What is Flame? In chapter combustion …

Flame is a region where combustion or burning of a gaseous substance takes place. Only the solid or liquids which form gases when heated burn with a flame. Some of the substances which burn by producing flames are LPG, biogas, candle wax, camphor, magnesium and mustard oil. Charcoal and coal does not burn by producing a flame. When fuels burn, the type of flame produced depends on the proportion of oxygen available. When the oxygen supply is insufficient, then the fuels burn incompletely and produce mainly a yellow flame and when the oxygen supply is sufficient, then the fuels burn completely and produce mainly a blue flame.   Structure of a Flame: There are three zones or parts of a flame – innermost, middle and outer zone. Innermost zone: The innermost zone of a flame is dark or black. It consists of hot, unburnt vapours of the combustible material (candle). It is the least hot part of the flame. Middle zone: The middle zone of a flame is yellow. It is bright and luminous. In it the fuel vapours burn partially because there is not enough air so it produces carbon particles which become white hot and emit light. This zone is the major part of a candle flame. Outer zone: It is non-luminous zone. It is the outer zone of a flame where complete combustion of the fuel takes place because there is plenty of air around it. It has the highest temperature in the flame.

A particular region in which combustion takes place is called flame

Flame is a region where combustion or burning of a gaseous substance takes place. Only the solid or liquids which form gases when heated burn with a flame. Some of the substances which burn by producing flames are LPG, biogas, candle wax, camphor, magnesium and mustard oil.

Charcoal and coal does not burn by producing a flame.

When fuels burn, the type of flame produced depends on the proportion of oxygen available. When the oxygen supply is insufficient, then the fuels burn incompletely and produce mainly a yellow flame and when the oxygen supply is sufficient, then the fuels burn completely and produce mainly a blue flame.

 

• Structure of a Flame:

There are three zones or parts of a flame – innermost, middle and outer zone.

1. Innermost zone: The innermost zone of a flame is dark or black. It consists of hot, unburnt vapours of the combustible material (candle). It is the least hot part of the flame.
2. Middle zone: The middle zone of a flame is yellow. It is bright and luminous. In it the fuel vapours burn partially because there is not enough air so it produces carbon particles which become white hot and emit light. This zone is the major part of a candle flame.
3. Outer zone: It is non-luminous zone. It is the outer zone of a flame where complete combustion of the fuel takes place because there is plenty of air around it. It has the highest temperature in the flame.