• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.561-566
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• 2011

In this paper, 1-D design of axial flow hydraulic turbine including runner blades, spiral casing with distributors(guide vanes and stay vane), and draft tube was conducted and then 3-D flow analysis was carried out using CFX-12.1. The results of 3 runners showed that with an increase in the number of blades, the flow rate and the power of the turbine system increased. On the other hand. the runner loss was not directly connected with the number of blades. As a result, proper blade number could be selected and more than 100kW small hydraulic turbine could be designed.

• 한국추진공학회지
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• 제9권3호
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• pp.10-17
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• 2005

축류형 터빈이 부분분사에 의하여 작동하는 경우에 성능을 예측하는 모델을 개발하였다. 부분분사에 의하여 작동하는 터빈에서 발생되어지는 손실을 windage 손실, 확산손실, 혼합손실로 분류하여 각각의 모델을 적용하여 효율을 예측하였으며 실험의 결과와 비교하였다. 타 모델과는 달리 세 가지의 손실을 모두 고려한 본 연구의 결과가 실험결과와 잘 일치하고 있음을 보였으며 부분 분사량을 변경한 경우에도 실험결과와 일치된 결과를 보였다. 본 연구의 예측모델은 부분분사 터빈의 성능을 예측하는데 적용 되어질 뿐만 아니라 높은 예측정확도를 보였다.

• Advances in aircraft and spacecraft science
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• 제10권3호
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• pp.245-256
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• 2023

In order to improve aerodynamic performance of multi-stage axial flow turbines used in aircraft engines, a one-dimensional aerodynamic design and optimization framework is constructed. In the method, flow path is generated by solving mass continuation and energy conservation with loss computed by the Craig & Cox model; Also real gas properties has been taken into consideration. To obtain an optimal result, a multi-objective genetic algorithm is used to optimize the efficiencies and determine values of various design variables; Final design can be selected from obtained Pareto optimal solution sets. A three-stage axial turbine is used to verify the effectiveness of the developed optimization framework, and designs are checked by three-dimensional CFD simulation. Results show that the aerodynamic performance of the optimized turbine has been significantly improved at design point, with the total-to-total efficiency increased by 1.17% and the total-to-static efficiency increased by 1.48%. As for the off-design performance, the optimized one is improved at all working points except those at small mass flow.

• 산업기술연구
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• 제14권
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• pp.39-48
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• 1994

Up to the present the study on the performance prediction of HAWT was perfomed 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 Glaurert method with the experimental results, it was proved that our method was a very efficient method.

• 한국유체기계학회 논문집
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• 제12권1호
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• pp.22-27
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• 2009

The important problems that arise in the design and performance of the axial flow turbine are the prediction and control of secondary flows. Some progresses have been made on understanding flow conditions that occur when the inlet endwall boundary layer separates at the point in the endwall and rolls up into the horseshoe vortex. And the flows though an axial turbine tend to be extremely complex due to its inherent unsteady and viscous phenomena. The passing wakes generated from the trailing edge of the stator make an interaction with the rotor. Unsteady flow should be considered rotor/stator interactions. The main purpose of this research is control of secondary flow and improvement efficiency in turbine by leading edge modification in unsteady state. When the wake from the stator ran into the modified leading edge of the rotor, the leading edge generated the weak pressure fluctuation by complex passage flows. In conclusion, leading edge modification(bulb2) results in the reduced total pressure loss in the flow field.

• 한국정밀공학회지
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• 제22권12호
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• pp.149-155
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• 2005

The rotating components such as turbine rotors in service are generally subjected to multiaxial cyclic loading conditions. The prediction of fatigue lift for turbine rotor components under complex multiaxial loading conditions is very important to prevent the fatigue failures in service. In this paper, axial and torsional low cycle fatigue tests were preformed for 3.5NiCrMo steels serviced low pressure turbine rotor of nuclear power plant. Several methods to predict biaxial fatigue life such as Tresca, von Mises and Brown & Miller's critical plane approach were evaluated to correlate the experimental results for serviced NiCrMoV steel. The fracture mode and fatigue characteristics of NiCrMoV steel were discussed based on the results of fatigue tests performed under the axial and torsional test conditions. In particular, the Brown and Miller's critical plane approach was found to best correlate the experimental data with predictions being within a factor of 2.

