Printer Friendly

A new direction for microgravity fires.

Flames in space sometimes burn into the wind in seeming violation of the laws of physics, report scientists who have studied fire on the space shuttle. The researchers and shuttle astronauts described their experiments last week at a microgravity conference at the National Academy of Sciences in Washington, D.C. The studies, conducted in February 1996, could improve fire safety aboard the planned international space station.

In one experiment, an astronaut lit the center of a strip of paper clamped inside a wind tunnel. As a slight breeze blew from the right side of the tunnel, the flame bent into the wind and crept toward the right. "It's almost completely opposite [what happens in] normal gravity," says Takashi Kashiwagi, a fire science researcher with the National Institute of Standards and Technology in Gaithersburg, Md.

Although the phenomenon may strike some people as counterintuitive, Kashiwagi says, it makes sense. In gravity, oxygen flows around the flame, and the airflow determines the direction of the flame's reach. In low gravity, the oxygen downstream becomes depleted, so the flame seeks the most abundant supply of oxygen-the influx of air.

Not all flames in microgravity burn backward, though. In an experiment by Kurt Sacksteder of NASA's Lewis Research Center in Cleveland, the flame traveled in the expected direction. "At first glance, it may seem that our observations disagree, but they don't," Sacksteder says.

In the first experiment, the flame had paper to burn both upstream and downstream. It headed upstream because that side had more oxygen. In the second experiment, the strip of paper was lit at the end closer to the source of the breeze, with all of the fuel downstream. These flames spread much more quickly than the ones heading upstream in the first experiment. Sacksteder's experiment also shows that in a slight breeze, materials are more flammable in space than on Earth.

Kashiwagi's research produced what he calls a "crazy, unexplained smoldering phenomenon." A smoldering fire on Earth spreads outward in expanding rings as the fire burns more fuel.

Not in microgravity. A smoldering fire in space sends out tendrils away from the fire source. Each tendril splits into two, and each new tendril divides as the fuel smolders.

Kashiwagi says smoldering fires in space could prove "extremely dangerous" because they are hard to detect and would fill the air with toxins. Another series of experiments tested how well NASA's smoke detectors work in space. The detectors effectively measured fumes from burning candles, paper, metal wires, and rubber coating, says David L. Urban of NASA's Lewis Research Center.
COPYRIGHT 1997 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1997, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:experiments on fires in space show the influence of microgravity
Author:Smaglik, Paul
Publication:Science News
Article Type:Brief Article
Date:Feb 22, 1997
Previous Article:Radio astronomy gets off the ground.
Next Article:A supernova turns 10: birthday of an explosion.

Related Articles
U.S. firm contracts for use of USSR Mir.
Tracking growth and flow in microgravity.
Campus control of crystal growth in space.
Dancing droplets: studying liquids in microgravity yields applications for Earth and space.
Space city.
Space-age metals: freed from gravity, materials reveal their mysteries.
Vibrating grains form floating clumps.
Why did the space shuttle burn up? (Columbia Disaster).
NIST experiment's data acquired before space shuttle tragedy. (General Developments).

Terms of use | Privacy policy | Copyright © 2020 Farlex, Inc. | Feedback | For webmasters