• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.273-281
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• 2001

Feasibility study of gas-lubricated bearing in micro gas turbine was performed. Based on Reynolds equation, finite difference method with coupled boundary was developed to analyze bearing characteristics, such as load-carrying capacity, mass flow rates and stiffness. By the bearing force and mass flow rates analysis with the variation of supply pressure, bearing clearance and capillary radius, acceptable range of design parameters were suggested in terms of load capacity and stiffness of bearings. Additionally, coupled boundary effect on pressure distribution was investigated and it is stated that coupling could reduce all excitation force due to narrow pressure distribution.

• Journal of Mechanical Science and Technology
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• 제17권6호
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• pp.906-913
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• 2003

Lean premixed combustion has been considered as one of the promising solutions for the reduction of NOx emissions from gas turbines. However, unstable combustion of lean premixed flow becomes a real challenge on the way to design a reliable, highly efficient dry low NOx gas turbine combustor. Contrary to a conventional diffusion type combustion system, characteristics of premixed combustion significantly depend on a premixing degree of combusting flow. Combustion behavior in terms of stability has been studied in a model gas turbine combustor burning natural gas and air. Incompleteness of premixing is identified as significant perturbation source for inducing unstable combustion. Application of a simple convection time lag theory can only predict instability modes but cannot determine whether instability occurs or not. Low frequency perturbations are observed at the onset of instability and believed to initiate the coupling between heat release rate and pressure fluctuations.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.561-565
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• 2009

초음속 충동형 터빈의 성능에 관해 시험적 방법으로 고찰하였다. 초음속 충동형 터빈은 고온, 고압의 연소가스로 구동되나, 연구원 내의 시험장치 한계 및 위험성으로 인해 고압의 공기를 이용하여 상사점에 대한 성능 시험을 수행하여 실매질 시험시의 터빈 성능을 예측하였다. 실제 연소가스로 구동되는 노즐 면적을 가지는 본품용 터빈 시험기를 공기로 구동시킬 경우 상사 조건을 정확히 맞추기는 어렵다. 그러므로 두 가지 상사 조건 시험을 통해 실제 설계점은 두 가지 상사점 사이에 존재하며 이 설계점은 공기의 물성치에 맞게 계산된 노즐 면적을 가지는 시험용 터빈 시험기를 통해 예측된 상사점과 비슷한 구간에 있음을 나타내었다.

• 한국유체기계학회 논문집
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• 제7권3호
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• pp.39-47
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• 2004

Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions lot a considerable amount of their lifetime. This study analyzes off-design performance characteristics of micro gas turbines and addresses the importance of the recuperation process doting the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration, and current vs advanced engines. Major finding is that maintaining high turbine exhaust temperature is crucial for efficient operation of micro gas turbines.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.80-87
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• 2003

Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions for a considerable amount of the time. This study aims at analyzing off-design performance characteristics of micro gas turbines and addressing the importance of the recuperator in the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration (fuel only control, variable speed operation, variable inlet guide vane control), and current vs advanced engines. Major finding is that maintaining turbine at high level is crucial in efficient operation of micro gas turbines.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.36-43
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• 2003

Operating performance of industrial gas turbines in combined cycle power plants depends upon atmospheric conditions. Compressor fouling caused by airborne particles in the atmosphere and their adhesions on compressor blades is one of critical phenomena related to the performance degradation of industrial gas turbines. Compressor fouling provokes increase of pressure loss in inlet duct, decrease of mass flow rate of intake air and decrease of compressor stage efficiency. In this study, impacts of compressor fouling on the performance of an industrial gas turbine operating at design point condition are investigated analytically. As results, it is found that the reduction of produced power with decreased mass flow rate of intake air caused by narrowed flow area by the adhesion of airborne particles on compressor blades is the most dominant impact on the gas turbine performance by the compressor fouling phenomena.

• Nuclear Engineering and Technology
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• 제39권1호
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• pp.9-20
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• 2007

Design study on the Gas Turbine High Temperature Reactor 300-Cogeneration (GTHTR300C) aiming at producing both electricity by a gas turbine and hydrogen by a thermochemical water splitting method (IS process method) has been conducted. It is expected to be one of the most attractive systems to provide hydrogen for fuel cell vehicles after 2030. The GTHTR300C employs a block type Very High Temperature Reactor (VHTR) with thermal power of 600MW and outlet coolant temperature of $950^{\circ}C$. The intermediate heat exchanger (IHX) and the gas turbine are arranged in series in the primary circuit. The IHX transfers the heat of 170MW to the secondary system used for hydrogen production. The balance of the reactor thermal power is used for electricity generation. The GTHTR300C is designed based on the existing technologies of the High Temperature Engineering Test Reactor (HTTR) and helium turbine power conversion and on the technologies whose development have been well under way for IS hydrogen production process so as to minimize cost and risk of deployment. This paper describes the original design features focusing on the plant layout and plant cycle of the GTHTR300C together with present development status of the GTHTR300, IHX, etc. Also, the advantage of the GTHTR300C is presented.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.211-218
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• 2000

Off-design experimental performance was investigated for a small centrifugal compressor, whose impeller diameter is about 125mm, used in an industrial gas turbine. Test rig was designed and manufactured with a radial inflow turbine and a combustor to supply driving power to the compressor. Static pressure was measured on the casing of the impeller, vaneless diffuser, vaned diffuser and volute. Total pressure was obtained using specially fabricated rakes at the vaned diffuser throat and exit. Circumferential nonuniformity was found, near surge, in the Impeller, vaned diffuser and volute region. Spanwise nonuniform flow from the impeller affected the total pressure defects in the vaned diffuser region. Static pressure distortion in the circumferential direction in the volute was found near surge, where the minimum occurred near 140 degree position.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.290-297
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• 2002

This paper presents analysis results for the effect of power control strategies on the part load performance of gas turbine based power generation systems utilizing exhaust heat of the gas turbine such as cumbined cycle power plants and regenerative gas turbines. For the combined cycle, part load efficiency variations were compared among different single shaft gas turbines representing various technology levels. Power control strategies considered were fuel only control and IGV control. It has been observed that gas turbines with higher design performances exhibit superior part load performances. Improvement of part load efficiency by adopting air flow modulation was analyzed and it is concluded that since the average combined cycle performance is affected by the range of IGV control as well as its temperature control principle, a control strategy appropriate for the load characteristics of the individual plant should be adopted. For the regenerative gas turbine, it is likewise concluded that maintaining exhaust temperature as high as possible by air flow rate modulation is required to increase part load efficiency.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.28-35
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• 2003

This paper presents analysis results for the effect of power control strategies on the part load performance of gas turbine based power generation systems utilizing exhaust heat of the gas turbine such as combined cycle power plants and regenerative gas turbines. For the combined cycle, part load efficiency variations were compared among different single shaft gas turbines representing various technology levels. Power control strategies considered were fuel only control and IGV control. It has been observed that gas turbines with higher design performances exhibit superior part load performances. Improvement of part load efficiency of the combined cycle by adopting air flow modulation was analyzed and it was concluded that since the average combined cycle performance is affected by the range of IGV control as well as its temperature control principle, a control strategy appropriate for the load characteristics of the individual plant should be adopted. For the regenerative gas turbine, it is likewise concluded that maintaining exhaust temperature as high as possible by air flow rate modulation is required to increase part load efficiency.