• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.41-41
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• 2000

터어빈 블레이드의 경우 제작 또는 설계상의 이유로 뭉툭한 끝단을 가질 수밖에 없게 되는데, 이로 인하여 같은 터보기계인 압축기 블레이드의 경우와는 다르게 블레이드 끝단에서 끝단 와류(Trailing edge vortex)가 발생하게 된다. 이 와류는 블레이드의 손실 증가, 고주파 음파의 생성, 국부적으로 매우 큰 열 전달 및 에너지분산 등 터빈 블레이드의 성능에 좋지 못한 영향을 미치게 된다. 또한 와류와 충격파와의 간섭효과 둥이 존재하는 경우에는 매우 복잡한 유동장을 형성하며 심한 유동 구배가 존재하게 되므로 고해상도의 수치해석 방법이 아니고서는 이를 수치적으로 해석하기가 쉽지 않다.(중략)

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.382-386
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• 2013

본 연구에서는 Main Rotor Blade Tip 형상 변화에 따른 후류해석을 통해 와류 생성 및 주변 유동을 분석하여 블레이드 팁 형상의 변화가 와류 간섭을 감소시키는지의 여부를 확인하였다. EDISON CFD를 이용하여 블레이드 Blade Tip 형상에 따라 유동이 어떻게 나타나며, Blade 후류의 압력과 점성의 변화를 분석하여 와류의 양상을 해석하였다. 비교 Blade 형상은 2세대 긴 직사각형 모형, KUH 수리온의 Blade, 유로콥터사의 'Blue Edge'로 비교적 최근에 개발된 대표적인 Blade Tip 형상 3개로 정하였다. 결과를 토대로 블레이드 뒷전의 와류흐름 양상을 확인하여 블레이드 와류 간섭현상의 감소를 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.293-296
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• 2008

본 연구에서는 BEMT와 gradient method를 이용하여 블레이드를 설계한 후 이에 대한 세밀한 유동장 해석을 위하여 CFD 기법을 적용하였다. CFD의 경우 해석시간의 문제로 설계단계에서의 적용에 어려움이 따른다. 따라서 설계 단계에서는BEMT를 적용하는 것이 적절하다. 그러나 BEMT의 경우 기법의 한계로 인하여 세밀한 유동의 해석에 어려움이 따른다. CFD의 경우 전체 유동장 및 블레이드 표면에서의 자세한 물성치 분석에 유리한 점을 가진다. 본 연구에서는 두가지 해석 기법의 장점을 살려 설계단계에서는 BEMT를 적용후 결과물인 블레이드 형상에 대하여 CFD 해석을 수행하여 유동장 해석을 하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.170-177
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• 2013

This study is focused on the shape design and flow analysis on a 200 W-class Gyromill type vertical axis wind turbine rotor blade. Single tube theory is adopted for the shape design of the turbine blade. 2-dimensional CFD analysis is conducted to examine the turbine performance with basic shape, and then 3-dimensional shape is determined from the examination of the performance. By the CFD analysis on the 3-dimensional shape of the wind turbine, performance of the turbine is examined and also, shape of the wind turbine rotor blade is determined accordingly. From the results of this study, a 200 W-class Gyromill type vertical axis wind turbine rotor blade is designed and the reliability of the design method is confirmed by CFD analysis.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.698-701
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• 2005

본 연구에서는 풍력발전용 블레이드에 대한 일방향 유동/구조 연성해석을 하였다. 계산에 사용된 모델은 100kW급 풍력발전기 블레이드이며 정격용량은 42rpm이다. 유동영역에 대한 계산은 블레이드 표면에 작용하는 압력데이터를 얻기 위하여 행해지고 구조해석에서는 같은 모델에 대하여 얻어진 압력데이터를 하중조건으로 적용하여 풍력발전기의 변위 및 최대응력값을 계산한다. 계산결과 최대응력이 발생하는 지점은 날개의 후면 허브부분인 것으로 나타났다. 입구속도가 증가할수록 전면과 후면에 작용하는 압력차로 인해 출력과 최대변위는 포물선 형태로 증가함을 알 수 있었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.1
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• pp.93-101
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• 2000

