The machine is considered multiphase because it can study shock wave propagation through a mixture of gas and solid particles.
Shock tubes — machines that generate shock waves without an explosion — have been around for decades. What makes Sandia’s unique is its ability to study how densely clustered particles disperse during an explosion. That’s important because better understanding of the physics during the first tens of microseconds of a blast leads to better computer models of what happens in explosions.
“Not having this correct in those codes could have implications for predicting different explosives properties,” Wagner said.
Understanding how particles move and react in the early part of a blast will help Sandia respond to such national security challenges as improving explosives, mitigating blasts or assessing the vulnerability of personnel, weapons and structures.
The project started when Steve Beresh of Sandia’s aerosciences department and Sean Kearney of the Labs’ thermal and fluid experimental sciences asked a since-retired colleague what he’d like to measure that he hadn’t been able to. He started talking about some of the physics missing from the models used for predicting explosives, “and Sean and I looked at each other and said, ‘We think we could do that,’” Beresh said.
They came up with the idea of a multiphase shock tube that would enable researchers to study particle dispersal in dense gas-solid flows.
The machine was fired for the first time in April 2010. Experiments and diagnostics are complicated, so team members are still gathering data they eventually will incorporate into codes used at Sandia and elsewhere.
“It’s clear that we’ve learned some things that weren’t known before,” Beresh said. “Those physics are important to a code.”
The stainless steel and aluminum shock tube, about 22 feet long, is divided into a high-pressure or driver section that creates the shock wave and a low-pressure or driven section, with a diaphragm between the two. Pressure builds up in the cylindrical driver section and when it gets high enough, the diaphragm ruptures. Spherical particles loaded into a hopper above the low-pressure section flow into the shock tube before the diaphragm breaks, creating a dense particle curtain that’s hit by the shock wave.
The project, initially funded under Sandia’s Laboratory Directed Research and Development program, hired Wagner to oversee the machine’s design and building. “When we hired Justin we had an empty room and a blank sheet of paper. Now we have a shock tube that is different from what anybody else in the world has,” Beresh said.
Particles in an explosion start out tightly packed. As the explosive process continues, they disperse and quickly become widely spaced. But the physics of the densely packed particles at the start of the explosion are crucial to everything that comes later. They are not yet fully understood, and thus limit current models, Wagner and Beresh said.
“The important thing about the shock tube is it generates a planar shock wave,” Wagner said. “We study the interaction of the shock wave with a dense field of particles to understand the physics relevant to explosives processes.”
Sandia’s machine uses such diagnostics as high-speed pressure measurements, high-speed imaging and flash X-ray to measure gas and particle properties, and it’s adding laser-based diagnostics, team members said.
“We can get different things from the X-ray diagnostics, different things from the laser-based diagnostics, different things from temperature and pressure measurements, and by piecing all of that together we get a better view of the physics that are occurring in the shot,” Beresh said.
The machine’s unique diagnostic capabilities demonstrate Sandia’s ability to collaborate. The team particularly singled out the X-ray expertise offered by Enrico Quintana and Jerry Stoker’s group in the experimental mechanics/non-destructive evaluation & model validation organization. Elton Wright of geothermal research also made sizeable contributions.
The diagnostics required to get useful information from the machine are difficult and expensive, Wagner said. “There’s a reason why it hasn’t been done thoroughly in the past,” he said.
A lot of data for modeling comes from explosions, but it’s difficult to isolate what happens in each part of a blast, Kearney said. “Whereas if you do an experiment like this you can delve deeper into what is really happening,” he said. “But it’s just one piece of the puzzle and they’re all important.”
Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies and economic competitiveness.
Sandia news media contact: Sue Holmes, email@example.com, (505) 844-6362
Sue Holmes | Newswise Science News
First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester
Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy