Submerged Nozzle Oval Cross-Section Turbulence Reduction
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Solution Overview
Problem
High flow rates and turbulence during primary solidification in continuous casting of steel lead to unsteady liquid levels and irregular casting marks, resulting in increased surface defects and grinding work.
Innovation Solution
The immersion nozzle features a horizontal distribution channel with an oval cross-section and a symmetrical spherical cap that merges into a straight, upward course at angles between 45° and 30°, reducing turbulence by dissipating flow energy, and includes a cylindrical or oval inner channel with a run-up length of 8 to 10 times the shaft diameter to calm the melt flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high flow rates are used during primary solidification, then productivity is improved, but turbulence increases causing unsteady liquid level and surface defects
Solution Approach 1:
The immersion nozzle design incorporates a specific geometric configuration with a rounded outlet edge and optimized channel dimensions that preliminarily conditions the melt flow before it enters the mold. This preliminary action reduces turbulence and stabilizes the liquid level at the meniscus, allowing high casting speeds to be maintained without generating surface defects.
Solution Approach 2:
The invention changes critical geometric parameters of the immersion nozzle, specifically the outlet edge radius (R1 = 0.5-2.0 mm) and channel dimensions, to optimize flow characteristics. These parameter changes reduce flow energy and turbulence while maintaining high productivity, resolving the contradiction between casting speed and surface quality.
2Device complexity
If conventional immersion nozzle designs are used, then device simplicity is maintained, but flow velocity uniformity and turbulence control are insufficient
Solution Approach 1:
The invention applies local quality by providing different geometric characteristics at different locations within the immersion nozzle. The outlet edge has a specific rounded radius (R1), the distribution channel has optimized dimensions, and the deflection angle is specifically controlled. These localized geometric modifications improve flow velocity uniformity and reduce turbulence without requiring complex overall redesign of the nozzle structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves a smoother meniscus and reduces surface defects, thereby minimizing grinding work by ensuring a more uniform flow velocity and reduced turbulence during solidification.
Implementation Method 1
The advantage is a partial destruction of the flow energy of the melt already in the submerged nozzle. As a result, less turbulence is generated in the melt, resulting in a smoother meniscus.
Implementation Method 2
The run-up length of the flow in the inner channel corresponds to approximately 8 to 10 times the outer diameter of the shaft. This also results in an advantageous overall length as a distance to the view between the continuous casting mold and tundish.
Data Source
Figure 1~3
AI summary
Disclosed is a submerged nozzle (1) for liquid metals, especially steel materials, in continuous casting devices, such as continuous slab casting machines. Said submerged nozzle (1) comprises a shaft (2) with an internal duct (3) that extends into a transversal duct (4) and is provided with two outlets (4a; 4b) for deviations (6) in opposite horizontal directions (6). In order to reduce turbulence and energy of flow in said submerged nozzle (1), a distribution duct (8) that has an oval cross section (9) forms a symmetrizing spherical cap (10) oriented towards the shaft axis (2a) opposite the orifice (5) when used for liquid, alloy steel (high-grade steel).