• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.298-303
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• 2002

Dispersion of coolant jets in a film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. In order to investigate the effect of blowing ratios on the film cooling of turbine blade, cylindrical body model was used. Mainstream Reynolds number based on the cylinder diameter was $7.1{\times}10^4$. The effect of coolant flow rates was studied for blowing ratios of 0.7, 0.9, 1.2 and 1.5, respectively. The temperature distribution of the cylindrical model surface is visualized by infrared thermography (IRT). Results show that the film-cooling performance could be significantly improved by the shaped injection holes. For higher blowing ratio, the spanwise-diffused injection holes are better due to the lower momentum flux away from the wall plane at the hole exit.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.261-264
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• 2006

This paper describes the effects to wind turbine blade aerodynamics due to interaction between blade and tower on upwind type HAWT. In order to analyze effects of blade-tower interact ion, the analyst s program WINFAS which is based on VLM(Vortex Lattice Method), Free wake and FVE model is used. In this study, the changes of wind turbine blade aerodynamics caused by blade-tower interact ion are Investigated with various parameters windshear, yaw error, TSR and tower diameter.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.157-160
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• 2006

A turbo-expander is developed for the regeneration in the expansion process. The turbo-expander operates in the partial admission and supersonic flow, and an axial-type single stage turbine is applied to the turbo-expander. Its outer diameter is 82mm and the operating gas is R134a. A 15kW reciprocating compressor is applied in this experiment and the turbo-expander is installed in the expansion process instead of the commonly using expansion valve. Two supersonic nozzles are applied for the expansion process. The high speed of R 134a after passing the supersonic nozzles gives the impulse force to the turbo-expander and some powers are generated on this process. A generator is installed at the end of the turbo-expander shaft. The generating output power from the turbo-expander is controlled by the power controller. Pressures and temperatures are measured on the lines for the performance investigation. More than 600W/(kg/sec) are generated in this experiment.

• International Journal of Fluid Machinery and Systems
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• 제1권1호
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• pp.169-180
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• 2008

As a major component of a power plant, a turbine generator must have sufficient reliability. Longer blades have lower natural frequency, thereby requiring that the design of the shaft and blade takes into account the coupling of the blade vibration mode, nodal diameter k=0 and k=1 with vibration of the shaft. The present work analyzes the coupling of the translation motion of the shaft with in-plane vibration of the blades with k=1 modes. At a rotational speed ${\Omega}_1=|{\omega}_s-{\omega}_b|$, the resonance of the blades has a relatively large amplitude. A violent coupled resonance was observed at a rotational speed ${\Omega}_2=|{\omega}_s+{\omega}_b|$. Resonance in blade vibration at ${\Omega}_1=|{\omega}_s-{\omega}_b|$ was experimentally confirmed.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.426-430
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• 2009

In order to investigate the design method for a micro centrifugal compressor, which is the most important component of an ultra micro gas turbine, an impeller having the outer diameter of 20mm was designed, manufactured and tested. The designed rotational speed is 500,000 rpm and the impeller has a fully 3-dimensional shape. The impeller was rotated at 250,000 rpm in the present study. The experimental results of the tested compressor with the vaned and the vaneless diffusers were compared. It was found that the vaned diffuser attained the higher flow rate than the vaneless diffuser at the maximum pressure ratio. In addition the maximum pressure ratio was higher for the diffuser having a larger diffuser divergence angle at the high flow rate. These results were compared with those obtained by the prediction method used at the design stage.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.560-564
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• 2004

The optimal design and combustion analysis of the gas generator for Liquid Rocket Engine (LRE) were performed. A fuel-rich gas generator in open cycle turbopump system was designed for 10ton$_{f}$ in thrust with RP-1/Lox propellant. The optimal design was done for maximizing specific impulse of main combustion chamber with constraints of combustion temperature and power matching required by turbopump system. Design variables were selected as total mass flow rate to gas generator, O/F ratio in gas generator, turbine injection angle, partial admission ratio, and turbine rotational speed. Results of optimal design show the dimension of length, diameter, and contraction ratio of gas generator. Also, the combustion test was conducted to evaluate the performance of injector and combustion chamber. And the effect of the turbulence ring was investigated on the mixing enhancement in the chamber.r.

• International Journal of Fluid Machinery and Systems
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• 제3권4호
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• pp.360-368
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• 2010

This paper describes the flow field and the blade pressure distribution of a horizontal axis wind turbine in various yawed flow conditions. These measurements were carried out with 2.4m-diameter rotor with pressure sensors and a 2-dimensional laser Doppler velocimeter for each azimuth angle in a wind tunnel. The results show that aerodynamic forces of the blade based on the pressure measurements change according to the local angle of attack during rotation. Therefore the wake of the yawed rotor becomes asymmetric for the rotor axis. Furthermore, the relations between aerodynamic forces and azimuth angles change according to tip speed ratio. By the experimental analysis, the flow field and the aerodynamic forces for each azimuth angle in yawed flow condition were clarified.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.81-84
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• 2002

Dispersion of coolant jets in a film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. In order to investigate the effect of blowing ratios on the film cooling of turbine blade, cylindrical body model was used. Mainstream Reynolds number based on the cylinder diameter was $7.1\;\times\;10^4$. The free-stream turbulence intensity kept at $5.0\%$ by using turbulence grid. The effect of coolant flow rates was studied for blowing ratios of 0.9, 1.3 and 1.6, respectively. The temperature distribution of the cylindrical model surface is visualized by infrared thermography (IRT). Results show that the film-cooling performance may be significantly improved by controlling the blowing ratio. As blowing ratio increases, the adiabatic film cooling effectiveness is more broadly distributed and the area protected by coolant increases. The mass flow rate of the coolant through the first-row holes is less than that through the second-row holes due to the pressure variation around the cylinder surface.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.319-322
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• 2006

Under the national project for the development of 2MW wind energy convert system, we are under development of the prototype of 2MW wind turbine with low speed gearbox. This system adopts low speed gear box with planetary and spur gear and is pitch regulated variable speed type with the synchronous permanent magnet generator. The compromised size of generator in diameter and width are adopted to meet the structural design requirements. In this paper, the concept study for the type, the aerodynamic design for the blade and the details of load calculation will be presented. The detailed characteristics of the system will also be introduced.

• 대한기계학회논문집A
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• 제37권10호
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• pp.1201-1206
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• 2013

풍력 발전 블레이드의 제조 및 운영 중에 발생하는 결함들은 블레이드의 수명과 안전성에 큰 영향을 미친다. 일반적으로 블레이드의 제조 과정에서는 박리, 기공, 주름, 모재 균열 등과 같은 결함이 발생한다. 본 연구에서는 이미지 상관 기법을 이용하여 변형률 분포를 확인함으로써 블레이드의 제조 과정에서 주로 나타나는 결함 중 하나인 기공 결함의 검출능을 조사하였다. $0^{\circ}/{\pm}45^{\circ}$의 섬유 방향을 가진 4 Ply 로 적층된 GFRP 복합재 시험편에 인공적인 기공 결함을 삽입하여 기공의 크기 및 위치에 따른 검출 의존성을 조사하였다. 기공의 크기는 지름 1, 2, 3 mm 이며, 기공의 위치는 시험편 표면으로부터 0.5, 1.0, 1.5 mm 깊이에 삽입하였다. 부하된 시험 하중은 최대 200 MPa 이며, 이미지 상관 기법을 통해 변형률 분포를 획득하여 지름 2, 3 mm의 기공과 깊이 0.5, 1.0 mm의 기공 결함을 검출할 수 있었다.