• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.4
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• pp.81-88
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• 2013

It was designed and tested at the design point that an oxidizer rich preburner for a staged combustion liquid rocket engine propelled by kerosene and LOx. The oxidizer rich preburner was designed as some of LOx injected from the mixing head was burned with kerosene and the rest of LOx injected from injection holes in the regenerative cooling chamber was vaporized by combustion gas. The preburner is operated at OF ratio of 60 and combustion pressure of 20 MPa. The Preburner has a honey-comb type mixing head with simplex swirl injectors, a turbulence ring improving combustion stability and uniformity of product gas temperature distribution, and a nozzle simulating the duct. With the combustion test results at the design point, the oxidizer rich preburner showed high combustion stability and uniformity of product gas temperature distribution.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.636-641
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• 2010

A preburner for the staged combustion in the high performance liquid rocket engine is being developed and strength experiments and finite element analyses on specimens, which simulate the brazing joint of the preburner, were performed and the results were compared. One specimen simulate the joints near oxygen injectors of head by the funance brazing and two specimens the joints of the combustion chamber cooling channel by vacuum brazing. The experiments were burst ones with strain gauges.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.76-80
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• 2012

Uni-element preburners using a oxidizer-rich triplex injector have been designed and tested. During combustion tests 1L mode high-frequency instability of 1100 Hz and low-frequency instability of 100 Hz were observed. High-frequency instability has been suppressed by reducing chamber diameter and applying turbulent rings in combustion chamber. Recently, research to reduce low-frequency instability is in progress.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.63-69
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• 2014

The oxidizer-rich preburner's combustion tests were fulfilled in the development process of staged combustion cycle rocket engines. The exhaust plume from an oxidizer-rich preburner is relatively transparent because combustion takes place in oxidizer rich state. During hot fire tests a still and infrared images were captured to visualize the plume structure, temperature distribution and so on. In addition, the exhaust plume was numerically investigated to figure out the detailed characteristics. The combustion was not considered for the numerical modeling, but the mixing of exhaust plume with circumstantial air was modeled by species transport model with several turbulence models. The inner structure of plume was configured out by the comparison of numerical results with experimental results, and the validity of applied numerical models was verified.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.869-872
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• 2011

Ignition tests of an oxidizer rich preburner for a staged combustion cycle liquid rocket engine were performed to evaluate combustion performance. Design operation conditions of the tested oxidizer rich preburner are about 60 of OF ratio and 20 MPa of combustion pressure. The entire kerosene and some LOx injected into the mixing head is burned in combustion chamber and the remaining LOx injected through center holes of combustion chamber is vaporized. Full flow ignition method with hypergolic fuel was used. Each propellant was supplied in two stages for soft ignition. Test results, low frequency oscillation was occurred in low flow rate conditions under 45% of design flow rate. Stable ignition in the course of design combustion pressure was able to induce by minimization of low flow rate ignition region to escape low frequency oscillation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.106-109
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• 2012

It was designed and tested ignition that an oxidizer rich preburner for a staged combustion cycle liquid rocket engine propelled by kerosene and LOx. Operation conditions of the preburner are about 60 of OF ratio and 20 MPa of combustion pressure. Ignition characteristics were compared by propellants flowrate. As the results, the higher propellants flowrate, the shorter the ignition delay time and the higher ignition stiffness. The ignition delay time was affected by incoming the oxidizer flowrate through the refrigerative cooling channels. The oxidizer flowrate from the cooling channels decreased by inflow of combustion gas during initial ignition. The oxidizer flowrate of the cooling channels increases, it is rapid recovery by cooling effect, eventually the ignition delay time decreases.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.2
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• pp.50-55
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• 2011

A preburner for the high performance, staged combustion cycle liquid rocket engine is being developed. For the structural design processes, strength experiments and finite element analyses on specimens simulating the brazing joints of the preburner, were performed and compared. Total two kinds of the specimen were manufactured for the tests. One simulated the joints between the oxygen injectors and the head junctioned by the conventional vacuum brazing. The another was made to test the brazing surfaces by vacuum compression between the combustion chamber cooling channel and the outer wall. During the burst experiments, it was observed that the fractures were occurred not at the brazed joining but in the middle of the face plate and the cooling wall. In addition, the analysis showed that the predicted fracture locations and the strains were well matched with the experiment results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.88-93
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• 2017

For the control of pre-burner combustion pressure, the open angle of TTR(Throttle for Thrust Regulation) valve was varied from $143^{\circ}$ to $185^{\circ}$ while testing of cold flow, ignition, combustion. The major performance variables of rocket engine and hydraulic performance of TTR valve regarding the open angle was verified. However the controllability of pre-burner combustion pressure was not verified due to the limitations of test. The comprehensive research will be done after supplementing these problems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.97-100
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• 2011

It is critical to set up the starting sequence of liquid rocket engines because not carefully arranged process can lead the engine damages. Thus, many efforts were made to prevent the hard start at the ignition. Hypergolic fuels are frequently used to ignite LRE and TEAL, one of the hypergolic fuel is also used for kerosene-LOx LRE ignition. However, since we are still lack of experiences igniting oxygen rich preburners of the staged combustion cycle engines, it would be helpful to estimate the TEAL ignition phenomena before the actual tests.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.614-615
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• 2010

The propellants distribution of an oxidizer rich preburner was predicted by a simplified physical approach. The Mixing head is composed of honeycomb array of 7 fuel injectors and 24 oxidizer injectors. The OF ratio of the mixing head is 15. As results, the OF ratio of the central area is about 9 and the OF ratio of the wall area is about 30.