Generation of isentropic compression by use of multi-layer composite flyer and its influence on system thermodynamics: A simulation study

18th APS-SCCM; 24th AIRAPT

Ray, Aditi^1

Theoretical Physics Division, Bhabha Atomic Research Centre, Mumbai

400085, India^1

关键词: Increased flexibility;    Isentropic compression;    Multi-layered composites;    Multilayer composite;    Optimization techniques;    Relaxing constraints;    System thermodynamics;    Thermodynamic aspects;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/500/15/152011/pdf
DOI  :  10.1088/1742-6596/500/15/152011

来源: IOP

【 摘 要 】

Recently the possibility of achieving quasi-isentropic compression using functionally graded materials, in both gas gun and explosive driven systems was explored by hydro-dynamic simulations. In the current paper, we show that multi-layered composite flyer with progressively increasing shock impedances, referred to as graded density impactor (GDI), has the potential to enable increased flexibility in suitably tailoring the applied-pressure profiles, further relaxing constraints on the thermodynamic path of compressed material. Present simulation study pertaining to constant velocity impact of GDI reveals that linear ramp pulses of different pressure rise times, with comparable peak values can be realized only by changing the layer thicknesses of a particular GDI. We report generation of three different slope ramp pulses by five layer GDI made of PMMA, Al, Ti, Cu and Ta with different set of thicknesses obtained by genetic algorithm based optimization technique. Generation of long duration (μs) isentropic pressures using discrete GDI is a significant step, since it is devoid of fabrication difficulties of ultra-thin lamellae of FGM. Signatures of isentropic compression of a thin Cu target under different slope ramp loadings are identified from basic thermodynamic aspects in terms of temperature rise and entropy production. It is shown that that extent of entropy increase is closely related to the slope of ramping pulse. Further, a physical model has been constructed to determine approximate time profile of pressure pulse generated by equal layer-width GDI.