Cool-burning Flames in ISS, leads to better engine /fuel development

A team of international researchers has discovered a new type of cool burning flames that could lead to cleaner, more efficient engines for cars.

The discovery was made during a series of experiments on the International Space Station by a team led by Forman Williams, a professor of mechanical and aerospace engineering at the University of California, San Diego.

Researchers detailed their findings recently in the journal Microgravity Science and Technology.

"We observed something that we didn't think could exist," Williams said.

A better understanding of the cool flames' chemistry could help improve internal combustion engines in cars, for example by developing homogenous-charge compression ignition.

This technology is not currently available in cars but it could potentially lead to engines that burn fuel at cooler temperatures, emitting fewer pollutants such as soot and nitric oxide and nitrogen dioxide, also known as NOx, while still being efficient.

During the experiments, researchers ignited large droplets of heptane fuel. At first, it looked like the flames had extinguished themselves, just as they would have on earth but sensors showed that the heptane was still burning, although the resulting cool flames were invisible to the naked eye.

This is a picture of the FLEX experiment set up on the International Space Station. 

Credit: NASA

The cool flames occurred in a wide range of environments, including air similar to the earth's atmosphere and atmospheres diluted with nitrogen, carbon dioxide and helium.

The resulting combustion reaction creates toxic products, such as carbon monoxide and formaldehyde, which in turn burn off.

Researchers believe that the cool flames are the result of elementary chemical reactions that do not have the time to develop around burning fuel droplets on earth, where they can only exist for a very short period of time.

The difference between earth and the space station is buoyancy. When droplets of fuel burn on earth, buoyancy limits the amount of time gases can hang around in the high temperature zone around the droplets.

So there isn't enough time for the droplets' chemistry to support the cool flames. But in micro-gravity, there is no buoyancy, so there is enough time for the gases to stay around the droplets and for that chemistry to develop.

The challenge for future applications is to get the right mix of fuels to generate this cool flame combustion here on earth.

To investigate this question, NASA is planning a new series of experiments tentatively called COOL FLAME INVESTIGATION, starting next winter and continuing for about a year.

Researchers emphasized that the research is only possible on the ISS, where scientists have access to a microgravity environment that provides a sufficient amount of test time for cool flames to occur.

All the experiments take place in the Multiuser Droplet Combustion Apparatus that can generate and ignite droplets from different fuels in different atmospheric conditions.

The chamber is crammed with sensors and equipped with video cameras that record experiments.

The chamber is inside an experimental facility called the Combustion Integrated Rack, which is roughly the size of a 5.5-foot bookcase and weighs close to 560 lbs and which records the data and transmits it to ground.

The Combustion Integrated Rack is located in the Destiny module of the ISS.

"Things can happen out there that can't happen here," Williams said.

NASA engineers crush fuel tank to build better rockets

NASA's Mark Hilburger prepares to buckle an aluminum-lithium cylinder about the size of fuel tank barrels for the largest rockets ever built. 

The black and white dots on the upper portion of the tank helped 20 high-speed cameras record minute changes in the tank as almost a million pounds of force pressed down upon the tank in a test at NASA's Marshall Space Flight Center. 

Credit: NASA/Fred Deaton

NASA completed a series of high-tech can-crushing tests last week as an enormous fuel tank crumbled under the pressure of almost a million pounds of force, all in the name of building lighter, more affordable rockets.

During the testing for the Shell Buckling Knockdown Factor Project, which began Dec. 9 at NASA's Marshall Space Flight Center in Huntsville, Ala., force and pressure were increasingly applied to the top of an empty but pressurized rocket fuel tank to evaluate its structural integrity.

The resulting data will help engineers design, build and test the gigantic fuel tanks for the Space Launch System (SLS) rocket NASA is developing for deep space missions.

"These full-scale tests along with our computer models and subscale tests will help NASA and industry design lighter, more affordable launch vehicles," said Mark Hilburger, senior research engineer in the Structural Mechanics and Concepts Branch at NASA's Langley Research Center in Hampton, Va.

Hilburger is conducting the tests for the NASA Engineering and Safety Center. "We were looking at real-time data from 20 cameras and more than 800 sensors during the final test."

The aluminum-lithium tank was made from unused space shuttle tank hardware and decked out in 70,000 black and white polka dots that helped high-speed cameras focus on any buckles, rips or strains.

"When it buckled it was quite dramatic," Hilburger said. "We heard the bang, almost like the sound of thunder and could see the large buckles in the test article."

Engineers are updating design guidelines that have the potential to reduce launch vehicle weight by 20 percent.

Lighter rockets can carry more equipment into space or travel farther away from Earth for exploration missions to asteroids, Mars or other distant locations.



"In addition to providing data for the Space Launch System design team, these tests are preparing us for upcoming full-scale tests," said Matt Cash, Marshall's lead test engineer for the shell buckling efforts and the SLS forward skirt and liquid oxygen tank structural testing.

