• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.413-418
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• 2012

A modified VIStA (Vortex Inertial Staged Air) burner has been developed and applied to a once-through type boiler. The secondary air is supplied through a swirler instead of nozzles, which stabilizes the flame and reduces carbon monoxide (CO) emissions. However, the modification increases the emission of nitrogen oxides (NOx). To balance emissions of the two pollutants, a divided flame was adopted. An air damper was installed to control the distribution of air to each combustion chamber, and three types of flame dividers were studied. The effects of the air-fuel ratio and combustion load on the NOx formation were investigated. The divided flame was found to reduce the NOx emission up to 25%, while keeping the CO to less than 10 ppm.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.734-741
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• 2004

Boundary layer ingestion in airframe-integrated scramjet engines causes engine stall (“engine un start” hereafter) and restricts engine performance. To improve the unstart characteristics in engines, boundary layer bleed and a two-staged injection of fuel were examined in Mach 4 and Mach 6 engine tests. A boundary layer bleed system consisting of a porous plate, an air coolers, a metering orifice and an ON/OFF valve, was designed for each of the engines. First, a method to determine bleed rate requirements was developed. Porous plates were designed to suck air out of the Mach 4 engine at a rate of 200 g/s and out of the Mach 6 engine at a rate of 30 g/s. Air coolers were then optimized based on the bleed airflow rates. The exhaust air temperature could be cooled below 600 K in the porous plates and the compact air coolers. The Mach 4 engine tests showed that a small bleed rate of 3% doubled the engine operating range and thrust. With the assistance of two-staged fuel injection of H2, the engine operating range was extended to Ф0.95 and the maximum thrust was tripled to 2560 N. The Mach 6 tests showed that a bleed of 30 g/s (0.6% of captured air in the engine) extended the start limit from Ф0.48 to Ф1 to deliver a maximum thrust of 2460 N.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.52-57
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• 2018

This paper presents the design and cold flow test results of oxidizer-rich preburner injectors for a 9 tonf-class staged combustion engine cycle. Three types of coaxial swirl injectors were designed, and 12 injectors were designed for each type. The diameters of the fuel tangential holes are identical. The diameters of the oxidizer tangential holes were varied to investigate the influence of combustion in the oxidizer-rich preburner according to the momentum ratio of the gas oxidizer generated from combustion in the injector chamber and liquid oxidizer through the cooling channel. It will be verified through a powerpack and combustion test using an oxidizer-rich preburner. In the cold flow test, the fuel flow rate and oxidizer tangential hole flow rate reached the target value based on the designed differential pressure.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.35-41
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• 2011

This work investigates the potential of in-cylinder thermal stratification and fuel stratification for extending the operating ranges in HCCI engines, and the coupling between thermal stratification and fuel stratification. Computational results areemployed. The computations were conducted using both a custom multi-zone version and the standard single-zone version of the Senkin application of the CHEMKINII kinetics rate code, and kinetic mechanism for di-methyl ether (DME). This study shows that the potential of thermal stratification and fuels stratification for extending the high-load operating limit by a staged combustion event with reduced pressure-rise rates is very large. It was also found that those stratification offers good potential to extend low-load limit by a same mechanism in high-load. However, a combination of thermal stratification and fuel stratification is not more effective than above stratification techniques for extending the operating ranges showing similar results of fuel stratification. Sufficient condition for combustion (enough temperature for) turns misfire in low-load limit to operate engines, which also leads to knock in high-load limit abruptly due to the too high temperature with high. DME shows a potential for maximizing effect of stratification to lower pressure-rise rate due to the characteristics of low-temperature heat release.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.125-131
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• 2018

Some propellants in a liquid rocket engine are burned in the pre-burner of a staged combustion cycle engine, resulting hot gas drives the turbine. The burned gas passing through the turbine is supplied to the combustor at high temperature and pressure. The form of the gas can be fuel rich or oxidizer rich dependent upon the mixture ratio or the engine scheme. When the cycle works at oxidizer-rich condition, the metal pipes composing the engine can be ignited or even exploded by an impact of very a small particle. In this study, we developed the powder combination and processes for an anti-oxidation coating through the analysis of various coating materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.453-459
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• 2004

