• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2342-2344
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• 2000

Many years ago, most of thermal power plants built in this country were of subcritical pressure, of medium or small size, of constant pressure operation, of drum type steam generator. But, nowadays, almost all of them were of high efficiency, of supercritical pressure, of great capacity(about 500MW), of sliding pressure operation, of once through type steam generator. Presently built once through boiler introduces turbine bypass systems to variable pressure operation which eliminates unexpected materials in boiler tube during startup, minimizes fuel loss by short startup period, eventually improves total efficiency and power system stability

• 한국유체기계학회 논문집
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• 제17권3호
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• pp.46-51
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• 2014

In this study, a numerical analysis methodology is studied to predict thermal and flow characteristics of C3X vane with internal cooling. Effects of turbulence models, transition models and viscous work term on temperature and pressure distributions on the vane surface are investigated. These optional terms have few effects on the pressure distributions over the vane surface. However, they have great influence on prediction of the temperature distributions on the vane surface. The combination of k-${\omega}$ based SST turbulence model, ${\gamma}$ transition model and viscous work term are better than RSM turbulence model on prediction of the surface temperature. The average temperature difference between CFD results and experimental results is calculated 2 % at the pressure side and 1 % at the suction side. Furthermore computing time of this combination is half of the RSM turbulence model. When k-${\omega}$ based SST turbulence model and ${\gamma}$ transition model with viscous work term are applied, more accurate predictions of thermal and internal flow characteristics of high pressure turbine are expected.

• 한국소음진동공학회논문집
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• 제19권12호
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• pp.1281-1288
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• 2009

Variation of dynamic characteristics of a low pressure turbine blade with crack length is studied in this paper via both experiments and finite element model. Since most of the turbine blades used in domestic power plants are imported from abroad, it is necessary to understand their dynamic behavior in advance. When experimentally obtained natural frequencies and mode shapes are compared with those from FEM results, they are close to each other in their magnitude. Then, it is more feasible to use finite element model for analyzing the dynamic characteristics of a blade under various operation conditions (rotation speed, temperature, etc) as well as with a crack in the blade.

• 해양환경안전학회지
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• 제29권4호
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• pp.395-406
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• 2023

우리나라 열병합 발전소에서 운영되고 있는 최신 증기터빈의 출력과 효율 향상을 위한 첫 번째 기술적인 진보는 고온, 고압의 증기를 사용할 수 있는 소재 개발의 진척이라고 할 수 있다. 소재의 발전과 더불어 증기터빈의 내부효율 향상을 위한 설계적 노력의 결실로 높은 효율의 증기터빈이 제작되었다. 오랜 기간 운전 중인 증기터빈의 내부효율은 기계적 수명의 한계로 점차 손실이 발생하고 효율과 출력이 떨어지게 된다. 이러한 이유로 본 연구에서는 상용프로그램을 이용하여 열병합 발전소용 고압(HP)-중압(IP) 증기터빈의 증기유로 성능해석을 수행할 수 있는 모델을 개발하고 성능계산 방법을 제시하고자 한다. 증기터빈의 복잡한 성능계산방식으로 인해 증기터빈 실무자들에게 실질적으로 유용한 참고문헌이 될 수 있도록 주요 변수들을 제시하였다. 또한 증기터빈 성능계산에 필요한 열정산도 분석과 증기터빈 성능계산 결과의 적합성을 성능시험 결과와 비교 확인하였다.

• 전기학회논문지
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• 제59권1호
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• pp.152-159
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• 2010

This paper describes the actual application of a feedback control loop as a means for minimizing turbine impulse chamber pressure variation during the turbine steam valve tests at a 1,000 MW nuclear power plant. The chamber pressure control loop was implemented in the new digital control system which was installed as a replacement for the old analog type control system. There has been about 40MW of the generator output change during the steam valve tests, especially the high pressure governing valve tests, because the old control system had not the impulse chamber pressure control so the operators had to compensate steam flow drop manually. The process of each valve test consists of a closing process and an reopening process and the operators can make sure that the valves are in their sound conditions by checking the valves movement. The control algorithm described in this paper contributed to keep the change in megawatt only to 6MW during the steam valve tests. Thereby, the disturbance to reactor control was reduced, and the overall plant control system's stability was greatly improved as well.

• 설비공학논문집
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• 제21권9호
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• pp.483-495
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• 2009

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle-installed downstream of the high pressure turbine extraction stream line-inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes operation of experience and numerical analysis composed similar condition with real high pressure feedwater heater. This study applied squared, curved and new type impingement baffle plates to feedwater heater same as previous study. In addition, it shows difference of pressure distribution and value between single phase and two phase based on experience and numerical analysis.

