combustion chamber

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combustion chamber

[kəm′bəs·chən ‚chām·bər]
(aerospace engineering)
That part of the rocket engine in which the combustion of propellants takes place at high pressure. Also known as firing chamber.
Any chamber in which a fuel such as oil, coal, or kerosine is burned to provide heat.
(mechanical engineering)
The space at the head end of an internal combustion engine cylinder where most of the combustion takes place.

Combustion Chamber


a space for the combustion of gaseous, liquid, or solid fuel. Combustion chambers may be of the intermittent-operation type for two-cycle and four-cycle reciprocating internal-combustion engines or of the continuous-operation type for gas-turbine engines, turbojet engines, air-breathing engines, and liquid-propellant rocket engines.

In reciprocating internal-combustion engines the combustion chamber is usually formed by the interior surface of the cylinder head and the piston head. The combustion chamber of a gas-turbine engine is most often part of the engine; it may be annular, cannular, or tubular. A distinction is made between direct-flow and reverse-flow combustion chambers, depending on the direction of the flow of air and combustion products; reverse-flow combustion chambers are seldom used because of strong hydraulic resistance. The products of combustion pass from the combustion chamber into the gas turbine, but in some engines (augmented turbojet engines, liquid-propellant rocket engines) the products of combustion generate jet thrust as they accelerate in the nozzle behind the combustion chamber.

The basic requirements for all continuous-operation combustion chambers include stability of the combustion process, high thermal stress, maximum completeness of combustion, mini-mum heat loss, and reliable operation during the rated service life of the engine. The structural materials used in the manufacture of continuous-operation combustion chambers depend on the temperatures to be developed in them: for temperatures upto 500°C, chrome-nickel steels are used; for temperatures up to900°C, chrome-nickel steels with an admixture of titanium; and for temperatures above 950°C, special materials. Continuous-operation combustion chambers are major elements in aerospaceengines and specialized and transportation gas-turbine assemblies, which are widely used in power engineering, the chemical industry, railroad transportation, and river- and oceangoing vessels.

I. I. AKOPOV [11–-1]

Combustion chamber

The space at the head end of an internal combustion engine cylinder where most of the combustion takes place. See Combustion

In the spark-ignition engine, combustion is initiated in the mixture of fuel and air by an electrical discharge. The resulting reaction moves radially across the combustion space as a zone of active burning, known as the flame front. The velocity of the flame increases nearly in proportion to engine speed so that the distance the engine shaft turns during the burning process is not seriously affected by changes in speed. See Internal combustion engine, Spark plug

Occasionally a high burning rate, or too rapid change in burning rate, gives rise to unusual noise and vibration called engine roughness. Roughness may be reduced by using less squish or by shaping the combustion chamber to control the area of the flame front. A short burning time is helpful in eliminating knock because the last part of the charge is burned by the flame before it has time to ignite spontaneously.

In compression-ignition (diesel) engines, the fuel is injected late in the compression stroke into highly compressed air. Mixing must take place quickly, especially in smaller high-speed engines, if the fuel is to find oxygen and burn while the piston remains near top center. After a short delay, the injected fuel ignites from contact with the hot air in the cylinder. There is no flame front travel to limit the combustion rate.

If mixing of fuel and air is too thorough by the end of the delay period, high rates of pressure rise result, and the operation of the engine is rough and noisy. To avoid this condition, the auxiliary chamber is most compression-ignition engines operates at high temperature so that the fuel ignites soon after injection begins. This reduces the amount of fuel present and the degree of mixing at the time that ignition takes place. High rates of pressure rise can also be reduced by keeping most of the fuel separated from the chamber air until the end of the delay period. Rapid mixing must then take place to ensure efficient burning of the fuel while the piston is near top center. See Diesel engine

combustion chamber

i. The section of the gas turbine engine into which fuel is injected and burned. The combustion results in very high temperatures, which expands the air flowing through the combustion chamber and directs it onto the turbine at a uniform speed and temperature. A large amount of air passes around the walls of the combustion chamber to protect them. The three main types of layouts used for combustion systems are the multiple chamber, turbo-annular or cannular chamber, and annular chamber. Also known as burners and combustors. See can-type combustor.
ii. In a reciprocating engine, the space above the top dead center. See clearance volume.
References in periodicals archive ?
Figure 2 shows a 2D schematic of a cylindrical combustion chamber of radius R, although in general it could be of arbitrary geometry.
In such an engine, the ring walls of the combustion chamber contain a cold and hot side.
The scheme of the combustion chamber used in the research is given in Fig.
For example, a schematic of a hypothetical combustion chamber and exhaust is shown in Figure 4, and key dimensions are provided in Table 2.
In contrast, a three-pass combustion chamber is ideal for NOx reduction, as the gases exit the chamber at the rear, so that internal air recirculation is possible at a cooler temperature - resulting in a cooler flame and lower NOx levels.
A jet of hot decomposition products cut through the phenolic liner and ruptured the combustion chamber.
Experimental results allow: knowing the limits of variation temperature internal combustion engine cylinder head in order to study heat transfer in the body engine; a high temperature has adverse consequences on the functioning parts that separate the engine combustion chamber.
Spark-ignition knock is caused by the spontaneous ignition of gas ahead of the propagating flame front (the end gas) within the combustion chamber.
They coupled this innovation with another improvement, at the nozzle that injects diesel fuel into the combustion chamber.
Since the flow in the combustion chamber develops from interaction of the intake flow with the in-cylinder geometry, the goal of this work is to characterize the role of combustion chamber geometry on in-cylinder flow, thus the fuel-air mixing, combustion and pollutant formation processes.
The thermal kinetic process is very difficult to control and the one thing we have discovered is that while HCCI can give us a 15% fuel economy improvement over today's base line engine, but there are problems with combustion chamber deposits that develop during the combustion process.