• 한국유체기계학회 논문집
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• 제18권5호
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• pp.33-41
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• 2015

Organic Rankine cycle (ORC) has been used to generate electrical or mechanical power from low-grade thermal energy. Usually, this thermal energy is not supplied continuously at the constant thermal energy level. In order to optimally utilize fluctuating thermal energy, an axial-type turbine was applied to the expander of ORC and two supersonic nozzle were used to control the mass flow rate. Experiment was conducted with various turbine inlet temperatures (TIT) with the partial admission rate of 16.7 %. The tip diameter of rotor was to be 80 mm. In the cycle analysis, the output power of ORC was predicted with considering the load dissipating the output power produced from the ORC as well as the turbine efficiency. The predicted results showed the same trend as the experimental results, and the experimental results showed that the system efficiency of 2 % was obtained at the TIT of $100^{\circ}C$.

• 한국추진공학회지
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• 제12권6호
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• pp.21-29
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• 2008

본 연구에서는 부분분사에서 작동하는 소형 축류형 터빈에서, 중요한 설계변수인 노즐에서의 출구유동각과 동익에서의 현절비를 변경하였을 때 발생되는 성능변화에 대하여 실험적인 연구를 수행하였다. 성능시험에 사용된 터빈은 단단으로 구성되며 로터의 평균반경은 35mm였다. 실험에서 최적의 설계변수를 찾기 위하여 세 가지의 현절비와 네 가지의 노즐에서의 출구유동각을 적용하였다. 터빈에서의 전체적인 성능평가를 위하여 총비출력으로 비교하였으며, 부분분사율이 3.4%인 경우에 동익에서의 현절비가 2.18일 때 최고의 성능이 얻어졌다. 이 값은 전분사 시에 적용되는 최적의 현절비에 비하여 74%나 증가한 결과이다.

• 대한기계학회논문집B
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• 제23권7호
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• pp.831-840
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• 1999

In this work, an aerothermodynamic calculation model for cooled axial flow turbine blades with trailing edge ejection is suggested and a mean line performance analysis of a turbine stage with nozzle cooling is carried out. A unique model regarding the interaction between coolant and main gas is proposed, while existing correlations are adopted to predict viscous loss and blade outflow angle. The interactions considered are the heat transfer from main gas to coolant and the temperature and pressure losses by the mixing of two streams due to the trailing edge coolant ejection. For a stator blade without ejection, trailing edge loss calculated by the trailing edge analysis is compared with that calculated by loss correlation. The effect of heat transfer effectiveness of coolant passage on the mixing loss is analyzed. For a model turbine stage with nozzle cooling, parametric analyses are carried out to investigate the effect of main design variables(coolant mass flow ratio, temperature and ejection area) on the stage performance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.771-776
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• 2001

By matching a well established fast throughflow code, with standard loss correlations, and an efficient optimization algorithm, a new design system has been developed, which optimizes inlet and exit flow-field parameters for each blade row of a multistage axial flow turbine. The compressible steady state inviscid throughflow code based on streamline curvature method is suitable for fast and accurate flow calculation and performance prediction of a multistage axial flow turbine. A general purpose hybrid constrained optimization package, iSIGHT has been used, which includes the following modules: genetic algorithm, simulated annealing, modified method of feasible directions. The design system has been demonstrated using an example of a 5-stage low pressure steam turbine for 800MW thermal power plant previously designed by HANJUNG. The comparison of computed performance of initial and optimized design shows significant improvement in the turbine efficiency.