Periodic Reporting for period 1 - DYNPRESS (Towards materials at extremes: from intense dynamic compression to expansion)
Berichtszeitraum: 2022-09-01 bis 2025-02-28
The project aims at developing robust, reliable and effective techniques for generation of extreme conditions. Positive high as well as negative pressures in liquids are to be produced with limited resources available in everyday research environment.
The project offers a unique integration of approaches and resources in high voltage engineering and plasma physics applications towards classical problems of compressible fluid mechanics. It investigates by experiment, computation and theory the major physical properties of imploding shock waves in liquids and offers approaches to enhance efficiency of the focal energy concentration. The project develops a novel method for generation of imploding rarefaction waves, a well controlled scenario that provides with exactly opposite range of extreme conditions, namely negative pressures in liquids. The approaches comprise a single generator facility that opens research on a broad spectrum of basic-to-applied subjects, promising a long-term investment towards studies of materials at extremes.
The facility is applied on a selected subject of mechanical treatment of cellulose fibers, aiming at enhancing the efficiency of fibres disintegration, homogenization and fibrillation processes by applying, both selectively and combined, compression and tension pulses on a broad range of intensities, from strong to extreme.
The project offers a unique integration of approaches and resources in high voltage engineering and plasma physics applications towards classical problems of compressible fluid mechanics. It investigates by experiment, computation and theory the major physical properties of imploding shock waves in liquids and offers approaches to enhance efficiency of the focal energy concentration. The project develops a novel method for generation of imploding rarefaction waves, a well controlled scenario that provides with exactly opposite range of extreme conditions, namely negative pressures in liquids. The approaches comprise a single generator facility that opens research on a broad spectrum of basic-to-applied subjects, promising a long-term investment towards studies of materials at extremes.
The facility is applied on a selected subject of mechanical treatment of cellulose fibers, aiming at enhancing the efficiency of fibres disintegration, homogenization and fibrillation processes by applying, both selectively and combined, compression and tension pulses on a broad range of intensities, from strong to extreme.
The project has made substantial progress in developing both experimental and numerical methodologies to generate extreme conditions in liquids. A dedicated research facility, the DynPress lab, was established, equipped with a pulsed power generator and advanced diagnostic systems. The facility enables controlled generation of underwater explosions producing shock waves that travel at speeds of up to of 3 km/s and corresponding pressures in the range of tens of GPa. In addition a special technique is being developed to create a rapid tension of liquids to generate the proposed negative pressure ranges. Recent, yet not final, results demonstrate the appearance of cavitation effects in the vicinity of the rarefaction wave implosion.
For data collection, advanced high-speed imaging (up to 10 million frames per second) and fiber-optic hydrophone sensors were integrated to measure pressure changes with high accuracy, ensuring that shock dynamics could be recorded and analyzed in unprecedented detail. On the computational front, an in-house magnetohydrodynamics (MHD) code was developed , incorporating SESAME tables to improve the thermodynamic accuracy of simulations for materials like copper and water. This code, validated against experimental data, offers insights into energy transfer processes and material behavior in such extreme conditions.
For data collection, advanced high-speed imaging (up to 10 million frames per second) and fiber-optic hydrophone sensors were integrated to measure pressure changes with high accuracy, ensuring that shock dynamics could be recorded and analyzed in unprecedented detail. On the computational front, an in-house magnetohydrodynamics (MHD) code was developed , incorporating SESAME tables to improve the thermodynamic accuracy of simulations for materials like copper and water. This code, validated against experimental data, offers insights into energy transfer processes and material behavior in such extreme conditions.
The project has already achieved several advances that push beyond the current state of the art in experimental and numerical studies of shock wave dynamics. These include (1) the combination of ISW and IRW generators, Schlieren high-speed imaging and pressure measurement represent a major technological advancement of the project. This setup enabled the team to capture unprecedentedly detailed footage of shock wave formation, propagation, and interaction, allowing for new insights into the behavior of explosive processes. This level of resolution has been crucial in validating the numerical simulations and providing high quality experimental data; and (2) the incorporation of SESAME tables into our in-house combination of MHD+HD codes has significantly elevated the accuracy of shock wave simulations. Unlike conventional models that rely on idealized assumptions, these provide experimentally derived thermodynamic data that reflect real-world material behavior. This enhancement has allowed for a more precise representation of phase changes and energy transfer processes during underwater explosions, significantly advancing the modeling capabilities.