A flame holder is a
component
Circuit Component may refer to:
•Are devices that perform functions when they are connected in a circuit.
In engineering, science, and technology Generic systems
* System components, an entity with discrete structure, such as an assem ...
of a
jet engine
A jet engine is a type of reaction engine discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include Rocket engine, rocket, Pump-jet, water jet, and ...
designed to help maintain continual
combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...
. In a
scramjet
A scramjet (supersonic combustion ramjet) is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully ...
engine the residence time of the fuel is very low and complete penetration of the fuel into the flow will not occur. To avoid these conditions flame holders are used.
All continuous-combustion jet engines require a flame holder. A flame holder creates a low-speed
eddy
Eddie or Eddy may refer to:
Science and technology
*Eddy (fluid dynamics), the swirling of a fluid and the reverse current created when the fluid flows past an obstacle
* Eddie (text editor), a text editor originally for BeOS and now ported to Lin ...
in the engine to prevent the flame from being blown out. The design of the flame holder is an issue of balance between a stable eddy and
drag.
The simplest design, often used in amateur projects, is the can-type flame holder, which consists of a
can covered in small holes. Much more effective is the H-gutter flame holder, which is shaped like a letter H with a curve facing and opposing the flow of air. Even more effective, however, is the V-gutter flame holder, which is shaped like a V with the point in the direction facing the flow of air. Some studies have suggested that adding a small amount of
base bleed
Base bleed is a system used on some artillery shells to increase range, typically by about 20–35%. It expels gas into the low pressure area behind the shell to reduce base drag (it does not produce thrust).
Since base bleed extends the ran ...
to a V-gutter helps reduce drag without reducing effectiveness. The most effective of the flame holders are the step type flame holder and the strut type flame holder.
The first mathematical model of a flame holder was proposed in 1953.
[ See p. 552.]
References
Jet engines
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