In a gas-turbine engine, fan blades in flow path are confronted with many kinds of loading. The study of the excited force by the wake of struts has proposed and the possibility of fatigue failure about rotating fan blades by the excited force at the steady state is evaluated. Equations of the excited force of wakes has been derived at the steady state and the maximum pressure distributions measured at the transient state are proposed. Dynamic characteristics and the fatigue strength of fan blades by experimental test were obtained. To evaluate HCF(High Cycle Fatigue) damage of fan blades, FEM analysis was performed with a steady state harmonic response, which was followed by high cycle fatigue damage factor from goodman diagram.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.94-97
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• 2008

As the partial admission turbine has a intrinsically unsteady and three dimensional flow region, numerical calculation time of these study has been too long time. The numerical analysis for gas temperature of turbine blade surface has been performed to investigate development of temperature with various pyro start pressure. Computations have been carried out several turbine rotational speeds in the range from 0 to 16000 rpm and inlet conditions with 1423K, 7.2MPa. As a result, the more rotational speed and pyro starter pressure of turbine increased, the more turbine blade's temperature decreased. It is also found that flow field of turbine blade inlet area at pyro starter pressure of 5.75MPa and rotational speed of 12100 rpm formed surface temperature uniformly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.675-680
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• 2017

Considering that most sewage treatment facilities have a water head of less than 2.0 m and a constant flow rate, the development of a small hydro power generation device capable of maintaining stable power generation and efficiency is urgently needed. In this study, a numerical analysis using the CFD code was carried out to develop a drag force type vertical axis hydro turbine for the improvement of the production efficiency of small-scale hydro energy underlow flow velocity conditions. The blade pressure changes and internal flows were analyzed in the presence or absence of hydro turbine blade holes at a flow velocity of less than 2.0 m/s. The pressure distribution of the hydro turbine blades with holes was found to be about 5.1 % lower than that of the hydro turbine blades without holes. The analysis of the internal flow around the water tank and hydro turbine blade revealed that the flow velocity varied with the vector distribution and that the flow velocity of the hydro turbine blades with holes was 5.6 % less than that of the hydro turbine blades without holes. It is believed that forming a hole in the blade may be helpful for its structural safety.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.2
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• pp.205-213
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• 2011

The characteristics of noise generation in the suction nozzle of a vacuum cleaner are analyzed numerically and experimentally. First, the flow resistance induced by each element in the suction nozzle of a vacuum cleaner with a double-blade rotary fan is investigated numerically and its relation with flow-induced noise and suction performance is examined in an anechoic room. The flow resistance and vorticity in the suction nozzle are calculated, and it is found that they are closely related to flow-induced noise and that the upper limit of noise reduction is only 4 dBA. This upper limit can be achieved by changing the design of the brush nozzle. Two methods for noise reduction by enlargement of flow-inlet area and by optimization of the number of blades are tested. Finally, the effects of each method are verified experimentally.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.8
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• pp.693-702
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• 2015

This paper presents the performance characteristics of a Darrieus-type vertical-axis wind turbine (VAWT) with National Advisory Committee for Aeronautics (NACA) airfoil blades. To estimate the optimum shape of the Darrieus-type wind turbine in accordance with various design parameters, we examine the aerodynamic characteristics and separated flow occurring in the vicinity of the blade, the interaction between the flow and blade, and the torque and power characteristics that are derived from it. We consider several parameters (chord length, rotor diameter, pitch angle, and helical angle) to determine the optimum shape design and characteristics of the interaction with the ambient flow. From our results, rotors with high solidity have a high power coefficient in the low tip-speed ratio (TSR) range. On the contrary, in the low TSR range, rotors with low solidity have a high power coefficient. When the pitch angle at which the airfoil is directed inward equals $-2^{\circ}$ and the helical angle equals $0^{\circ}$, the Darrieus-type VAWT generates maximum power.