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Institute for Measurement Technology
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Acoustic and Vibratory Characterization of Liquid Steel Flows in Continuous Casters

Dipl.-Ing. Dr. Thomas Wiesner

Supervisory committee:

Univ.-Prof. Dipl.-Ing. Dr. Bernhard Zagar

Univ.-Prof. Dipl.-Ing. Dr. Alexander Sutor

Final exam:

January 18th, 2019

 

The first part investigates Laser Doppler Vibrometer (LDV) measurements and contacting vibration measurements on the exterior surface of the SEN for capturing the Acoustic Emissions (AE) of the steel and argon two phase flow within. Measurements on plant SENs during operation were performed. Signal despiking was necessary before the measurement data could be processed with conventional and
cyclostationary spectral signal analysis. The influence of possible correlations between disturbance signals and the stopper movement was investigated with a noise simulation of the LDV. The second part examines AEs generated by the bubble detachment from the stopper. Experiments with microphones and a custom acoustic membrane coupler were performed on a laboratory model.

Conventional and cyclostationary spectral features were found in part one. Figure 1
shows an example of a measurement result. Changes of the AEs with the gas flow rate could be observed in model experiments in part two.

Keywords: continuous casting, steel, cyclostationary signals, submerged entry nozzle, acoustic emissions, argon, laser doppler vibrometer, noise simulation, spikes, microphone

The circulation of the project work is restricted from January 10, 2019 for the period of 5 years.

Continuous Casting is currently the main technology for the solidification of liquid steel into various shapes. The high temperature of liquid steel and the harsh environmental conditions in a steel plant render measurements of casting process parameters and liquid steel flow parameters difficult.

This thesis was supported by the Austrian Center of Competence in Mechatronics project "Messtechnische Charakterisierung von Flüssigstahlströmungen" in cooperation with Voestalpine AG and Primetals Technologies Ltd. It focuses on characterizing the steel flow in the Submerged Entry Nozzle (SEN) with acoustic and vibratory measurements.

Figure 1: Example of the cyclic spectral coherence time evolution of the submerged entry nozzle vibration at three different cyclic frequencies.