Fire is a natural reaction between fuel and oxygen, which results in the release of heat energy and the growth of a flame. The products of combustion are water and carbon dioxide. There is no smoke or other products of combustion. However, the fuel and oxygen must be in sufficient quantities to create a complete combustion, or ‘burning’. Hence, there must be enough oxygen available to provide the fuel and oxygen with the energy to ignite and spread the flame.
What causes a flame to be a certain color? Essentially, all carbon that is burned in a fuel source is oxidized, resulting in a color that is blue, green, or orange. However, some trace amounts of carbon are released into the flame as it burns. This is why there are a wide variety of colors associated with the color of flames. Let’s take a closer look at the different types of flames and how they affect a flame’s appearance.
Rate of spread
The forward rate of fire spread was studied using a semi-physical network model. This model used the 10 m open wind speed and forward distance in its mathematical equations. It was compared to real fire data, and the differences were assessed as mean absolute error, bias error, and standard deviation. The researchers conclude that the forward rate of fire spread is an important component of defining fire suppression strategies and public warnings. To determine this rate, the researchers investigated the possibility of a simple relationship between open wind speed and the forward spread rate of fire.
Chemical composition of fuels
Inflammable materials such as petrol, wood, coal, and natural gas can be ignited in fires. The composition of the fuel is what determines how quickly it ignites. Fuels containing carbon, hydrogen, and oxygen are called organic. Some also contain nitrogen. Inorganic fuels, on the other hand, contain no carbon and are known as combustible metals. These materials react with oxygen in different ways and are therefore combustible.
In California, fire season began early, with large wildfires burning with surprising vigor in May. These fires were fueled by unprecedented levels of fuel resulting from years of drought and fire exclusion. Today’s fuels for fire are a mixture of dead trees, logging slash, and snow-crushed brush, along with highly flammable undergrowth, including many non-native grasses that promote rapid ignition and rapid spread.
The drying of dead fuels with free water takes place in three stages, with different mechanisms prevailing in each step. The first step of the drying process is known as the constant-rate period, which is independent of the fuel’s actual moisture content and hygroscopicity. The rate of drying decreases when the total fuel surface is below the critical moisture content, or fiber saturation. The second step, the decreasing-rate period, occurs as a result of the drying process slowing down and the fuel’s saturated surface area becoming dry. In this step, the moisture content of the fuel decreases by gradually evaporating back into the atmosphere.
Incandescence is the emission of electromagnetic radiation at high temperatures. Nearly all substances glow at around 798 K. Below this temperature, the incandescence is too weak to be noticeable, but at higher temperatures, it becomes brighter and changes color from red to white or blue. During a fire, this radiation causes the burning materials to emit light. It is a natural phenomenon and occurs all around us. Fires and heat are the primary causes of incandescence.
Light produced by fire
Fire produces light by scattering incoming light beams. This happens because light beams are not direct interactions between themselves. They cannot absorb each other and never bounce off one another. In addition, they do not deflect each other. Light consists of quantum particles called photons. These bosons can overlap and carry energy. This energy is released as light when the objects burned lose electrons. This light reflects off the surface of objects, creating a shadow.