Monday  |  Pine/Spruce  |  09:40 AM–10:00 AM

#17476, Modification of Jet Velocities in an Explosively Loaded Copper Disk with a Conical Defect

The classical formulation for a Richtmyer‐Meshkov instability (RMI) problem involves an interface of two fluids with a sufficient Atwood number, representing the difference in densities between the fluids. An impulsive acceleration, such as a shock wave, impacts the interface. After the impact, there is a misalignment of the density gradient and pressure gradient, leading to baroclinic vorticity at the interface. The amplitudes of the perturbations grow as “spikes” or “bubbles” as the vorticity elongates the fluid boundaries: in many cases, this growth is unbounded. The limiting case of this interface growth is observed when the heavier fluid is forced into a stream, or jet, propagating away from the original interface.
RMI has been postulated to be responsible for deflagration– detonation transitions in combustion systems like internal combustion engines. RMI causes problems in inertial confinement fusion, where the driving shock can produce turbulent spikes of fuel‐rich media that are displaced from the reaction due to the instability.
Traditional investigations of RMI occur either computationally or in shock tube experiments. Another class of the RMI problem is found in the hydrodynamic behavior of metal at an interface with air or vacuum. This is a commonly leveraged phenomenon in military and resource extraction, known as shaped charges. Shaped charges use a high‐explosive (HE) driver to develop a jet of fluidized metal, which then acts as a
projectile in, for example, breaching operations by warfighters or adding holes in wellbores in fracking operations.
Computational work has been undertaken at Lawrence Livermore National Laboratory (LLNL) investigating the development of a material jet under HE driven experiments with different interfaces and charge configuration. There is evidence that a flyer—in the form of a jet driven by HE—can achieve
similar pressures as HE charges alone but extends the duration of maximum pressure compared to the Chapman‐Jouguet state of the driving HE. These investigations show that RMI can be created by an initially perturbed interface and a planar shock, or, they can be created by a perturbed shock front.
This work was performed under the auspices of the U.S. Department of Energy (DOE) by Lawrence Livermore National Security, LLC under Contract No. DE‐AC52‐07NA27344. We gratefully acknowledge
the LLNL Lab Directed Research and Development Program for funding support of this research under Project No. 21‐SI‐006.

Finnegan Wilson   Colorado School of Mines
Grace Rabinowitz   Colorado School of Mines
Max Sevcik   Colorado School of Mines
Gabriel Bjerke   Colorado School of Mines
Kadyn Tucker   Colorado School of Mines
Dylan Kline   LLNL
Michael Hennessey   LLNL
Kyle Sullivan   LLNL
Jonathan Belof   LLNL
Veronica Eliasson   Colorado School of Mines