Effect of Shrouding Gas Parameters on Characteristics of Supersonic Coherent Jet

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SUPERSONIC oxygen jet is widely used in the steelmaking processing of basic oxygen furnace and electric arc furnace. High speed oxygen injects into the bath and reacts with the liquid steel, accelerating metallurgy process. Considering the impinging depth of molten bath, the Laval nozzles with Mach 2.0 are used in steelmaking.[1,2] The supersonic jet will produce a turbulent mixing region from the nozzle exit due to the interacting with the surrounding environment gas. There is an increase in the jet diameter and a decrease in the jet velocity, and it decreases the momentum and impact force of jet.[3,4] In order to reduce the momentum loss and prolong the length of potential core, the coherent jet technology is proposed in the steelmaking process.[5–7] The principle of coherent jet technology is that the main supersonic jet is surrounded by high temperature and high speed shrouding gas.[8] Because of the shrouding gas envelope, the entrainment of the surrounding environment gas into the supersonic jet is reduced. The velocity attenuation of main supersonic jet is delayed. The coherent jet has been used in the steelmaking for many years. There are some studies[9–12] about the

coherent jet. Mahoney[13] investigated the potential core length of supersonic coherent jet under different shrouding fuel and oxygen flow rate condition. Meidani[14] studied the supersonic jet with compressed air as shrouding gas through the water model experiment. Alam[15] computed the fluid character of supersonic coherent jet with the flame and Liu[16] investigated the effect of ambient and oxygen temperature on flow field characteristics of coherent jet by simulation and experiment. In their studies, the research results are mainly focused on the effect of shrouding gas or flame on the supersonic jet character, but there are very few researches about the effect of the shrouding gas parameters on the flow field of supersonic jet. To overcome these limitations, the effect of the shrouding gas at a specific temperature, pressure, and density on the supersonic jet is studied in this paper, the relationship between the shrouding gas parameters and the supersonic region length of jet will be provided.

II. EXPERIMENT EQUIPMENT AND NUMERICAL SIMULATION A. Experimental Equipment

FEI ZHAO and DONGBAI SUN are with the National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083, China. RONG ZHU is with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, China. LINGZHI YANG is with the School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China. Contact e-mail: yanglingzhi@ csu.edu.cn Manuscript submitted July 12, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B

The schematic of coherent jet experiment apparatus is shown in Figure 1. In this experiment, the supersonic jets with the shrouding gas under different parameter conditions are generated by Laval nozzle. The specific experiment conditions will be introduced later