• 한국항공우주학회지
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• 제42권1호
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• pp.1-9
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• 2014

본 논문은 고속압력감응페인트기법(Fast-Responding PSP)을 소개하고, 이를 이용하여 정지비행상태에 있는 축소형 로터 블레이드의 표면(윗면) 압력을 측정해봄으로서 PSP를 이용한 로터 블레이드 표면 압력 측정의 정확성과 그에 따른 실험기법의 타당성을 검증하기 위하여 수행되었다. 실험을 위한 광원으로는 532 nm 파장을 가지는 Pulsed laser를 사용하였고, PSP 측정 기법으로는 Lifetime 기법을 적용하였다. 또한, 모델 표면에 도포된 압력감응페인트는 반응성이 높은 Porous PSP가 사용되었다. 로터 블레이드는 NACA0012 익형을 가지고 있으며 길이 340 mm, 코드 40 mm의 직사각 형상 1종과 끝단의 후퇴각이 다른 4종의 형상을 사용하였다. 로터 블레이드의 콜렉티브 피치각 변화에 따른 표면 압력 분포를 측정하였으며 측정된 결과를 통해 콜렉티브 피치각이 증가할수록 윗면의 압력이 낮아지는 것을 정성적으로 확인하였고, 정량적인 압력계수는 NASA의 실험 데이터와 비교하여 약 0.4~0.7 정도 높은 경향성을 보였다.

• 한국정밀공학회지
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• 제20권9호
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• pp.118-125
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• 2003

In this study, we carried out the finite element analysis for the screw of centrifuge that is the weakest part of the centrifuge for sewage management. Centrifugal force caused by rotation with velocity of 4000rpm was applied at the screw. Structural analysis was done with respect to the change of the ratio of blade pitch($R_P$), shaft diameter($R_D$) and extended hole($R_E$). When the area of circular hole is equal to that of extended holes, maximum equivalent stresses in the screw with circular and extended circular hole were compared. And then natural frequency analysis was executed for the same model. Three mode shapes were used to explain the vibration characteristics of each screw. Convergence study was accomplished fur more accurate results.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.354-359
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• 2011

This study proposes a design for an airborne wind turbine generator. The proposed system comprises a cycloidal wind turbine adopting a cycloidal rotor blade system that is used at a high altitude. The turbine is mounted on a tethered balloon. The proposed system is relatively easier to be realized and stable. Moreover, the rotor efficiency is high, which can be adjusted using the blade pitch angle variation. In addition, the rotor is well adapted to the wind-flow direction change. This article proves the feasibility of the proposed system through a sample design for a wind turbine that produces a power of 30 kW. The generated wind power at 500 m height is nearly 3 times of that on the ground.

• 한국태양에너지학회 논문집
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• 제28권1호
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• pp.25-32
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• 2008

Aeroelastic phenomena of a wind turbine include stall-induced vibrations and classical flutters. The classical flutter occurs due to coalescence between bending mode and torsion mode. It is typically the aeroelastic instability of an aircraft wing. Different from the classical flutter, the stall-induced vibration is the instability in lead-lag mode due to negative aerodynamic dampings. In the present study, the three degree of freedom aeroelastic model of a wind turbine blade is introduced to characterize and analyze its aeroelastic phenomena. The numerical results show that the aeroelastic stability of flap-lag motion is more unstable than that of flap-pitch motion and the aeroelastic characteristics of lead-lag motion can become unstable as wind speed increases.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.839-847
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• 2004

In this study, the flow characteristics within supersonic cascades are numerically investigated by using Fine Turbo, a commercial CFD code. Cascade flows are computed for three different inlet conditions. : a uniform supersonic inlet condition, a linear nozzle and a converging-diverging nozzle located in front of cascades. The effect of inlet conditions is compared and flow characteristics including shock patterns and shock-boundary layer interaction are analyzed. Also the effect of design parameters such as pitch-chord ratio, blade angle and blade surface curvature on the flow within supersonic cascades are studied.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.424-428
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• 2004

A wind turbine system converts wind energy into electric energy, the system operated under normal environmental conditions. In case of particular turbulent wind flow such as typhoon, hurricane etc, the control of a blade used to a yaw control and a pitch control method. A small wind turbine has not a speed control system to only a manual tail safety brake. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The controller composed of wired motor, relay system, steel wired motor him down a perpendicular to wind flow and then the blade speed reduced high to zero. The operation of automatic tail safety controller verified by manual test.

• 대한기계학회논문집B
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• 제20권1호
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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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.495-498
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• 2006

The Kaplan turbine model has been tested and analyzed. The blade angle and the guide vane opening of the turbine model were designed to be varied according to the best combination of guide vane and runner blade opening. When the changes in head and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed model in this study will be suitable for small hydropower stations with large changes In head and load such as agricultural reservoir.

• 한국추진공학회지
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• 제8권1호
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• pp.70-80
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• 2004

본 연구에서는 한국과 같이 비교적 저 풍속인 지역에 적용 가능하도록 피치제어장치를 가진 1kW급 소형 풍력발전 시스템의 개발 결과를 제시하였다. 공력설계에서는 블레이드의 직경이 동급의 상용 블레이드 보다 과도하게 크지 않으면서도 저 풍속 지역에서 보다 효율적인 형상설계를 위해 여러 가지 설계 변수분석을 통한 파라미터 연구가 수행되었다. 또한 구조설계를 통해 풍력발전기에 작용하는 다양한 하중을 효과적으로 견딜 수 있는 경량의 복합재 구조가 설계되었다. 구조설계의 평가를 위해 유한요소 구조해석이 수행되었으며, 실물 구조시험을 수행하여 구조적 안전성을 확인하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.522-525
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• 2008

A vacuum cleaner is the widely used home equipment. However, it has a trouble with too much power consumption. Most losses occur at the centrifugal fan. To remedy this trouble the investigation of motor, which is the main component of vacuum cleaner, is required. The flow characteristics around the high-speed rotating centrifugal fan which is influenced by the very low inlet pressure is quite different from a commonly used fan. Hence it is quite difficult to analyze the flow by the experimental means or by the numerical simulation. In this research, it is aimed to improve the air-suction performance of a vacuum cleaner through the flow analysis around a motor. The efficiency of the centrifugal fan is affected by blade shape, blade number, blade pitch, etc. The influence of the shape of impeller on the flow is investigated in this study. The flow around the centrifugal fan is simulated by applying the moving mesh. To verify the validity of the computation results, the air flow rate and the pressure field to the cleaner is compared with the experimental data. All simulations are performed by using commercial code SC/Tetra. The calculated results show good agreement with the experimental ones and it is believed to be promising to use computational simulation in the improvement of the vacuum cleaner performance.