• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1482-1494
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• 2022

Power conversion cycles (Subcritical Steam, Supercritical Steam, Open Air Brayton, Recuperated Air Brayton, Combined Cycle, Closed Brayton Supercritical CO₂ (sCO₂), and Stirling) are evaluated for land-based nuclear microreactors based on technical maturity, system efficiency, size, cost and maintainability, safety implications, and siting considerations. Based upon these criteria, Air Brayton systems were selected for further evaluation. A brief history of the development and applications of Brayton power systems is given, followed by a description of how these thermal-to-electrical energy conversion systems might be integrated with a nuclear microreactor. Modeling is performed for optimized cycles operating at 3 MW(e) with turbine inlet temperatures of 500 ℃, 650 ℃ and 850 ℃, corresponding to: a) sodium fast, b) molten salt or heat pipe, and c) helium or sodium thermal reactors, coupled with three types of Brayton power conversion units (PCUs): 1) simple open-cycle gas turbine, 2) recuperated open-cycle gas turbine, and 3) recuperated and intercooled open-cycle gas turbine. Aeroderivative turboshaft engines employing the simple Brayton cycle and two industrial gas turbine engines employing recuperated air Brayton cycles are also analyzed. These engines offer mature technology that can facilitate near-term deployment with a modest improvement in efficiency.

• 한국추진공학회지
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• 제12권4호
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• pp.63-77
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• 2008

본 논문에서는 가스터빈에서의 연소불안정 현상과 그 메커니즘에 대해 살펴보았다. 연소불안정 연구를 위한 접근 방법이 논의되었고 전 세계 연소불안정 관련 연구그룹들의 최신 연구동향이 소개되었다. 현재까지도 연소불안정현상은 기관의 성능, 내구성, 작동 등에 영향을 미치는 중요한 문제 중의 하나이다. 덧붙여 가스터빈기관에서 연소불안정 현상은 공기 또는 연료의 섭동과 열방출율 사이의 상호 중첩된 결과로 알려져 있으며, 이는 NOx 감소 전략과도 관련이 있다. 따라서 연소불안정 연구에 대한 현황을 이해하기 위하여 가스터빈에서의 연소불안정 현상에 대하여 정리하여 보았다.

• Advances in aircraft and spacecraft science
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• 제4권1호
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• Tribology and Lubricants
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• 제13권1호
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• pp.70-75
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• 1997

The lubrication characteristics of high-speed ball bearings at oil-starvation have been investigated empirically using the bearings employed in small industrial gas turbine engines. For the close structural simulation, experiments carried our with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be applied to the design and the development of gas turbine engines. Testing was done by simulating the oil-starvation conditions in engines, such as stopping the oil-supply to the bearing during normal operating, starting without oil-supply at atmospheric temperature, and accelerating with oil-supply at atmospheric temperature. From this study, the relative comparison of the frictional resistance and the resistance due to the bearing cavity oil was demonstrated visually, and the resistance due to the bearing cavity oil was dominant in the resistance of bearing at high speed.

• Advances in Energy Research
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• 제3권1호
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• pp.31-43
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• 2015

This paper compares the performance of JP-8(Jet Propellant) fuel and liquefied petroleum gas (LPG) and natural gas in the F110 GE100 jet engine. The cost of natural gas usage in gas turbine engines is lower than JP-8 and LPG. LPG cost is more than JP-8. LPG volume is bigger than JP-8 in the same flight conditions. Fuel tank should be cryogenic for using natural gas in the aircraft. Cost and weight of the cryogenic tanks are bigger. Cryogenic tanks decrease the move capability of the aircraft. The use of jet propellant (JP) is the best in available application for F110 GE 100 jet engine.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.559-564
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• 2001

Advanced gas turbine engines employ turbine entry temperatures so high that cooling of the turbine blades is essential. The coolant flow introduces losses which need to be minimized, and therefore it is important that the minimum amount of coolant is used. This work presents the result of the one-dimensional analysis and the effect of the boundary conditions on coolant flow rate in gas turbine blades.

• 설비공학논문집
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• 제13권9호
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• pp.888-894
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• 2001

Advanced gas turbine engines employ turbine entry temperatures so high that cooling of the turbine blades is essential. The coolant flow introduces losses which need to be minimized, and therefore it is important that the minimum amount of coolant should be used. This work presents the result of the one-dimensional analysis and the effect of the boundary conditions on coolant flow rate in gas turbine blades.

• 한국자동차공학회논문집
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• 제2권2호
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• pp.42-48
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• 1994

Turbocharging is one of the best methods to improve the performance of diesel engines, because of its merits,-power ratio, fuel consumption and exhaust emissions. Most of them in small and medium diesel engines have adopted the pulse turbocharging method with twin entry vaneless radial turbines to maximize the energy utility of exhaust gas. This method requires the high performance of turbine under unsteady flow, and also the matching between turbine and diesel engine is most important. However, it is difficult to match properly between them. Because the steady flow data are usually used for it. Accordingly, it is necessary to catch the characteristics of turbine performance correctly over the wide range of the operation conditions under unsteady flow. In this paper, the characteristics of turbine performance under unsteady flow are represented at varying conditions, such as inlet pressure amplitude, turbine speed and frequence.

• 대한기계학회논문집B
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• 제36권8호
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• pp.791-796
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• 2012

항공기용 소형 가스터빈엔진은 항공기의 주엔진 시동을 위한 압축공기 공급, 비상 전원 등을 위한 보조동력장치로 사용된다. 항공기가 모래와 먼지가 함유된 대기 조건에서 운용되는 경우, 보조동력장치와 엔진에 대기 중 모래와 먼지가 유입되며, 이러한 모래 먼지 유입은 가스터빈엔진의 마모, 성능 저하 등을 야기시킨다. 본 연구에서는 모래와 먼지가 소형 가스터빈엔진에 유입되는 경우에 대하여 그 영향성을 고찰하였다. 시험에서의 모래와 먼지 농도는 공기 단위 질량당 $4.4{\times}10^{-5}kg$ 이며, 이는 미 군사규격인 MIL-E-8593 에 제시된 조건과 동일하다. 모래 먼지 유입시험은 총 10 시간 동안 수행되었으며, 시험 전 후의 성능시험을 통해 성능 영향성을 고찰하였다. 또한, 임펠러, 터빈휠 등 주요 구성품에 대하여 분해검사를 수행하여 마모 특성에 대하여 고찰하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.133-134
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• 2013

Gas turbine technology has steadily advanced since its inception and continues to evolve. Development is active in producing both smaller gas turbines and more powerful and efficient engines. However, it is shown that our state-of-the-art technologies for gas turbine developments remain at a basic level by comparisons with advanced technology countries. This paper shows that development process and preliminary design tools for gas turbine combustor were introduced as a first results of source technology secure researches for the gas turbine combustors.