An axially staged combustor equipped with an LPP combustion system and CMC liner walls has been investigated for stable combustion and low NOx emissions for the ESPR project. Several fuel injectors were designed and manufactured for the LPP burner, and single sector combustor tests were conducted to evaluate fundamental combustion characteristics such as emissions, instabilities, auto-ignition, and flash back at typical operating conditions from idle to Mn 2.2 cruise. The latest test results showed that the LPP burner had a good potential for the low NOx target. It was also found that the NOx emission level was greatly affected by a distortion in the air flow velocity field upstream of the LPP burner due to the diffuser and fuel feed arm. The CMC material was investigated to apply for the high temperature and low NOx combustor. Annular combustor liner walls were manufactured with the CMC material, and they have been tested at low pressure conditions to evaluate the soundness of the material and the mounting and seal system. This paper reports the latest research activities on the LPP combustion system and CMC liner walls for the ESPR project.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.5
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• pp.53-64
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• 2021

SpaceX has lowered rocket launch cost innovatively and put first stage reuse to the practical use with Falcon 9. Now the company is developing Starship system that is fully reusable with the heaviest payload in the world. So the system can lower the cost much more and fulfull more diverse mission. For the system the company have developed Raptor engine which is a full-flow staged combustion cycle one with methane fuel. And for the full reusability the company is manufacturing and testing the system prototypes with the barely used technologies such as stainless steel tank, belly flop and retropropulsion during descent. In this study the specification, missions and design features of the system are investigated. Also the development processes of Raptor engine and initial 13 Starship prototypes, which have been manufactured very rapidly, are presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.1-1
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• 2005

Japan Aerospace Exploration Agency(JAXA) has been conducting research and development of the Scramjet engines and their derivative combined cycle engines as hypersonic propulsion system for space access. Its history will be introduced first, and its recent advances, focusing on the engine performance progress, will follow. Finally, future plans for a flight test of scramjet and ground test of combined cycle engine will be introduced. Two types of test facilities for testing those hypersonic engines. namely, the 'Ramjet Engine Test Facility (RJTF)' and the 'High Enthalpy Shock Tunnel (HIEST)' were designed and fabricated during 1988 through 1996. These facilities can test engines under simulated flight Mach numbers up to 8 for the former, whereas beyond 8 for the latter, respectively. Several types of hydrogen-fueled scramjet engines have been designed, fabricated and tested under flight conditions of Mach 4, 6 and 8 in the RJTF since 1996. Initial test results showed that the thrust was insufficient because of occurrence of flow separation caused by combustion in the engines. These difficulty was later eliminated by boundary-layer bleeding and staged fuel injection. Their results were compared with theory to quantify achieved engine performances. The performances with regards to combustion, net thrust are discussed. We have reached the stage where positive net thrust can be attained for all the test coditions. Results of these engine tests will be discussed. We are also intensively attempting the improvement of thrust performance at high speed condition of Mach 8 to 15 in High Enthalpy Shock Tunnel (HIEST). Critical issues for this purposemay be air/fuel mixing enhancement, and temperature control of combustion gas to avoid thermal dissociation. To overcome these issues we developed the Hypermixier engine which applies stream-wise vortices for mixing enhancement, and the M12-engines which optimizes combustor entrance temperature. Moreover, we are going to conduct the flight experiment of the Hypermixer engine by utilizing flight test infrastructure (HyShot) provided by the University of Queensland in fall of 2005 for comparison with the HIEST result. The plan of the flight experiment is also presented.

• Journal of the Korean Society of Combustion
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• v.15 no.3
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• pp.48-56
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• 2010

Performances of power generation engine were investigated with syngas from RPF. A stoker type, multi-staged pyrolysis-gasification system, was employed for syngas generation and the syngas was refined with the sequential cleaning processes composed of a gas cooler, a bag filter and a wet scrubber. 20 kWe commercial syngas power generation engine was adopted to burn the cleaned syngas which is mainly composed of hydrogen, carbon monoxide, carbon dioxide and methane. The performance of the engine was tested with various syngas compositions and the results were compared to LNG case. Electric power output, exhaust gas temperature, and emission characteristics were measured, and the efficiency of engine generation was investigated as a function of load of power generation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.854-860
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• 2004

"Research and Development of Melt-Growth Composite (MGC) Ultra High Efficiency Gas Turbine System Technology" program has been started in JFY2001. The main objective of the program is to establish basic component technologies to apply MGC material to an efficient gas turbine system successfully. It is known that MGC material maintains its mechanical strength at room temperature up to about 2000 K, which is ideal for the high temperature gas turbine. The purposes of the present study are to develop the cooling structure of the gas turbine combustor liner where MGC material is applied as the heat shield panel, also to develop the low NOx combustion system for a 1970 K (1700 deg.C) class gas turbine combustor. To start with, basic heat transfer characteristics were investigated by one-dimensional calculation and heat transfer experiment for the cooling structure. Axially staged configuration and fuel preparation were investigated by CFD calculation and experiments for the low NOx combustor.