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

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