Real-time identification of flow states in the DRESDYN precession experiment using distributed ultrasound sensors

• Applicants: Dr. Andre Giesecke; Professor Dr.-Ing. Christian Kupsch
• Subject Area: Fluid Mechanics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 532905681

The DRESDYN precession experiment is designed to improve our understanding of the dynamo effect. The core of the experiment is a cylinder filled with 6 tons of liquid sodium, which is rotated around two axes. The precession-driven liquid metal flow creates a magnetic field whose interaction with the flow will be analyzed. Currently, no measurement system exists to directly measure the flow structure and amplitude in this experiment. The main objective of this project is to enable a real-time identification of the global flow states and to determine the amplitude of the main large scale flow modes in the double rotating DRESDYN precession experiment. The measurement of these characteristic amplitudes and the identification of the flow transition provides an approximate idea of the geometrical structure of the flow, allows the derivation and confirmation of scaling laws that describe the efficiency of the flow forcing, and represents the essential prerequisite for an application to realistic planetary dynamo models when comparing with the flow response on the self-excited magnetic field in the saturated dynamo regime. Distributed, synchronized flow measurements using ultrasound will be performed to enable identification of the flow structures. The MSE Lab will develop the required ultrasonic sensors that will be attached to the experiment. The measurement data will be pre-processed locally on an FPGA to enable transmission via a wireless sensor network and thus real-time transmission of the measurement data from the experiment. At HZDR, the interface between experiment and data analysis is being developed. For this purpose, methods are applied for reconstructing the flow states from the local flow measurement data. On the one hand, the focus is on an efficient reconstruction to provide information about the flow state in real time. On the other hand, detailed reconstructions will be used to analyze the flow after the execution of the experiment to investigate the dynamic properties of the flow when a feedback effect of the self-excited magnetic field occurs. The project allows the analysis of the complex interaction of the flow of an electrically conducting fluid and the induced magnetic field. This enables an in-depth study of magnetohydrodynamic dynamos and thus contributes to a better understanding of dynamo action in the fluid interior of the Earth or similar planetary objects.

• DFG Programme: Research Grants