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.
(engineering)
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 ?
Engines with divided combustion chambers tend to have greater thermal losses than non-divided counterparts on account of the higher surface area-to-volume ratio and high flow velocities through the connecting passages.
Internal combustion engines (ICEs) have a combustion chamber with a typical design, which is formed by the bottom of the piston and the head of the cylinder with an integral volume.
With clean delivery systems and combustion chamber, fuel combustion will be optimize and function similar as a new engine.
Sound reflected back from the combustion chamber and flue will produce a fluctuating mixture flow or equivalence ratio that will feed back onto the flame.
Each time the burner starts the combustion chamber is purged with fresh air as a safety precaution, thus cooling the boiler prior to ignition and exposing it to increased thermal shock.
Cavity Resonances in Engine Combustion Chambers and Some applications, J.
The experimental investigations were carried out on four different combustion chambers designed at different primary zone equivalence ratios of 0.
The compression and sealing degrees of the combustion chambers are corroborated with the wear of the sealing element.
The water injection is a method of cooling the combustion chambers by adding water or water-methanol to the fuel-air mixture.
When you run the engine at low idle, fuel and oil aren't completely burned in the combustion chambers.
An organic engine conditioner, MPG-CAP comes as a capsule you drop into your tank and works in diesel, petrol or bio-diesel engines, creating a micro-thin coating on the combustion chambers so the fuel burns more efficiently with reduced emissions.
The Premium Fuel System Cleaning Service dissolves varnish and carbon in injectors, valves and combustion chambers, improves fuel economy, reduces emissions and restores power.