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Flame Types & Dynamics

Presented by: Ahmadreza Aminian (Ph.D. Student of Mechanical Engineering)

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Flame, a Definition

Flame involves the Chemical Reaction between one chemical substance

called a Fuel, and another chemical which is an oxidizer (or oxidant).

The chemical reaction between the fuel and oxidant is called Combusti

it is accompanied by the release of heat and usually by the emission of

light in the visible region of the spectrum.

Heat Transfer Mechanism in Flame is RADIATION…. 

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Flame Types & Classification

Flame color depends on several factors.

In the hydrocarbon flames, the most important factor determinin

color is oxygen supply and the extent of fuel-oxygen pre-mixing,

which determines the rate of combustion and thus the temperatu

and reaction paths, thereby producing different color hues.

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Flame Types & Classification

1. Fuel-Rich, with no pre-

mixed oxygen; produces a

yellow, sooty, and diffusive

flame; this kind of flame,

called:

the SOOTY FLAME

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Flame Types & Classification

3. By increasing the oxygencontent in flame atmosphere,we get to the higher levels oftemperature, this kind offlame called:

The NEUTRAL FLAME

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Neutral Flamea Closer Look

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Flame Types & Classification

4. a lean fully oxygen premixed flame

produces no soot and the flame color is

produced by molecular radicals, especially

CH and C2. this kind of flame earns the

highest level of flame temperature andcalled:

The OXYDIZED FLAME

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Flame Temperature

Variation of flame temperature with

equivalence ratio φ: 

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Flame Temperature of Various Fuels

Fuel  Oxidizer  Pressure (atm)  Temperature (

Acetylene  Air  1  2600 Acetylene  Oxygen  1  3410 

Carbon monoxide  Air  1  2400 Carbon monoxide  Oxygen  1  3220 

Heptane  Air  1  2290 Heptane  Oxygen  1  3100 Hydrogen  Air  1  2400 Hydrogen  Oxygen  1  3080 Methane  Air  1  2210 Methane  Air  20  2270 Methane  Oxygen  1  3030 Methane  Oxygen  20  3460 

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Flame Dynamics

The flame velocity—also called the

burning velocity, normal combustion

velocity, or laminar flame speed—is

more precisely defined as the velocity

at which unburned gases move

through the combustion wave in the

direction normal to the wave surface

Mallard–Le Chatelier Graph is a

description of the temperature in a

laminar fl ame wave

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