"Performing structural tests on hardware that is the same size as SLS hardware is providing tremendous benefit for our future development work for the rocket."

The testing was conducted at Marshall's load test annex, part of the Structural and Dynamics Engineering Test Laboratory previously used to test large structures for the Saturn V rocket, space shuttle and International Space Station.

NASA's Space Launch System will provide an entirely new capability for human exploration beyond Earth orbit.

Designed to be flexible for crew or cargo missions, the SLS will be safe, affordable and sustainable to continue America's journey of discovery from the unique vantage point of space.

SLS will carry the Orion spacecraft's crew to deep space destinations including an asteroid and eventually Mars.

Developing a better motor for the Mars Rover

Elias Brassitos, a doctoral candidate in Distinguished Professor Dinos Mavroidis' Biomedical Mechatronics Laboratory, is developing a rotary robotic actuator that produces more power in a lighter package for a manipulator arm on NASA's Mars Rover. 

Credit: Brooks Canaday

In the world of robotics, identifying actuators that are strong and compact is probably one of the most important open technological problems yet to be resolved.

More often than not, the mechanical elements that translate data into doing are big, rough, and generally unfriendly for use in everyday robotics, said Dinos Mavroidis, Distinguished Professor of Mechanical and Industrial Engineering at Northeastern University.

In the mid-2000s, Mavroidis' lab set out to develop a new kind of actuator—small enough to sit inside the joints of prosthetic limbs, but powerful enough for everyday tasks such as lifting and walking.

Backed by two new grants—one from the National Science Foundation, the other from the National Aeronautics and Space Administration—Mavroidis' team will work to tailor the technology for use in advanced space applications as well as everyday household robots.

The gear bearing drive, or GBD, as the team's unique actuator is called, consists of a motor embedded directly inside the gear transmission, allowing for cheaper, lighter, and stronger functioning. The GBD is a compact mechanism with two key abilities.

It operates as an actuator providing torque and as a joint providing support. Back in 2006, Mavroidis and then graduate student Brian Weinberg developed the idea in collaboration with John Vranish, a NASA Goddard Space Flight Center engineer.

Elias Brassitos, a doctoral candidate in Mavroidis' lab, will use funding from a Space Technology Research Fellowship to develop the GBD for use on the Mars Rover.

"For space applications, everything needs to be lighter and stronger," said Brassitos, who noted that the device would replace the entire joint assembly for the rover's manipulator, the arm that extends outside the vehicle to collect rock samples and other things

"Mobile Robotics, particularly the use of rovers as part of a wider NASA exploration strategy, puts pressures on actuation technology," said Brett Kennedy, supervisor of the Robotic Vehicles and Manipulators Group at the Jet Propulsion Laboratory in Pasadena, Calif.

"We are always looking for ways to pack more torque, more power, and more functions into smaller packages," added Kennedy, who has high hopes that the GBD will help them do just that.

First, Brassitos must design various GBD architectures, each of which might be good for different applications. He'll design and build a prototype at Northeastern, and then assemble and test the device at the JPL.

While Brassitos works to develop the GBD for space, another graduate student will work to "commercialize it for earth."

In collaboration with the startup company Foodinie, which aims to make robots for the modern household kitchen, doctoral candidate Andy Kong and Mavroidis are developing an off-the-shelf version of the gear bearing drive that inventors can use for a variety of applications.

In some cases, the team will develop it for specialized needs as in the case of the Mars rover.

"There is a possibility for the GBD to be a source for innovation in the area of compact actuators for robotic systems," Mavroidis said.

Someone's Breath on Your Neck Makes you Hear Better

DEPENDING on whose it is, breath on your neck may or may not feel good. Either way, now it seems that it can help you understand what someone is saying. The discovery could lead to hearing aids that emit puffs of air.

We know that what we see affects what we hear. For example, if we hear "ba" while watching a person saying "ga" we think we've heard "da". Bryan Gick and colleagues at the University of British Columbia in Vancouver, Canada, wondered whether tactile sensations affect hearing too.

In speech, the "aspirated" syllables "pa" and "ta" are accompanied by a puff of exhaled air, whereas "ba" and "da" are not. Such puffs aren't always detected when someone is speaking, but Gick's team reasoned that the brain might learn to use puffs to modify its perception of certain sounds.

They had 66 volunteers listen to a male voice saying all four syllables against background noise that made it hard to distinguish them. At the same time as some of the syllables, they delivered a puff of air to the hand or neck.

Although many volunteers could not consciously feel the puffs, they were still more successful at correctly identifying "pa" and "ta" when these sounds were accompanied by air puffs. In contrast, air puffs made it less likely that they would correctly identify "ba" and "da" and more likely that they would mistake these for sounds for "pa" and "ta" (Nature, DOI: 10.1038/nature08572).