What is flame ?where is it used ?
What is flame ?where is it used ?
A flame is the visible, gaseous part of a fire.
It is caused by a highly exothermic reaction taking place in a thin zone.Very hot flames are hot enough to have ionized gaseous components of sufficient density to be considered plasma. Examples of flame in a Sentence -
the flame of a candle
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We built a fire and roasted marshmallows over the flames.
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They tried to put out the fire, but the flames grew higher.
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The engine burst into flame.
Flames in microgravity[edit]
In zero-G, convection does not carry the hot combustion products away from the fuel source, resulting in a spherical flame front.
In the year 2000, experiments by NASA confirmed that gravity plays an indirect role in flame formation and composition.[13] The common distribution of a flame under normal gravity conditions depends on convection, as soot tends to rise to the top of a flame (such as in a candle in normal gravity conditions), making it yellow. In microgravity or zero gravity environment, such as in orbit, natural convection no longer occurs and the flame becomes spherical, with a tendency to become bluer and more efficient. There are several possible explanations for this difference, of which the most likely is the hypothesis that the temperature is sufficiently evenly distributed that soot is not formed and complete combustion occurs.[14] Experiments by NASA reveal that diffusion flames in microgravity allow more soot to be completely oxidized after they are produced than do diffusion flames on Earth, because of a series of mechanisms that behave differently in microgravity when compared to normal gravity conditions.[15] These discoveries have potential applications in applied science and industry, especially concerning fuel efficiency.
Thermonuclear flames
Flames do not need to be driven only by chemical energy release. In stars, subsonic burning fronts driven by burning light nuclei (like carbon or helium) to heavy nuclei (up to iron group) propagate as flames. This is important in some models of Type Ia supernovae. In thermonuclear flames, thermal conduction dominates over species diffusion, so the flame speed and thickness is determined by the thermonuclear energy release and thermal conductivity (often in the form of degenerate electrons).
| A flame is the visible, gaseous part of a fire. |
-
the flame of a candle
-
We built a fire and roasted marshmallows over the flames.
-
They tried to put out the fire, but the flames grew higher.
-
The engine burst into flame.
Flames in microgravity[edit]
In zero-G, convection does not carry the hot combustion products away from the fuel source, resulting in a spherical flame front.
In the year 2000, experiments by NASA confirmed that gravity plays an indirect role in flame formation and composition.[13] The common distribution of a flame under normal gravity conditions depends on convection, as soot tends to rise to the top of a flame (such as in a candle in normal gravity conditions), making it yellow. In microgravity or zero gravity environment, such as in orbit, natural convection no longer occurs and the flame becomes spherical, with a tendency to become bluer and more efficient. There are several possible explanations for this difference, of which the most likely is the hypothesis that the temperature is sufficiently evenly distributed that soot is not formed and complete combustion occurs.[14] Experiments by NASA reveal that diffusion flames in microgravity allow more soot to be completely oxidized after they are produced than do diffusion flames on Earth, because of a series of mechanisms that behave differently in microgravity when compared to normal gravity conditions.[15] These discoveries have potential applications in applied science and industry, especially concerning fuel efficiency.
Thermonuclear flames
Flames do not need to be driven only by chemical energy release. In stars, subsonic burning fronts driven by burning light nuclei (like carbon or helium) to heavy nuclei (up to iron group) propagate as flames. This is important in some models of Type Ia supernovae. In thermonuclear flames, thermal conduction dominates over species diffusion, so the flame speed and thickness is determined by the thermonuclear energy release and thermal conductivity (often in the form of degenerate electrons).
