Friday, January 31, 2003

Candle Flames in Microgravity (CFM) Candle Flames in Microgravity (CFM) http://microgravity.grc.nasa.gov/combustion/cfm/cfm_index.htm   If you go to the Glenn Research Center Home Page for the study of combustion you will find more information on Candle Flames in Microgravity.  When the lights go out and you light up the candles, why do they flicker?  Would they flicker in space?  Would they flicker in low pressure?  Would they flicker under high pressure if you wanted to burn a hybid fuel using high pressure oxygen and a paraffin based fuel? - LRK - -----------------------------   Candles are often taken for granted, but they have been the object of scientific study for hundreds of years. Michael Faraday, the famous, 19th-century English scientist who discovered many principles of electricity, wrote that "there is no more open door by which you can enter into the study of natural philosophy [science] than by considering the phenomena of a candle." The goal of this project is to go through that open door by considering the process of combustion—as epitomized by candles—in environments with very little gravity (microgravity). The knowledge acquired from studying the physical and chemical properties of burning candles in space can help us use and control combustion more efficiently, and solve combustion-related problems in space and on earth. Specifically, scientists can apply what they learn to such areas as: Health and safety Pollution control Fuel efficiency Fire suppression The Candle Flames in Microgravity project is a collaborative effort by Drs. Howard Ross and Daniel Dietrich of the NASA Glenn Research Center, and Professor James T'ien of Case Western Reserve University. Their work is supported by NASA Headquarters, Microgravity Science and Applications Division. Snip Microgravity Combustion Science, January 2003 snip 8:37:11 PM    comment []

Floating Flame Balls Floating Flame Balls http://science.msfc.nasa.gov/headlines/y2002/21aug_flameballs.htm Here are some snips from an earlier article at Science @ NASA that gives more information about how fire burns in Microgravity. You see, science happens when you are curious, are asking questions and are able to take advantage of the unexpected.  Are you asking questions? - LRK - ------------------------------------ Flames do something odd in space: they form tiny almost-invisible balls that might reveal the secrets of combustion here on Earth. August 21, 2002: Paul Ronney wasn't looking for flame balls. They came as a complete surprise. It happened in 1984 when Ronney, a combustion researcher, was at the NASA Glenn Research Center's Microgravity Drop Tower in Ohio. He pressed a button and sent a can of burning hydrogen falling down a 90 ft. shaft. For 2.2 seconds it plummeted, freely falling and weightless, with a 16mm movie camera recording the action. Ronney knew that flames did strange things in low gravity--that's why he was doing the experiment--but he wasn't prepared for what he saw in the film room later. The flames had broken apart into tiny balls that moved around like UFOs. "I thought I had done something wrong," he recalled. Some of his colleagues didn't believe him when he described the experiment. Indeed, "it was ridiculous. No one had ever seen anything like it." snip Flames are hard to understand because they are complicated. In an ordinary candle flame, for example, thousands of chemical reactions take place. Hydrocarbon molecules from the wick are vaporized and cracked apart by heat. They combine with oxygen to produce light, heat, carbon dioxide and water. Some of the hydrocarbon fragments form ring-shaped molecules called polycyclic aromatic hydrocarbons and, eventually, soot. Soot particles can themselves burn or simply drift away as smoke. The familiar teardrop shape of the flame is an effect caused by gravity. Hot air rises and draws fresh cool air behind it. This is called buoyancy and is what makes the flame shoot up and flicker. Flame balls, on the other hand, are simple. The balls form in low gravity where turbulence and buoyancy have little effect. Oxygen and fuel combine in a narrow zone at the surface of the ball, not hither and yon throughout the flame. Once ignited and stabilized, their size remains constant. Unlike ordinary flames, which expand greedily when they need more fuel, flame balls let the oxygen and fuel come to them. Finally, the fact that flame balls are spherical reduces their dimension to one: the radius of the flame itself. snip 8:19:54 PM    comment []

A Flame Ball Named Kelly A Flame Ball Named Kelly http://science.nasa.gov/headlines/y2003/31jan_kelley.htm   Today on Science @ NASA an interesting write up about Flame Balls in Microgravity - LRK - Take a look at some snips below, go read the article with some what ifs in mind, like what if I was on the Moon in only 1/6 G, how would a flame spread?  What if I let Hydrogen and Oxygen leak out onto the vacuum of the Moon surface and strike a spark what kind of flame and where would the water vapor go?  What if I am at only 5 PSI in a Lunar Lander and I have a hydrogen and oxygen leak from a fuel cell and there is a spark - where does the flame go if I am in a landing pattern?  hmmmm - LRK - -----------------------------   January 31, 2003:  They're creatures of space: tiny flames that curl into balls and flit around like UFOs. They burn using almost no fuel at all, dim and often hard to see. Yet they have plenty of personality. snip   SOFBALL is a chamber about the size of an office trash can filled with combustible gases: "a little bit of hydrogen or methane (the fuel), some oxygen (the oxidant), and a lot of inert gas (e.g., helium or nitrogen) to dilute the mixture until it is barely flammable," says Ronney. The experiment rides in the shuttle's cargo bay inside a rack called the Combustion Module. Astronauts simply press a button to spark the mixture and voila ... flame balls. Their temperature, brightness, heat loss, and the composition of their gaseous byproducts are all monitored by built-in instruments. SOFBALL was built and tested at NASA's Glenn Research Center under the guidance of project scientist Karen Weiland and project manager Ann Over. snip Unlike flames on Earth, which have a tear drop shape caused by air rising in a gravitational field, flames in space break apart into spheres a few millimeters in diameter. A typical floating flame ball produces 1 to 2 watts of thermal power--much less than, say, a 50 watt birthday candle. "We created some flame balls on STS-107 that emitted only 0.5 watts--a record low," he says. Flame balls are "lean" burners; they don't need much fuel to keep going. Engineers would love to duplicate their efficiency in the engines of automobiles, "but first we have to understand how flame balls work," says Ronney. 8:08:01 PM    comment []