This article is intended for general familiarization with the combustion process. The focus will be on the diversity of the species. In particular, we will focus on laminar, turbulent, heterogeneous and other types of combustion. We’ll talk separately about the fire.
Introduction
Before you start talking about the main topic of the article, about the types of combustion, let's get acquainted with the definition of the term.
Combustion is a chemical-physical process; a complex phenomenon is the conversion of substances that are the initial participants in an exothermic reaction into a combustion product. It is accompanied by a relatively large and intense heat release. Chemical energy stored as a reserve and residing in the components of the starting mixtures can also be output and take the form of radiation of heat and / or light. The luminous zone is called the front or flame.
Chemical combustion reactions most often “move” according to a branched-chain type mechanism with constant progression of self-acceleration. The latter occurs due to the release of heat in the reaction. Unlike other types of oxidative and reduction reactions, combustion has a large thermal effect, and the activation energy potential leads to a large dependence between the reaction rate and temperature. To begin the course of this phenomenon, the presence of an initiator is necessary. Humanity uses the potential of this process and all its types. Long-burning boilers, rocket and automobile engines, various burners and much more became possible precisely thanks to the research and study of combustion.
Classification
Types of combustion are classified according to different characteristics. For example, determining the type of process depends on the speed at which the combustion mixture moves. This difference makes it possible to distinguish between slow (deflagration) and detonation types of combustion. Waves of the first type are able to propagate at subsonic speeds, and the chemical reaction is supported by heating the reagents that form the shock wave. Heating, in turn, is responsible for the movement of the wave from the source (its propagation). Slow combustion is laminar and turbulent. Detonation always occurs in turbulent form. The types of combustion of gases, solids and liquids may have some features of the process. However, this is not an important factor determining the conditions for their classification.
Flame
Types of combustion and combustion conditions cause many different types of the main object of this article. A person uses them depending on the field of activity, starting from everyday life and ending with the design of space rockets.
Flames are part of the combustion process. However, it is important to remember that against the background of a laminar or turbulent genius, decay, etc., it is, rather, a description of a certain section of fire. Flames denote the luminous zone formed during the genius. Combustion of natural gas can cause air temperature to reach two thousand Kelvin.
The flame generated by the combustion of carbon fuel is capable of interacting with electromagnetic fields. This indicates the presence of charged particles. In fact, it has been proved that a flame may possess the “behavior” of a weakly ionized plasma. The phenomenon responsible for the generation of ions is called chemoionization.
Laminar form of burning
Speaking about the types of combustion, we should mention the concept of laminar genius. It is observed in the case of a low flow rate of the mixture. In this way, the candle burns, and gas stoves work at low fuel consumption. However, the gas in this case is mixed with other substances, which causes a constant movement of the flame front relative to the initial mixtures with specific speed conditions, which, in turn, depends on the temperature, pressure, and also reaction reagents. The ignition conditions do not play a role here.
Turbulent combustion
Turbulent genius is “work” on a mixture that can be defined as turbulent. This reaction is the most difficult to study, and it is also very common in practical mechanisms and devices. To date, there is no complete theory of turbulent combustion, which could fully describe this process.
There are many problems associated with the study of turbulent combustion. For example, the mutual influence of combustion on turbulence and vice versa leads to the fact that the genius process can both intensify due to heat generation (above the norm) and decrease. The latter is caused by an increase in viscosity with increasing temperature.
Heterogeneous combustion
Another type of combustion of substances is a heterogeneous reaction. These processes are the opposite of homogeneous. Such combustion occurs in a heterogeneous system, that is, a system containing more than the 1st phase (gas and liquid are examples). Also included here are processes occurring under conditions of a phase separation boundary. Very often, heterogeneous combustion means a chemical reaction, during which its reagent (fuel) evaporates, and the process occurs in different gas phases. An example is the combustion of coal in air. Here, carbon is able to react with oxygen molecules and form carbon monoxide, which, in turn, can burn out in the gas phase and cause the creation of carbon dioxide. There are several types of heterogeneous combustion, which may differ in mechanism.
Special Views
Smoldering is a special form of slow combustion. It is maintained due to the released heat in the reaction of O2 molecules with a hot condensed substance. The reaction occurs on the surface of the reagent and accumulates in the condensation phase.
Solid-phase g-nium refers to processes occurring in powders of inorganic and organic nature. These phenomena are related to autowave and exothermic. They are not accompanied by a noticeable release of gases.
Combustion in porous media is characterized by the fact that the medium itself, such as a ceramic matrix, is heated due to the consumption of a certain part of the heat. In turn, the initial mixture is heated by the matrix. Here the product is recovered.
There is also flameless burning.
"Fire!"
Burning is often considered a fire.
Fire is a process that a person does not control. It is not a type of burning, but nevertheless, a fire causes a lot of material damage and is also extremely dangerous for the life of animals, including humans. During the discovery and study of fire and its properties, the problem of fire became relatively common in people's lives. Among the methods of struggle, the main to this day remain preventive measures and immediate protection. The last function is performed by the operational response units - fire services. There are many special sirens. You can call these services by dialing 101. In addition to the main number, since 2013, a call to the 112 line has also been added. Most often, water, sand, a fire extinguisher, tarpaulins and asbestos materials are used to fight fires.