# FLAME HOLDER:
Table of Contents:
- What Is Flame Holder?
What Is Flame Holder?
A flame holder is a component of a jet engine designed to help maintain continual combustion. All continuous-combustion jet engines require a flame holder. A flame holder creates a low-speed eddy 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.
A Simple Diagram of Ramjet Operation
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 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.
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object.
Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is most visible behind large emergent rocks in swift-flowing rivers.