteristics in a bubbling wall jet along a vertical flat plate. ISIJ Int 39 673-679... 

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