• 한국유체기계학회 논문집
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• 제5권4호
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• pp.32-39
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• 2002

The purpose of this 3-D numerical simulation is to calculate and examine the complex 3-D stall phenomena on the rotor blade and wake distribution of the wind turbine. The flow characteristics of 500kW Horizontal Axis Wind Turbine (HAWT) are compared with the calculated 3-D stall phenomena and wake distribution. We used the CFX-TASCflow to predict flow and power characteristics of the wind turbine. The CFD results are somewhat consistent with the BEM (Blade Element Momentum) results. And, the rotational speed becomes faster, the 3-D stall region becomes smaller. Moreover, the pressure distribution on the pressure side that directly gets the incoming wind grows high as it goes toward the tip of the blade. The pressure distribution on the blade's suction side tells us that the pressure becomes low in the leading edge of the airfoil as it moves from the hub to the tip. However, we are not able to precisely predict on the power coefficient of the rotor blade at the position of generating complex 3-D stall region.

• 연구논문집
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• 통권27호
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• pp.87-99
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• 1997

Present paper describes on/off design performance of a 50KW turbogenerator gas turbine engine for hybrid vehicle application. For optimum design point selection, relevant parameter study is carried out. The turbogenerator gas turbine engine for a hybrid vehicle is expected to be designed for maximum fuel economy, ultra low emissions, and very low cost. Compressor, combustor, turbine, and permanent-magnet generator will be mounted on a single high speed (82,000 rpm) shaft that will be supported on air bearings. As the generator is built into the shaft, gearbox and other moving parts become unnecessary and thus will increase the system's reliability and reduce the manufacturing cost. The engine has a radial compressor and turbine with design point pressure ratio of 4.0. This pressure ratio was set based on calculation of specific fuel consumption and specific power variation with pressure ratio. For the given turbine inlet temperature, a rather conservative value of $1100^\circK$ was selected. Designed mass flow rate was 0.5 kg/sec. Parametric study of the cycle indicates that specific work and efficiency increase at a given pressure ratio and turbine inlet temperature. Off design analysis shows that the gas turbine system reaches self operating condition at N/$N_{DP}$ = 0.53. Bleeding air for turbine stator cooling is omitted considering low TIT and for a simple geometric structure. Various engine performance simulations including, ambient temperature influence, surging at part load condition. Transient analysis were performed to secure the optimum engine operating characteristics. Surge margin throughout the performance analysis were maintained to be over 80% approximately. Validation of present results are yet to be seen as the performance tests are scheduled by the end of 1998 for comparison.

• 한국전산유체공학회지
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• 제19권4호
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• pp.14-19
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• 2014

This study conducts shape optimization of rib turbulator on the internal cooling passage that has triangular cross-section of high pressure turbine nozzle. During optimization, various types of rib turbulator including angled, V-shaped, A-shaped and angled rib with intersecting rib are considered. Each type of rib turbulator is parameterized with attack angle(s), rib height, spacing ratio and bending/intersecting location. For optimization, Design of Experiment (DOE) and Kriging surrogate model are used to utilize computational resource more efficiently and Genetic Algorithm (GA) is used to search the optimum points. As a result, Pareto front of each type of rib turbulator with friction factor that relates to pressure drop in cooling passage and spatially averaged Nusselt number that relates to heat transfer on the wall is drawn and optimum points on the Pareto front are suggested.

• 전기전자학회논문지
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• 제23권2호
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• pp.675-680
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• 2019

석탄화력발전소는 저부하에서 효율 향상을 위해 변압운전으로, 고부하에서는 정압으로 운전하는 복합변압운전 방식으로 운전하고 있으며, 복합변압운전에는 2밸브 및 3밸브 전개모드로 구분되어 운영되고 있다. 각 발전소는 제작사 권고에 따라 터빈제어밸브 모드를 선택하여 운전하고 있으나 최적의 변압운전 부하범위로 운전되고 있지 않고, 각 발전소별 부하범위 또한 상이하게 구성 되어있다. 최적의 변압운전 부하범위로 설정되지 않으면 터빈밸브 교축 손실 발생에 따른 고압터빈 내부효율 저하가 발생되어 플랜트 효율이 저하된다. 이러한 문제점을 개선하기 위해 본 논문에서는 터빈제어밸브 모드별 최적의 변압운전 부하 범위를 개선하기 위해 각 부하별 열 성능 분석 방법을 통해 최적의 부하범위를 선정하고자 한다.