Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers Use Shock Tube for Insight Into Physics Early in Blasts

28.11.2012
Sandia’s one-of-a-kind multiphase shock tube began with a hallway conversation that led to what engineer Justin Wagner describes as the only shock tube in the world that can look at how shock waves interact with dense particle fields.

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, sholmes@sandia.gov, (505) 844-6362

Sue Holmes | Newswise Science News
Further information:
http://www.sandia.gov

More articles from Physics and Astronomy:

nachricht Two dimensional circuit with magnetic quasi-particles
22.01.2018 | Technische Universität Kaiserslautern

nachricht Meteoritic stardust unlocks timing of supernova dust formation
19.01.2018 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>