Contactless Velocity Measurement in Continuous Casting Molds
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Solution Overview
Problem
Existing methods for determining velocity distributions in continuous casting molds are either invasive, provide incomplete data, or require complex setups, making it difficult to achieve precise, contactless measurements of liquid metal flow, especially in steel casting where turbulence and conductive walls complicate signal measurement.
Innovation Solution
A simplified contactless inductive method using a single primary magnetic field to induce an electric current density in the liquid metal, which generates a measurable magnetic field, allowing for the reconstruction of velocity components through the solution of a Poisson equation and regularization of the resulting linear system of equations, enabling two-dimensional velocity field determination in continuous casting molds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are installed in the mold to determine flow pattern, then flow velocity can be determined, but direct intervention in the mold is required and the temperature signal has large inertia making rapid response difficult
Solution Approach 1:
The patent replaces mechanical/physical contact-based temperature sensors with a contactless electromagnetic measurement system. By applying an external magnetic field and measuring the induced voltage signals from the conductive liquid metal, the system determines flow velocity without physical intervention in the mold, thus resolving the contradiction between measurement capability and device complexity.
2Measurement precision
If a non-contact flow measuring device using turbulence-induced magnetic signals is used, then contactless measurement is achieved, but the method requires knowing the flow structure beforehand and high-frequency signals are strongly attenuated by conductive walls
Solution Approach 1:
The patent changes the measurement parameter from high-frequency turbulence-induced signals to low-frequency velocity-induced signals. By measuring the voltage induced by the motion of conductive liquid metal through an external magnetic field (MHD effect), the system avoids the skin effect attenuation that plagues high-frequency measurements in conductive environments, thus resolving the contradiction between contactless measurement and signal attenuation.
3Ease of manufacture
If a simplified two-dimensional velocity field assumption is made, then measurement complexity and effort are reduced, but the accuracy of three-dimensional flow reconstruction may be affected
Solution Approach 1:
The patent applies partial action by focusing measurement and reconstruction efforts on the dominant two-dimensional velocity components (radial and azimuthal) while neglecting the minor axial component. This selective approach reduces measurement complexity while maintaining sufficient accuracy for the primary flow characteristics, resolving the contradiction between ease of manufacture and measurement precision.
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 method provides a straightforward, contactless, and accurate measurement of velocity distributions in continuous casting molds, reducing measurement complexity and effort by assuming a two-dimensional velocity field, thus improving the precision and reliability of flow pattern analysis.
Implementation Method 1
by applying an external magnetic field b0 (primary field) an electric current density j is induced in the liquid metal
Implementation Method 2
This flow-induced current density generates an additional magnetic field according to the Biot-Savart law
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
The present invention is used for the non-contact determination of velocity distributions of a liquid metal in a continuous casting die. A preferred field of application of the device is the velocity determination in the continuous casting of steel and aluminum, in particular during slab casting. The determination is carried out in that a primary magnetic field penetrates the liquid metal volume in the die, the magnetic fields induced by the movement of the fluid is measured, and based thereon the velocity is calculated by solving an inverse problem. The calculation employs the principle of least squares, wherein the mean square deviations of the magnetic fields induced by the assumed velocity from the measured values is used as the functional to be minimized. In the process, the Tikhonov regularization is used, wherein the mean square curvature of the velocity field or the mean square velocity is used as the regularization functional. Furthermore, the divergence freedom of the velocity field is ensured by utilizing an additional functional. The array comprises a coil system generating a magnetic field, a measuring and control unit for the fluxes in said coil system, by which the direction of the magnetic field in the fluid can be changed, a plurality of magnetic field sensors in the outer region of the fluid for determining the magnetic fields induced by the movement of the fluid, and means for signal forwarding, processing and representation.