• Plant Journal
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• v.13 no.4
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• pp.48-50
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• 2017

A program for analyzing the transient behaviors of industrial gas turbines was developed. Each component (compressor, combustor, turbine and ducts)of gas turbine is modeled as a fully module to enhance the expandability of the program. We used object-oriented programing for this purpose. The mass and energy balance equations are solved numerically by Multivariable Newton Raphson method. The characteristic maps for the compressor and turbine were used for predicting the performance of a gas turbine engine. Combustion in the combustor is assumed to be complete combustion. PID control is used to maintain constant rotational speed and turbine exhaust temperature by the control of the fuel flow rate and the changing of the compressor inlet guide vane angle at the same time. It was confirmed that stable control of the gas turbine was possible, even for a rapid load change.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.735-743
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• 2015

The major component with a significant impact on the thermodynamic efficiency of the organic Rankine cycle is the turbine. Many difficulties occur in the turbine design of an organic Rankine cycle because the expansion process in an organic Rankine cycle is generally accompanied by a dramatic change in the working fluid properties. A precise preliminary design for a radial inflow turbine is hard to obtain using the classic method for selecting the loading and flow coefficients from the existing performance chart. Therefore, this study proposed a method to calculate the loading and flow coefficient based on the number of rotor vanes and thermodynamic design requirements. Preliminary design results using the proposed models were in fairly good agreement with the credible results using the commercial preliminary design software. Furthermore, a numerical analysis of the preliminary design results was carried out to verify the accuracy of the proposed preliminary design models, and most of the dependent variables, with the exception of the efficiency, were analyzed to meet the preliminary design conditions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.1
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• pp.15-21
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• 2006

Parametric cycle analysis of a dual-spool, mixed exhaust turbofan engine with turbine blade cooling were described to investigate the effect of turbine blade cooling on the engine performance such as specific thrust and thrust specific fuel consumption. Coolant of low pressure turbine triggers high engine performance loss and cooling effect loss in high pressure turbine. Therefore low pressure turbine coolant should be much more considered for effective design.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.662-667
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• 2000

A simulation procedure for a full transient analysis of the start-up of heavy-duty gas turbines for power generation is constructed. Compressor stages are grouped into three categories (front, mid, rear) and three different stage characteristic curves are applied to consider the different low-speed operating characteristics. Start-up behavior of a typical single-shaft gas turbine for power generation is simulated. The predicted transient behavior shows a good agreement with the field data. Special attention is paid to the effects of the modulation of VIGV on start-up characteristics, which play a key role in the stable operation of gas turbines.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3247-3252
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• 2007

Endwall losses contribute significantly to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratio are increased. Hence, reducing the extend and intensity of the secondary flow structures helps to enhance overall efficiency. From the large range of viable approaches, a promising combination positioning and height of endwall contouring was chosen. The objective of this study is to document the three-dimensional flow in a turbine cascade in terms of streamwise vorticity, total pressure loss distribution and static pressure distribution on the endwall and blade surface and to propose an appropriate positioning and height of the endwall contouring which show best secondary, overall loss reduction among the simulated endwall. The flow through the gas turbine were numerically analyzed using three dimensional Navier-Stroke equations with a commercial CFD code ANSYS CFX-10. The result shows that the overall loss is reduced near the flat endwall rather than contoured endwall, and the case of contoured endwall installed at 30% from leading edge with height of 25% for span showed best performance.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.158-162
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• 2000

Secondary flows in gas turbines, especially those associated tip clearance and labyrinth seals, have become a focus of interest for engine manufacturers. In the past, many analytical and experimental studies, which focused solely on the flows in either tip clearances or seals, have been conducted. This paper presents an analytical model that describes the flow response in a single stage turbine induced by a finite sealing gap at the turbine rotor. The flow is assumed to be axisymmetric and the analysis is done in the meridional plane. Upon going through the stage, the radially uniform upstream flow is assumed to split into two streams one associated with the seal and the other which has gone through the blades. The former is referred to as the leakage flow, and the latter is referred the as the passage flow. The passage flow is assumed to be inviscid and incompressible while the flow in the seal can be modeled as either inviscid or viscous. Thus, the model is capable of predicting the kinematic effects of labyrinth seals on the turbine flow field.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.255-265
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• 1996

Up to the present the study on the performance prediction of HAWT was performed mainly by assuming the axial flow. So in this paper we aimed at the fully non-axial flow of HAWT. For this purpose, we defined the wind turbine pitch angle in addition to the yaw angle to specify the arbitrary wind direction. And we adopted the Glauert method as the basic analysis method then modified this method suitably for our goal. By comparing the computational results obtained by this modified new Glauert method with the experimental results, it was proved that our method was a very efficient method. And on the basis of the reliability of this method we considered the effect of all the design parameters and presented the optimum blade geometry and the optimum operating condition to gain the best performance curve.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.17-17
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• 1999

충돌제트는 산업, 항공우주, 군사 분야 등 공학적으로 많은 분야에서 응용되고 있다. 산업분야에서 충돌제트는 설치가 간단하고 형태가 단순하면서도 열 및 물질 전달효과가 상당히 크기 때문에 고효율의 열전달 효과를 얻을 수 있다는 점에서 광범위하게 응용된다. 예를 들면 물체 표면의 부분냉각은 고온 금형의 급속 냉각, 가스터빈 깃의 냉각, 전자부품의 냉각 등에 이용되며 부분 가열에서는 제철, 제지 및 유리공업, 금형의 풀림 등에 폭 넓게 적용된다. 항공우주, 군사분야에서는 수직/단거리 이·착륙기(V/STOL)의 발진, 미사일 발사시스템, 다단 로켓의 분리, 우주공간에서의 도킹, 화염 편향기 등에 적용이 되며 대부분 평판이나 특수한 판의 형상에 과소 팽창제트가 충돌할 때 발생하는 현상에 대한 것이다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.192.1-192.1
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• 2010

Micro hydraulic turbines take a growing interest because of its small and simple structure as well as high possibility of applying to micro and small hydropower resources. The differential pressure exiting within the city water pipelines can be used efficiently to generate electricity like the energy generated through gravitational potential energy in dams. In order to reduce water pressure at the inlet of water cleaning centers, pressure reducing valves are used widely. Therefore, pressure energy is wasted. Instead of using the pressure reduction valve, a micro counter-rotating hydraulic turbine can be replaced to get energy caused by the large differential pressure found in the city water pipelines. In this paper, detail studies have been carried out to acquire basic design data of micro counter-rotating hydraulic turbine, output power, head, and efficiency characteristics on various number of runner vane. Moreover, the influences of pressure, tangential and axial velocity distributions on turbine performance are also investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.89-96
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• 2006

The combustion temperature in gas generator should be kept below around 1,000K to avoid any possible thermal damages to turbine blade by adopting either fuel rich or oxidizer rich combustion. Thus, non-equilibrium chemical reaction dominates in the gas generator. Meanwhile, Kerosene is a compounded fuel mixed with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focus to model the non-equilibrium chemical reaction of kerosene/LOX with detailed kinetics developed by Dagaut using PSR(Perfectly stirred reactor) assumption. Also, droplet evaporation time is taken into account by calculating for the residence time of droplet and by decoupling reaction temperature from the reactor temperature. In Dagaut’s surrogate model for kerosene, chemical kinetics of kerosene consists of 1592 reaction steps with 207 chemical species. The comparison of calculation results with experimental data could provide very reliable and accurate numbers in the prediction of combustion gas temperature, species fraction and other gas properties.