Hydrodynamic Study of a Submerged Entry Nozzle with Flow Modifiers
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THE main purpose of a submerged entry nozzle (SEN) is to distribute molten steel from a tundish to a mold; liquid metal occupies the mold volume and initiates the solidification process to obtain a semifinished product named slab.[1,2] The chemical composition of the steel is completed in the continuous casting furnace and the tundish. Inside the tundish, all non-metallic inclusions are removed from the liquid metal to reach the necessary quality of the steel.[3,4] In a SEN, the molten steel passes through a cylinder-shaped pipe, internal walls are usually made of alumina. The reaction between the steel and the nozzle refractory could cause clogging.[5] The gravitational force and the total metal weight from tundish send the fluid along the nozzle; there are two lateral exit ports in the SEN lower region. The liquid steel flow interacts with the bottom and the inner walls of the submerged nozzle, and develops two vortexes. Vortexes in the SEN lower region send the flow to the exit ports with a swirl, preponderant to one of the exit ports. Due to the vortexes’ evolution inside the SEN, the flow swifts and exits towards the mold through the other exit port. This phenomenon is repeated all the while.[6] The downward angle of the exit ports facilitates the outflow to the mold. The jet velocity magnitude, the frequency of switches in the exit ports, the SEN internal CESAR AUGUSTO REAL-RAMIREZ and JESUS GONZALEZTREJO are with the Systems Department, Universidad Autonoma Metropolitana, 02200, Mexico City, Mexico. Contact e-mail: [email protected] RAUL MIRANDA-TELLO is with the Electronics Department, Universidad Autonoma Metropolitana IGNACIO CARVAJAL-MARISCAL and FLORENCIO SANCHEZ-SILVA are with the Instituto Politecnico Nacional, ESIME, UPALM, 07738, Mexico City, Mexico. Manuscript submitted June 15, 2016. Article published online December 19, 2016. 1358—VOLUME 48B, APRIL 2017
geometry, the mold flow pattern, and the heat transfer affect the variations of the liquid jet swirl, and therefore, the free surface in the mold.[7–10] The mold is a rectangular-shaped vessel, copper-made container, opened in the upper and lower walls. Liquid steel is supplied from the tundish. The meniscus is the region where the solidification process starts and develops in the free surface at the mold’s upper edge; however, an average level of liquid metal should remain constant inside the mold to obtain a uniform solidification velocity in the shell. In this work, we propose to absorb the free surface fluctuations in the mold, by using external geometry of SEN because the fluctuations affect the steel quality directly. The volume between the free surface and the area above the nozzle exit ports are perpendicular and physically divided in four by a pair of flow modifiers attached to the external geometry of an original SEN, with the necessary thickness to obtain structural strength and maintain the operational conditions of a continuous casting process. Additionally, the flow modifiers were changed and two equidistant orifice grid designs were implemented in ord
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