• 한국유체기계학회 논문집
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• 제17권3호
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• pp.46-51
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• 2014

In this study, a numerical analysis methodology is studied to predict thermal and flow characteristics of C3X vane with internal cooling. Effects of turbulence models, transition models and viscous work term on temperature and pressure distributions on the vane surface are investigated. These optional terms have few effects on the pressure distributions over the vane surface. However, they have great influence on prediction of the temperature distributions on the vane surface. The combination of k-${\omega}$ based SST turbulence model, ${\gamma}$ transition model and viscous work term are better than RSM turbulence model on prediction of the surface temperature. The average temperature difference between CFD results and experimental results is calculated 2 % at the pressure side and 1 % at the suction side. Furthermore computing time of this combination is half of the RSM turbulence model. When k-${\omega}$ based SST turbulence model and ${\gamma}$ transition model with viscous work term are applied, more accurate predictions of thermal and internal flow characteristics of high pressure turbine are expected.

• 대한기계학회논문집B
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• 제41권8호
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• pp.521-529
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• 2017

본 연구에서는 항공기 추진용 가스터빈 엔진의 고증속 터빈 제1단 정익 익렬을 새로이 구축하고, 이 정익의 기본 유동 특성에 대하여 연구하였다. 그 결과 본 연구에서 도입된 정익의 압력면에는 강한 순압력구배가 존재하는 반면, 흡입면에는 앞전에서 미드코드 근처까지 압력면보다 훨씬 더 심한 순압력구배가 존재하고 그 이후 역압력구배가 존재하였다. 두 종류의 유막법을 적용한 유동의 가시화 실험을 통하여, 정익 앞전 상류 영역에 4와류모델 말발굽와류 시스템이 존재함을 확인하였고, 입구 경계층 유동의 박리선과 재부착 유동의 박리선을 정확히 파악하였다. 이와 함께 이 고증속 정익 익렬 하류에서의 2차유동, 압력손실, 선회각, 등에 대한 데이터를 확보하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제29권7호
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• pp.750-757
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• 2005

The objective of this study is an understanding of the effect of inlet flow angle on the output power performance of a Francis hydraulic turbine, An optimum induced angle at the inlet of the turbine is one of the most important design parameters to have the best performance of the turbine at a given operating condition, In general. rotating speed of the turbine is varied with the change of water mass flowrate in a volute, The induced angle of the inlet water should be properly adjusted to the operating condition to have maximum energy conversion efficiency of the turbine, In this study. a numerical simulation was conducted to have detail understanding of the flow phenomenon in the flow path and output power of the model Francis turbine. The indicated power produced by the model turbine at a given operating condition was found numerically and compared to the brake power of the turbine measured by experiment at KIER. From comparison of two results, turbine efficiency or energy conversion efficiency of the model turbine was estimated. From the study, it was found that the rotating power of the turbine linearly increased with the rotating speed. It means that the higher volume flow rate supplied. the bigger torque on the turbine shaft generated. The maximum brake efficiency of the turbine is around 46$\%$ at 35 degree of induced angle. The difference between numerical and experimental output of the model turbine is defined as mechanical efficiency. The maximum mechanical efficiency of the turbine is around 93$\%$ at 25$\∼$30 degree of induced angle.

• 대한조선학회논문집
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• 제50권4호
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• pp.248-254
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• 2013

In this paper, we establish an analysis algorithm and a design procedure for a Vane-Wheel which is a freely rotating device behind a propeller, by using a panel method. Vane-Wheel's function is to extract energy from the propeller slipstream in turbine part which is inner part of the Vane-Wheel, and convert this energy into an additional propulsive thrust in propeller part which is outer part of the Vane-Wheel. Two parts must satisfy torque balance and thrust has to act to the ship's forward direction. A Vane-Wheel has large interaction effect with propeller since it is placed behind of the propeller. Therefore, in order to consider interaction effect correctly, incoming velocity to the Vane-Wheel in a circumferential mean wake was calculated considering induced velocity from propeller to the Vane-Wheel. Likewise, incoming velocity to the propeller was calculated considering induced velocity from the Vane-Wheel to the propeller. This process is repeated until a converged result is obtained.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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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.

• 한국유체기계학회 논문집
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• 제18권5호
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• pp.19-25
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• 2015

As a core component of a hydropower station, hydro turbines play a vital role in the integration of a power station. Research on the technology of hydro turbine is continuously increasing with the development of water electricity. On the basis of one-dimensional loss analysis, for three-dimension design, there are a lot of dimension of the internal flow passage shapes that are determined by experience. Therefore, the effect of the internal flow passage shapes on the performance and internal flow characteristics of a Francis hydro turbine model is investigated in this study. In this study, the small curvature of runner blade trailing edge shape is good for improving the efficiency of Francis turbine. The straight stay vane leading edge is good for suppressing the secondary flow. Moreover, suitable tongue passage shape and stay vane number improve the performance of the turbine considerably.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2839-2844
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• 2007

Micro hydraulic power generation of which the output is less or equal to a 100kW is attracting considerable attention. This is because of its small, simple, renewable, and abundant energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Moreover influences of pressure and velocity distributions with the variations of runner vane angle on turbine performance are investigated by using a commercial CFD code.

• International Journal of Fluid Machinery and Systems
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• 제10권2호
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• pp.154-163
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• 2017

Performance characteristics in pump mode of pump-turbines are vital for the safe and effective operation of pumped storage power plants. However, the head characteristics are different under different guide vane openings. In this paper, 3-D steady simulations were performed under 13mm, 19mm and 25mm guide vane openings. Three groups of operating points under the three GVOs were chosen based on experimental validation to investigate the influence of guide vane setting on flow patterns upstream and downstream. The results reveal that, the guide vane setting will obviously change the flow pattern downstream, which in turn influences the flow upstream. It shows a strong effect on hydraulic loss (power dissipation) in the guide and stay vanes. It is also found that the hydraulic loss mainly comes from the flow separation and vortices. In addition, in some operating conditions, the change of guide vane opening will change the flow angle at the runner inlet and outlet, which will change the Euler momentum (power input). The joint action of Euler momentum and hydraulic loss results in the change of the head characteristics.

• Coupled systems mechanics
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• 제7권4호
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• pp.421-440
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• 2018

In this study, a computational method for wall shear stress combined with an implicit direct-forcing immersed boundary method is presented. Near the immersed boundaries, the sub-grid stress is determined by a wall model in which the wall shear stress is directly calculated from the Lagrangian force on the immersed boundary. A coupling mathematical model of the transition process for a model Francis turbine comprising turbulent flow and rotating rigid guide vanes is established. The spatiotemporal distributions of pressure, velocity, vorticity and turbulent quantity are gained with the transient process; the drag and lift coefficients as well as other forces (moments) are also obtained as functions of the attack angle. At the same time, analysis is conducted of the characteristics of pressure pulsation, velocity stripes and vortex structure at some key parts of flowing passage. The coupling relations among the turbulent flow, the dynamical force (moment) response of blade and the rotating of guide vane are also obtained.

• 한국태양에너지학회 논문집
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• 제21권1호
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• pp.27-31
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• 2001

The Kaplan turbine model has been tested and analized. 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 hydro power stations with large changes in head and load.