Abstract
The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa.
Highlights
Inside the industrial buildings, most of production technologies cannot completely prevent noxious substances from sending out to the air
In the practical production technologies, the inner diameters of heat sources were different, which had an effect on the flow field of high-temperature annular buoyant jets
The middle peak velocity was mainly caused by the vortex with buoyant jets at the sides expanding to the center, while peak velocities at the sides were the common characteristics of the buoyant jets; namely, the axial velocity of buoyant jets reached the maximum gradually when acceleration action due to buoyancy and velocity decay due to entrainment were in equilibrium
Summary
Most of production technologies cannot completely prevent noxious substances from sending out to the air. High-temperature heat source induced annular buoyant jets in large space widely exists in the iron and steel, coking, and machinery industries. It may be produced by pouring molten iron into filling tank in blast furnace plant or dumping steel slag in deslagging plant. During the process of dumping high-temperature materials, strong shear force may be produced under impact and squeezing action. Induced by the shear airflow and high-temperature heat source, the shear force makes the dusty airflow generate a strong annular buoyant jet upward. The annular buoyant jet shows similar law to that of circular buoyant jet when developed at a certain stage, significant differences still exist between them in space relevant to industrial production
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