Effect of Shrouding Gas Temperature on Characteristics of a Supersonic Jet Flow Field with a Shrouding Laval Nozzle Stru
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THE Laval nozzle is widely used in the basic oxygen furnace (BOF) and electric arc furnace (EAF) steelmaking processes to deliver the oxygen to the molten bath. During this process, the kinetic energy of the molten bath is increased by the oxygen jet, and the oxidation rates of carbon and phosphorus are also improved. Therefore, the oxygen jet has an important role in facilitating the stirring effect, dephosphorization and decarburization processes.[1–3] After the oxygen jet passes though the Laval nozzle, its velocity is accelerated to approximately 2.0 Mach number, with the oxygen velocity then decelerating because of its entrainment by the ambient gas stream. Coherent jet technology has been proposed as a means to improve the mixing ability of the oxygen jet and prolong its velocity potential core.[4] The key to coherent jet technology is formation FUHAI LIU and DONGBAI SUN are with the National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083, China. Contact email: [email protected] RONG ZHU is with the Beijing Key Laboratory of Research Center of Special Melting and Preparation of High-end Metal Materials, University of Science and Technology Beijing, Beijing 100083, China. YILIN LI is with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China. Manuscript submitted October 11, 2017.
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of a high-temperature shrouding jet formed by the combustion of CH4. This serves to create a low-density environment in the center of the shrouding jet, which suppresses the entrainment phenomenon that occurs between the main oxygen jet and ambient gas. Consequently, the adoption of coherent jet technology could result in significant metallurgical and operational improvements to the steel-making process.[5,6] Many investigations have been carried out in the flow fields of coherent jets at different oxygen jet temperatures, shrouding jet flow rates and environmental conditions.[7–9] Liu et al.[10] showed the oxygen preheating method could be used to increase the effect ability of the supersonic oxygen jet using a series of results of experimental and simulation experiments. Alam and Zhao et al.[11,12] analyzed the effect of shrouding gas parameters on the flow field of coherent jets under different ambient temperatures. Mahoney[13] presented the characteristics of the traditional supersonic jet and coherent jet at sub-atmospheric environmental pressure in a series of combustion experiments. Meidani et al.[14] used room-temperature compressed air as the shrouding jet to research its impact on the mixing ability of the main oxygen jet. However, little research has been carried out on the effect of the shrouding nozzle structure on the flow field of a coherent jet. The theory of hydromechanics[15] predicts the environmental density at the center of the shrouding jet will decrease as the shrouding jet velocity increases, which will lead to its velocity potential core
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