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Effect of nozzle swirl blade on flow pattern in runner during uphill teeming
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
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2006 (English)In: ISIJ International, ISSN 0915-1559, Vol. 46, no 11, 1645-1651 p.Article in journal (Refereed) Published
Abstract [en]

Recent research has found a swirling flow induced by a twist-tape swirl blade inserted in the submerged entry nozzle of both slab and billet continuous casting molds to be remarkably effective for controlling the fluid-flow pattern in mold filling. The objective of the work reported on in this paper was to investigate usage of the swirl blade in the filling of molds in uphill teeming. Both mathematical and physical modeling were employed. Resulting velocity predictions and measurements corresponding to different positions in the water model were compared. Specific focus was on manipulation of the flow pattern by the swirl blade and its affect on flow unevenness, i.e. tangential and axial velocities. Good agreement was observed between the calculated and experimental results. The study's findings strongly suggest that equipping the entry nozzle of the uphill-teeming mold with a swirl blade would be a highly effective means of reducing flow unevenness during filling.

Place, publisher, year, edition, pages
2006. Vol. 46, no 11, 1645-1651 p.
Keyword [en]
Casting, CFD, Fluid flow, LDA, Modeling, Nozzle, Swirling flow, Uphill teeming
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:kth:diva-6743DOI: 10.2355/isijinternational.46.1645ISI: 000242258800014Scopus ID: 2-s2.0-33846391274OAI: oai:DiVA.org:kth-6743DiVA: diva2:11540
Note
QC 20100909Available from: 2007-01-18 Created: 2007-01-18 Last updated: 2012-11-20Bibliographically approved
In thesis
1. Effect of swirling blade on flow pattern in nozzle for up-hill teeming
Open this publication in new window or tab >>Effect of swirling blade on flow pattern in nozzle for up-hill teeming
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The fluid flow in the mold during up-hill teeming is of great importance for the quality of the cast ingot and therefore the quality of the final steel products. At the early stage of the filling of an up-hill teeming mold, liquid steel enters, with high velocity, from the runner into the mold and the turbulence on the meniscus could lead to entrainment of mold flux. The entrained mold flux might subsequently end up as defects in the final product. It is therefore very important to get a mild and stable inlet flow in the entrance region of the mold. It has been acknowledged recently that swirling motion induced using a helix shaped swirl blade, in the submerged entry nozzle is remarkably effective to control the fluid flow pattern in both the slab and billet type continuous casting molds. This result in increased productivity and quality of the produced steel. Due to the result with continuous casting there is reason to investigate the swirling effect for up-hill teeming, a casting method with similar problem with turbulence.

With this thesis we will study the effect of swirling flow generated through a swirl blade inserted into the entry nozzle, as a new method of reducing the deformation of the rising surface and the unevenness of the flow during filling of the up-hill teeming mold. The swirling blade has two features: (1) to generate a swirling flow in the entrance nozzle and (2) to suppress the uneven flow, generated/developed after flowing through the elbow. The effect of the use of a helix shaped swirl blade was studied using both numerical calculations and physical modelling. Water modelling was used to assert the effect of the swirling blade on rectifying of tangential and axial velocities in the filling tube for the up-hill teeming and also to verify the results from the numerical calculations. The effect of swirl in combination with diverged nozzle was also investigated in a similar way, i. e. with water model trials and numerical calculations.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. x, 33 p.
Series
ISRN KTH/MSE--06/68--SE+APRMETU/AVH
Keyword
swirling flow, up-hill teeming, nozzle, casting, fluid flow, modelling, CFD, LDA.
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-4269 (URN)978-91-7178-521-3 (ISBN)
Presentation
2007-01-19, Sal B2, KTH, Brinellvägen 23, Stockholm, 11:00
Opponent
Supervisors
Note
QC 20101115Available from: 2007-01-18 Created: 2007-01-18 Last updated: 2010-11-15Bibliographically approved
2. A Study of the Initial Mould Filling during Up-hill Ingot Casting
Open this publication in new window or tab >>A Study of the Initial Mould Filling during Up-hill Ingot Casting
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The fluid flow in the mould during up-hill teeming is of great importance for the quality of the cast ingot and thereby the quality of the final steel products. At the early stage of the filling of an up-hill teeming mould, liquid steel flows with a high velocity from the runner into the mould. The resulting turbulence on the meniscus can lead to entrainment of mould flux. The entrained mould flux might subsequently end up as defects in the final product. It is therefore very important to get a less turbulent and more stable inlet flow in the entrance region of the mould, to minimize the interactions between the steel and the mould flux. It has been acknowledged recently that a swirling motion, induced using a helix shaped swirl blade in the submerged entry nozzle, is remarkably effective to control the fluid flow pattern in both the slab and billet type continuous casting moulds. The focus in this thesis is the effect of a swirling flow, generated through a helix shaped swirl blade inserted into the runner system of the up-hill casting system, as a new method of reducing the deformation of the rising surface and the unevenness of the flow during filling of the up-hill teeming mould. The study covers a theoretical part, including mathematical modelling and water modelling experiments. Moreover, a part with some novel plant trials to test the swirling technology at the steel plants of Ovako bar in Hofors and Scana steel in Björneborg. The swirl blade has two features: (1) to generate a swirling flow in the entrance nozzle and (2) to suppress the uneven flow developed after flowing through a bend. Water modelling was used to assert the effect of the swirl blade on rectifying of tangential and axial velocities in the filling tube for the up-hill teeming and also to verify the results from the numerical calculations. The effect of swirl in combination with a diverged nozzle was also investigated in a similar way, i. e. with water model trials and numerical calculations. The earlier studies, using water as a fluid, have shown that the placement of a swirl blade in the vertical part of the runner channel, at the entrance to the mould, will be beneficial for a calm initial filling of the ingot during casting. Later, the plant trials were carried out to test if it would be possible to place a ceramic swirl blade in the runner channel during filling of ingots and to investigate the effect of a widening of the entry nozzle. Because of constrains of the current design of the runner systems at the steel plants it was not possible to place the swirl blade at the entrance. Instead, the swirl blade was placed in the horizontal part of the runner system. The initial experiments with swirl blade in the runner showed that no production disturbances were found. More specifically, no problems with unusual refractory wear or cracks in the refractory were found. Also, the mould powder consumption was found to decrease when using the swirl blade in combination with an inlet with a 6° diverged nozzle. Thus, it was concluded that the use of swirl blade has a potential in the future to be used to influence the initial filling conditions in a positive way. In addition to the plant trials with swirl blade, separate trials of changing the inlet angle from 1.7° to 6° or 10° showed that the widened inlet area resulted in a decrease in mould powder consumption. However, the decrease was not to the same extent as for the case with swirl blade.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. x, 70 p.
Keyword
swirling flow, up-hill teeming, nozzle, casting, fluid flow, modelling, CFD, LDA, swirl, ingot casting, filling, red eye
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-105384 (URN)978-91-7501-561-3 (ISBN)
Public defence
2012-11-30, B3, Brinellvägen 23, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20121120

Available from: 2012-11-20 Created: 2012-11-20 Last updated: 2012-11-20Bibliographically approved

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