• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.521-524
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• 2009

This study describes aerodynamic noise of high speed wind turbine system, which is invented as a new concept in order to reduce the torque of main shaft, for design parameters of the rotor blade. For parametric study of high speed rotor aerodynamic noise, Unsteady Vortex Lattice Method with Nonlinear Vortex Correction Method is used for analysis of wind turbine blade aerodynamic and Farassat1A and Semi-Empirical are used for low frequency noise and airfoil self noise. Parameters are chord length, twist and rotational speed for this parametric research. In the low frequency range, the change of noise is predicted the same level as each parameters varies. However, in case of broadband noise of blade, the change of rotational speed makes more variation of noise than other parameters. When the geometric angles of attack are fixed, as the rotational speed is increased by 5RPM, the noise level is increased by 4dB.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.861-866
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• 2004

A numerical flow analysis has been performed on the partial admission turbine of KARI turbopump to support the aerodynamic and structural dynamic assessments. The flow-field in a partial admission turbine is essentially three dimensional and unsteady because of a tip clearance and a finite number of nozzles. Therefore the mixing plane method is generally not appropriate. To avoid heavy computational load due to an unsteady three dimensional calculation, a frozen rotor method was implemented in steady calculation. It adopted a rotating frame in the grid block of a rotor blade by adding some source terms in governing equations. Its results were compared with a mixing plane method. The frozen rotor method can detect the variation of flow-field dependent upon the blade's circumferential position relative to the nozzle. It gives a idea of wake loss mechanism starting from the lip of a nozzle. This wake loss was assumed to be one of the most difficult issues in turbine designers. Thus, the frozen rotor approach has proven to be an efficient and robust tool in design of a partial admission turbine.

• 풍력에너지저널
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• 제2권1호
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• pp.61-67
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• 2011

In the present study, numerical unsteady simulations of the NREL Phase VI wind turbine in downwind operation conditions were conducted to investigate rotor-tower interaction. The calculations were performed using an unstructured mesh, incompressible Reynolds-averaged Navier-Stokes flow solver. To capture the unsteady effects associated with the tower shadow between the rotor blades and the tower, the wind turbine was modelled including the rotor, tower, hub, and nacelle. The present results generally showed good agreements with available experimental data. At the lowest wind speed, the pressure distribution was characterized by a complete collapse of the suction peak on the blade when the blade passes through the tower wake. It was found that unsteady effects play a significant role in the response of the blades.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.456-465
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• 2016

In order to optimize the performance of a Wells turbine with fixed guide vanes, the designs of an end plate and a ring on the tip of the turbine rotor are proposed as penetrating blade tip treatments. In this study, numerical investigations are made using computational fluid dynamics (CFD)-based ANSYS Fluent software, and validated by corresponding experimental data. The flow fields are analyzed and non-dimensional coefficients $C_A$, $C_T$ and ${\eta}$ are calculated under steady-state conditions. Numerical results show that the stalling phenomenon on a ring-type Wells turbine occurs at a flow coefficient of ${\phi}=0.36$, and its peak efficiency can reach 0.54, which is 16% higher than that of an unmodified turbine and 9% higher than in the case of an endplate-type turbine. In addition, quasi-steady analysis is used to calculate the mean efficiency and output work of a wave cycle under sinusoidal flow conditions. As a result, it has been found that the ring-type turbine is superior to other types of Wells turbines.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.453-460
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• 2000

A test rig is developed for performance test of 1 stage axial-type turbine which is designed by meanline analysis, streamline curvature method, and blade design method using configuration parameters. The purpose of this study is to find the best configuration parameters for designing a high efficiency axial-type turbine blade. To measure the efficiency of turbine stage, a dynamo-meter is installed. Two different stators which are manufactured as an integrated type are developed, and a rotor blade and 5 sets disc are developed for setting different stagger angle. The tip and hub diameters of the test turbine are 300 and 206.4mm, respectively. The rotating speed is 1800RPM, and the extracted power is 2.5kW. Flow coefficient is 1.68 and the reaction factor at meanline is 0.373. The number of stator and rotor of test turbine are 31 and 41, respectively. The Mach number of stator exit flow near hub is 0.164.

• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.157-166
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• 2016

Aerodynamic loads for a horizontal axis wind turbine of the National Renewable Energy Laboratory (NREL) Phase VI rotor in yawed condition were predicted by using the blade element momentum theorem. The classical blade element momentum theorem was complemented by several aerodynamic corrections and models including the Pitt and Peters' yaw correction, Buhl's wake correction, Prandtl's tip loss model, Du and Selig's three-dimensional (3-D) stall delay model, etc. Changes of the aerodynamic loads according to the azimuth angle acting on the span-wise location of the NREL Phase VI blade were compared with the experimental data with various yaw angles and inflow speeds. The computational flow chart for the classical blade element momentum theorem was adequately modified to accurately calculate the combined functions of additional corrections and models stated above. A successive under-relaxation technique was developed and applied to prevent possible failure during the iteration process. Changes of the angle of attack according to the azimuth angle at the specified radial location of the blade were also obtained. The proposed numerical procedure was verified, and the predicted data of aerodynamic loads for the NREL Phase VI rotor bears an extremely close resemblance to those of the experimental data.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1038-1044
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• 2017

액체 로켓 엔진의 터보펌프를 구동하는 고압 초음속 충동형 터빈의 로터 블레이드에 3차원 설계 요소를 적용하여 성능을 개선하기 위한 연구를 진행하고 있다. 본 논문에서는 기존 설계된 터보펌프용 터빈의 로터 블레이드 형상을 바탕으로 로터 블레이드에 스윕(sweep)과 상반각(dihedral) 등과 같은 중첩선(stacking line) 변화를 통한 3차원 형상을 적용하고 CFD를 이용한 3차원 유동 해석을 수행한 후, 각각의 설계 요소에 대한 터빈성능 특성 변화를 면밀히 검토하고 그 결과를 정리하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.119-124
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• 2004

In this study, a rotor blade of a Curtis turbine is investigated. Bezier curve is generally used to define the profile of turbine blades. However, this curve gives a feature of global control, which is not proper to a supersonic impulse turbine blade. Thus, a blade design method is developed by using B-spline curve so that local control is possible to obtain an optimized blade section. To design a Curtis turbine blade section systematically, the blade section has been changed by varying three design parameters using central composite design method. Flow analyses have been carried out for the blade sections, and the effects of design parameters are evaluated.

• 동력기계공학회지
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• 제5권3호
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• pp.38-47
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• 2001

One stage axial type turbine is designed by mean-line analysis, streamline curvature method and blade design method using shape parameters. Tip and hub diameter of the turbine are 300mm and 206.4mm, respectively. The rotating speed is 1800RPM, and the output power is 1.4kW. The flow coefficient is 1.68 and the reaction factor at mean-line is 0.373. The number of stator and rotor of the turbine are 31 and 41, respectively. Mach number of stator exit flow near hub is 0.164. A test rig is developed for performance test to validate a developed design method. The experimental result shows that the maximum efficiency is obtained on the design point.

• 한국유체기계학회 논문집
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• 제15권2호
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• pp.63-68
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• 2012

This paper deals with the aerodynamic analysis and structural test under estimated loading condition for small composite blade, which is utilized in dual rotor wind turbine system. Firstly, the front and rear blades of dual rotor wind turbine system were modeled using reverse engineering method. And using finite volume method, the aerodynamic forces were analyzed at the rated and cutout wind speed to identify the pressure distribution on blades. And then, the full scale structural tests were conducted according to load and strength based methodology in IEC 61400-2 to identify the structural integrity of composite blade.