What is Combustion Chamber?- Function, And Types

A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.

As the Piston compresses the fuel/air mix and makes contact with the Spark Plug, the mixture is combusted and pushed out of the Combustion Chamber in the form of energy. The Cylinder houses many of the important components of an Internal Combustion Engine including the Injector Nozzle, Piston, Spark Plug, Combustion Chamber, and others.

What is a Combustion Chamber?

A combustion chamber is the area inside an engine where the combustion of fuel takes place. Fuel is mixed with oxygen, and the mixture is ignited. The energy released is captured, in one way or another, and harnessed. The forces produced are then typically used to drive the engine and produce some form of useful motion.

In a common automobile, the internal combustion engine contains anywhere from four to eight combustion chambers. These are located inside the cylinders. Gasoline and oxygen are mixed inside the chamber, a spark plug ignites the mixture, and the expanding gases drive the piston and crankshaft. This produces a spinning motion in the axles which then drive the wheels.

However, combustion chambers aren’t just found inside automobiles. There are two very different types of combustion engines, each with different combustion chambers, that can be put to any number of uses. For a discussion of both types as well as their elements, see the sections below.

Functions of Combustion Chamber

  • It provides a confined space for the combustion of air and fuel mixture
  • It houses the inlet & outlet valve for the incoming and outgoing of mixture
  • It houses and guides the piston
  • It helps in proper combustion by proper geometry
  • It withstands against the high temperature of combustion
  • It prevents to spill out the exhaust of combustion
combustion chamber

Types of Combustion Chamber

There are three main types of combustion chambers in use for gas turbine engines.

  • Multiple chambers,
  • The tubo-annular chamber
  • The annular chamber.

1. Multiple Combustion Chamber

This type of combustion chamber is used on centrifugal compressor engines and the earlier types of axial flow compressor engines. It is a direct development of the early type of Whittle combustion chamber.

The major difference is that the Whittle chamber had a reverse flow as illustrated, as this created a considerable pressure loss, the straight-through multiple chambers were developed by Joseph Lucas Limited.

The chambers are disposed around the engine and compressor delivery air is directed by ducts to pass into the individual chambers. Each chamber has an inner flame tube around which there is an air casing. The air passes through the flame tube snout and also between the tube and the outer casing as already described.

2. Tubo-annular Combustion Chamber

The tubo-annular combustion chamber bridges the evolutionary gap between the multiple and annular types. A number of flame tubes are fitted inside a common air casing.

The airflow is similar to that already described. This arrangement combines the ease of overhaul and testing of the multiple systems with the compactness of the annular system.

3. Annular Combustion Chamber

This type of combustion chamber consists of a single flame tube, completely annular in form, which is contained in an inner and outer casing.

The airflow through the flame tube is similar to that already described, the chamber being open at the front to the compressor and at the rear to the turbine nozzles.

The main advantage of the annular chamber is that, for the same power output, the length of the chamber is only 75% of that of a tubo-annular system of the same diameter, resulting in considerable saving of weight and production cost. Another advantage is the elimination of combustion propagation problems from chamber to chamber.

In comparison with a tubo-annular combustion system, the wall area of a comparable annular chamber is much less; consequently, the amount of cooling air required to prevent the burning of the flame tube wall is less, by approximately 15%.

This reduction in cooling air raises the combustion efficiency to virtually eliminate unburned fuel and oxidizes the carbon monoxide to nontoxic carbon dioxide, thus reducing air pollution.