Exploring the Behavior of a Coherent Flow Field Produced by a Shrouding Laval Nozzle Structure

For achieving a better stirring effect, the coherent jet technology has been widely adopted in the metallurgy field; a key feature of this technology is the use of a combustion flame to protect the main oxygen jet. In this paper, a shrouding nozzle with a Laval nozzle structure using preheating technology is introduced. The effect of the shrouding gas flow rate on the behavior of the main oxygen jet is investigated at room and high ambient temperatures. A computational fluid dynamics model has been built to investigate the flow field of the coherent jet in simulation studies. In addition, an experimental study has been carried out to verify the results of the numerical simulation. Based on the results, the new method improves the shrouding gas velocity and forms a low-density zone, which makes its velocity potential core length 178% and 174% longer than that generated by the traditional method at room and high ambient temperature, respectively. However, the shrouding jet forms a shock wave at the exit of the Laval nozzle, which results in removing kinetic energy from the main oxygen jet. As a result, the axial velocity of the coherent jet is smaller than that of the conventional jet, and the velocity variation increases as the flow rate increases.