[109-509 Fuel Burner, Sectioned]

The propellant burners (or "injectors" both are used in the literature), provide the means of bringing the rocket propellants into intimate contact in a controlled and measured way, to react to produce the motor's thrust. They are carefully engineered to produce a high rate of propellant flow, together with a regular, fine atomised spray.

The propellant burner is shown sectioned above. As discussed elsewhere, the twelve burners are set into the burner plate in groups of three, corresponding to first, second and third stage thrust settings. This is because satisfactory operation of the burner would not be possible over a large range of propellant flows without an excessive maximum pressure. The installation of the 109-509 motor in the Komet required the pilot to have control over the thrust with variable power settings, so bringing in sets of burners to add to the thrust output reduced the range demanded from individual burners.

[109-509 Fuel Burner Cutaway Diagramme]

The body of the burner is turned from steel into a cylinder. At the inner end is cut a circular groove into which is shrunk and pressed a steel ring. This ring is shaped so that a small annular chamber remains at the bottom of the groove, with a narrow gap between the ring and the inner radius of the groove, next to the body of the burner.

From the diagramme reproduced here, you can see that when the burner is mounted, the C-Stoff delivered to the burner plate passes into a channel which is turned in the body of the cylinder. Four tangentially drilled holes, labelled "3", connect this channel with the annular chamber in the head of the burner.

C-Stoff, flowing through the burner plate, passes into the machined channel around the burner, through the tangential holes into the annular chamber. From here, it is injected into the combustion chamber, through the narrow annular gap, "4", in the form of a fine cylindrical spray.

Around the channel in the burner, is a drilled filter ring, shown to the left of the diagramme here. This was fitted with a fine mesh steel gauze. It was designed to remove particles in the C-Stoff. However, as particles of dirt small enough to make it through the main filter would pass through the burner without blocking it, it was proposed to dispense with this filter. When fitted, the mesh was prone to trapping dirt, and clogging the filter, so that over time, the burner became so badly blocked it had to be changed.

Considering now the passage of T-Stoff, this enters the end of the burner through an axially bored hole. A poppet valve, spring loaded into a conical seat on the face of the burner, "2", seals the axial boring, at the combustion chamber face, and prevents any C-Stoff from entering the T-Stoff chamber when the motor is idling.

The maximum travel of the poppet valve is set by a distance piece on the valve stem, with a locking ring fitted at the end of the valve stem.

Prior to being injected into the combustion chamber, the T-Stoff passes through four tangentially drilled holes in the valve sleeve near the head of the burner, "1". The diameter of these holes is a method of providing some control over flow calibration of the T-Stoff, in the same way as the tangential holes in the C-Stoff side of the burner.

[Sectioned Combustion Chamber]

Shown here in the sectioned motor from the University of Minneapolis, the burners in the combustion chamber are set in groups.

[Burner Installation] [Burner Water Spray Test]

Before installation in the motor, each burner is check calibrated with water to ensure that its flow characteristics are within the range of safe and efficient operating parameters. The illustration on the left, shows a burner plate with the burners fitted, on a test stand, prior to undergoing a water test.

The picture on the right shows the burner system under test, and illustrates the fluid spray pattern very well.

Web Master Shamus Reddin   [SR Logo]
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