Flames in the ISS

Candle Flames in Microgravity

Microgravity experiments using drop towers and Space Shuttle Orbiters have provided scientists valuable insights on how things burn. In the typical experiment, a flammable material, such as a candle, is ignited by a hot wire. 

The picture illustrate a combustion experiment conducted at the NASA Lewis Research Center 132 Meter Drop Tower. These pictures of a candle Candle Flames in Microgravity flame. As the picture illustrate, the flame stabilized, and its shape appears to be constant throughout the remainder of the drop. Instead of the typical teardrop shape seen on Earth, the microgravity flames becomes spherical. On Earth, the flame is drawn into a tip by the rising hot gases. However, convection currents are greatly reduced in microgravity. Fresh oxygen is not being delivered to the candle by these currents. Instead, oxygen works it way slowly to the flame by the process of diffusion. Soon, the flame temperature begins to drop because the combustion is less vigorous. The lower temperature slows down the melting and vaporization of the candle wax. Candles onboard the first United States Microgravity Laboratory, launched in June 1992, burned from 45 seconds to about 1 minute before being extinguished because of the dropping temperature and reduction of wax vapor.

From: NASA

Combustion, Complex Fluids, and Fluid Physics Experiments on the ISS

Motil, Brian; Urban, David

(NASA Glenn Research Center; Cleveland, OH, United States)

Abstract

From the very first days of human spaceflight, NASA has been conducting experiments in space to understand the effect of weightlessness on physical and chemically reacting systems. NASA Glenn Research Center (GRC) in Cleveland, Ohio has been at the forefront of this research looking at both fundamental studies in microgravity as well as experiments targeted at reducing the risks to long duration human missions to the moon, Mars, and beyond. In the current International Space Station (ISS) era, we now have an orbiting laboratory that provides the highly desired condition of long-duration microgravity. This allows continuous and interactive research similar to Earth-based laboratories. Because of these capabilities, the ISS is an indispensible laboratory for low gravity research. NASA GRC has been actively involved in developing and operating facilities and experiments on the ISS since the beginning of a permanent human presence on November 2, 2000. As the lead Center both Combustion, Fluid Physics, and Acceleration Measurement GRC has led the successful implementation of an Acceleration Measurement systems, the Combustion Integrated Rack (CIR), the Fluids Integrated Rack (FIR) as well as the continued use of other facilities on the ISS. These facilities have supported combustion experiments in fundamental droplet combustion fire detection fire extinguishment soot phenomena flame liftoff and stability and material flammability. The fluids experiments have studied capillary flow magneto-rheological fluids colloidal systems extensional rheology pool and nucleate boiling phenomena. In this paper, we provide an overview of the experiments conducted on the ISS over the past 12 years. We also provide a look to the future development. Experiments presented in combustion include areas such as droplet combustion, gaseous diffusion flames, solid fuels, premixed flame studies, fire safety, and super critical oxidation processes. In fluid physics, experiments are discussed in multiphase flows, capillary phenomena, and heat pipes. Finally in complex fluids, experiments in rheology and soft condensed materials will be presented.

Read the paper here [pdf].

You can conduct a classroom activity:
1) Candle flame in microgravity;
2) Educator guide.

Discovery that hints at origin of phenomena like solar flares

An argon plasma jet forms a rapidly growing corkscrew, known as a kink instability. This instability causes an even faster-developing behavior called a Rayleigh-Taylor instability, in which ripples grow and tear the jet apart. This phenomenon, the Caltech researchers say, has never been seen before and could be important in understanding solar flares and in developing nuclear fusion as a future energy source. Credit: A. L. Moser and P. M. Bellan, Caltech

In the experiments, Moser fired jets of hydrogen, nitrogen, and argon plasmas at speeds of about 10 to 50 kilometers per second across a distance of more than 20 centimeters in a vacuum. [...]

The experiment requires 200 million watts of power to produce jets that are a scorching 20,000 degrees Kelvin and carry a current of 100,000 amps. To study the jets, Moser used cameras that can take a snapshot in less than a microsecond, or one millionth of a second.

As in all electrical currents, the flowing electrons in the plasma jet generate a magnetic field, which then exerts a force on the plasma. These electromagnetic interactions between the magnetic field and the plasma can cause the jet to writhe and form a rapidly expanding corkscrew. [...]

She found that—more often than not—the corkscrew shape that developed in her jets grew exponentially and extremely fast. The jets in the experiment formed 20-centimeter-long coils in just 20 to 25 microseconds. She also noticed tiny ripples that began appearing on the inner edge of the coil just before the jet broke—the moment when there was a magnetic reconnection.

font: PhysOrg (click to read entire article)

NSTX fusion project

"DOE's Princeton Plasma Physics Laboratory (PPPL) is getting an earlier-than-expected start on a $94 million, nearly three-year project as the next stage of its mission to chart an attractive course for the development of nuclear fusion as a clean, safe and abundant fuel for generating electricity.

The project will upgrade the National Spherical Torus Experiment (NSTX) facility at PPPL, over the next 30 months, with completion slated for 2014. The work will enhance the position of the NSTX as the world’s most powerful spherical torus – or tokamak – a device that controls the superheated and electrically charged gases called plasmas that create fusion power."

in PhysOrg

Fusion energy is when atomic nuclei in plasmas combine at extremely high temperatures and release a burst of energy. Such reactions happens in the stars. But sustaining fusion in the laboratory has proven quite difficult because plasmas that leak from the confinement can halt the reaction. Controlling the plasma is thus a basic goal of fusion research.

ITER aims to produce a sustained fusion reaction in 2020s that will put out ten more energy than is needed to create it.

The NSTX (website) upgrade could also help determine the path to a possible next-generation spherical torus that would produce a burning plasma to complement the output of ITER.