• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.591-596
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• 1995

In order to investigate the reduction of NO emissions, natural gas was fueled for two-stage combustion apparatus. NO and CO emissions were described by five variables: total air ratio, primary air ratio, secondary air injection position, secondary air injection velocity, and swirl ratio. It was mainly observed that, as the primary air ratios of 0 and 0.4 NO emission decreased with increasing the secondary air injection position and secondary air injection velocity. The effect of weak swirl on NO emission was found to be insignificant.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.161-166
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• 2001

An Experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.849-855
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• 2017

The development of a staged combustion cycle engine with higher perfomance is essential to provide higher transport capability of space launch vehicles. The combustor head of engine has a cone-shaped head and its manifold of combustor has a very complicated structure. The head and manifold have been manufactured by casting or machining methode. Metal 3D printing technologies are recently known as one of promising methods to improve manufacturing process for them because they are possible to over come limitations of the two methods. In this paper, a selective laser sintering method is used to make test materials and their physical properties are studying by changing its operation parameters to establish the better processing conditions. It is found that the 3D printing method is acceptable to manufacturing the head or manifold of combustor for staged combustion cycle engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.9 s.252
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• pp.842-849
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• 2006

An experimental study has been conducted to investigate the effects of a multi air-staged burner on NOx formation and heat transfer in a 15kW large-scale laboratory furnace adopted the reburning process. The reburn fuel as well as burnout air was injected from each nozzle attached at the wall of the cylindrical furnace. Fuel in both main burner and reburn nozzle was LPG (Liquefied Petroleum Gas). The paper reports the influences on NOx reduction of reburn fuel fraction in reburning zone. Temperature distribution inside the overall region as well as total heat flux at the wall of the furnace has been measured to examine the heat transfer characteristics due to the reburning process. For comparison, the reburning effects were examined for a combustor with two types of burner; a regular single staged burner and a multi-air staged burner. A gas analysis was also performed to evaluate an appropriate condition for NOx emission in a primary zone for the excess air ratio of 1.1. As a result, combustion efficiency expected to become more efficient due to the reduction of heat loss in burnout zone decrease when multi air-staged burner in furnace adopted reburning technology was used.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.5-8
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• 2010

The GCSC injectors studied in this paper are those applied to the combustion chamber of staged combustion engines. Liquid fuel is injected through tangential holes along the outer wall of the GCSC injector forming a swirling sheet and oxygen rich gas generated by a preburner enters axially through the center orifice of the injector to form a gaseous jet. The spray characteristics of GCSC injectors under ambient/high pressure conditions and the effect of recess on spray characteristics have been examined in this paper. These results are expected to be used as fundamental data to develop of a staged combustion engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.62-70
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• 2015

A liquid rocket engine system can cause rapid pressure and temperature variations during the startup period. Thus the startup analysis is required to reduce time and expense for successful development of liquid rocket engine through the startup prediction. In this study, a startup analysis simulator is developed for a staged combustion cycle engine powerpack. This simulator calculates propellant flow rates using pressure and flow rate balances. In addition, a rotational speed of turbopump is obtained as a function of time by mathematical modeling. A startup analysis result shows that the time to reach a steady-state and a rotational speed at the steady-state are 1.3 sec and 27,500 rpm, respectively. Moreover it can indicate proper startup sequences for stable operation.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.125-130
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• 2018

The technology development of a high performance upper stage engine for a GEO(GEostationary Orbit) KSLV(Korea Space Launch Vehicle) is undergoing in Korea Aerospace Research Institute. KSLV is composed of an open cycle engine with gas generator, which is for a low orbit launch vehicle. However the future GEO launch vehicle requires a high performance upper stage engine with a high specific impulse. The staged combustion cycle engine is necessary for this mission. In this paper, current progress and future plan for staged combustion cycle engine development is described.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.311-312
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• 2012

Homogeneous charge compression ignition combustion with multiple-injection strategy using dimethyl-ether was investigated in a single cylinder direct-injection compression-ignition engine. The combustion performance and exhaust emissions were tested by varying the post injection conditions. The experiments were carried out under low load and low speed conditions. By the late post injection near the top dead center, the combustion phase was retarded and lengthened, and the fuel conversion efficiencies improved without the drawbacks of exhaust emissions increment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.437-443
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• 2014

Engine is one of the most important parts in a rocket for completing its mission successfully. In this paper, we provide a methodology for estimating reliability and development cost of a liquid rocket engine newly developed. To estimate reliability, a baseline engine is selected considering factors whose effects on reliability are unquantifiable. Then reliability of a baseline engine is adjusted to reflect the effect of factors that can be modeled quantitatively. Using the previous Transcost engine cost expressed in terms of mass and the number of hot firing tests, the engine development cost is reexpressed in reliability and thrust requirements. Finally, a numerical example is given to illustrate the application of the methodology to a turbopump rocket engine using staged combustion cycle with LOX/LH2 propellant.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.106-112
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• 2012

Since air pollution problem by emissions from automotive vehicles has become social issues, lean-burn gasoline direct injection (GDI) engine is focused as an alternative to meet the requirement of reinforced emission regulation and improved fuel consumption. Spray-guided type DI combustion is promising technology, which characterized by the centrally mounted injector and closely positioned spark plug, since stable lean combustion can be realized even at ultra-lean mixture condition. In the present study, the effect of multi-ignition with developed charge coil on combustion and emission characteristics was investigated in optical accessible single cylinder engine. In order to fully understand the in-cylinder phenomena and the mechanisms of emission production, optical diagnostics, such as flame visualization was also carried out at frequently using operating condition. Multi-ignition is effective to improve fuel economy but increase NOx emission at flammability limit.