• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.25-32
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• 2005

The aerodynamic loads at the blade hub and the drive shaft for 1MW horizontal axis wind turbine are calculated numerically. The geometric shape of the blade such as chord length and twist angle can be obtained fran the aerodynamic optimization procedure. Various airfoil data, that is thick airfoils at hub side and thin airfoils at tip side, are distributed along the spanwise direction of the rotor blade. Under the wind data fulfilling design load cases based on the IEC61400-1, all of the shear forces, bending moments at the hub and the low speed shaft of the drive train are obtained by using the FAST code. It shows that shear forces and bending moments have a periodic. trend. These oscillating aerodynamic loads will lead to the fatigue problem at both of the hub and drive train From the load analysis the maximum shear forces and bending moments are generated when wind turbine generator system operates in the case of the extreme speed wind condition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1705-1712
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• 2001

Mechanical component has striation with constant width and SEM can estimate fracture type and loading condition. SEM has benefit to fatigue fracture analysis but striation can be observed according to the kind of material and range of crack growth rate and can't. In this case, it needs AFM that can measure 3-dimensional surface profile with resolution of atomic size. In this study. to find fracture reason of torsion-mounted blade in nuclear plant, we estimate the relation between stress intensity factor range and root mean square roughness in 12% Cr steel by AFM and predict in-service loading condition of turbine blade. failure analysis is performed by finite element method and Goodman diagram on torsion-mounted blade.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.169-175
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• 2000

A design method for transonic turbine blades is developed based on Navier-Stokes equations. The present computing process is done on the four separate steps, 1.e., determination of the blade profile, generation of the computational grids, cascade flow simulation and analysis of the computed results in the sense of the aerodynamic performance. The blade shapes are designed using the cubic polynomials under the control of the design parameters. Numerical methods for the flow equations are based on Van-Leer's FVS with an upwind TVD scheme on the finite volume. Applications are made to the VKI transonic rotor blades. Computed results are analyzed with respect to the aerodynamic performance and are compared with the experimental data.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.16-20
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• 2016

Design optimization of a transonic compressor rotor(NASA rotor 37) was carried out using response surface method(RSM) which is one of the optimization methods. A numerical simulation was conducted using ANSYS CFX by solving three-dimensional Reynolds-averaged Navier Stokes(RANS) equations. Response surfaces that were based on the results of the design of experiment(DOE) techniques were used to find an optimal shape of blade which has the maximum aerodynamic performance. Two objective functions, viz., the adiabatic efficiency and the loss coefficient were selected with three design configurations to optimize the blade shape. As a result, the efficiency of the optimized blade is found to be increased.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1442-1446
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• 2004

The heat (mass) transfer characteristics on the blade surface of a first-stage turbine rotor cascade has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is employed for the measurements of the local heat (mass) transfer coefficient on the curved blade surface. The experiments are carried out for two free-stream turbulence intensities of 1.2% and 14.7%. The high free-stream turbulence results in more uniform distributions of heat load on the both pressure and suction surfaces and in an early boundary-layer separation on the suction surface. The heat (mass) transfer enhancement on the suction surface due to the endwall vortices is found to be relatively small under the high free-stream turbulence.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2440-2443
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• 2008

This paper presents a three dimensional shape optimization procedure for a low-speed axial flow fan blade with a weighted average surrogate model. Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by finite volume approximations. Six variables from airfoil profile and lean are selected as design variables. 3D RANS solver is used to evaluate the objective functions of total pressure efficiency. Surrogate approximation models for optimization have been employed to find the optimal design of fan blade. A search algorithm is used to find the optimal design in the design space from the constructed surrogate models for the objective function. The total pressure efficiency is increased by 0.31% with the weighted average surrogate model.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.307-312
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• 2016

The present study reported of the use of special shaped blade to reduce the difference in pressure across the Wells turbine for wave energy conversion. The blade profile was composed of NACA0020 airfoils and trailing edge was notched like chevron. Experiments were performed investigating the influence of trailing edge shape on the turbine performance. Four notch depths were used to investigate the effect of depth of cut on the turbine performance. As results, by placing a notch-cut at the trailing edge of the blade, it was possible to reduce the pressure difference across the turbine without lowering the efficiency. In addition, the pressure difference substantially reduced at a constant rate with the increase of the cut ratio.

• Wind and Structures
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• v.9 no.6
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• pp.493-503
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• 2006

The demand for energy in the world increases everyday. Blade energy which is wind turbine is a significant resource which must be appreciated in this field. Especially, in places where wind potential is high, the usage of wind energy is a beneficial factor for every country's economy. In this study, first, 6 different miniature rotor were produced by using 6 different NACA profiles. Rotors were produced with three blades. The electrical performance and the speed of start of action values that are provided from each rotor form were established by measuring them in the wind tunnel. The calculation of area and volumetric values of each profile and wind surfaces were made with AutoCad technical drawing program. As a result, it was searched whether there is any relation between electrical performance values and speed of start of motion that rotors produced and volumetric values of rotors. The aim of this study is to find out whether rotor blade volume is one of factors that influences rotor performance. The general tendency observed here is that the increase in the volume of rotor blade leads to an increase in the speed of start of motion and to a decrease in the rotor performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.04a
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• pp.91-94
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• 2001

A structural test of the wind turbine rotor blade must be required to evaluate the uncertainty in design assessment due to use of material, design concepts, production processes and so on, and the possible impact on the structural integrity. In the full-scale static strength test, the measuring parameters are strain, displacements, loads, weight and the center of gravity. There are test equipments, measuring sensors, a test rig and fixtures to obtain measuring parameters. In order to simulate the aerodynamics load, the three-point loading method instead of the one-point loading method is applied. There is slightly some difference between the measured results and the predicted results with the reference fiber volume fraction of 60%. However, the agreement between the measured results and the predicted results with the actual fiber volume fraction of 52.5% is good. Even though a slightly non-linearity from 80% loading to 100% loading, a linear static solution is sufficient for the design purpose as the amount of the non-linearity is relatively small. Comparison between measured and predicted strain results at the maximum thickness positions of the blade profile for 0.236R(5.56m), 0.493R(11.59m) and 0.574R(13.43m), under 20%, 40%, 60%, 80% and 100% loadings for the upper part of the blade. The predicted values are in good agreement with the measured values.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.663-669
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• 2005

Performance characteristics of an axial flow fan having distorted inlet flow have been investigated using numerical analysis as well as experiment. Two kinds of hub-cap, round shape and right-angled front shape, are tested to investigate the effect of inlet flow distortion on the fan performance. In case of right-angled front shape, axisymmetric distorted inflow is induced by flow separation at the sharp edge of hub-cap, and the characteristics of the inflow depends on the distance between hub-cap and blade leading edge. Flow analysis of the blade passage is peformed by solving the three-dimensional Reynolds-averaged Navier-Stokes equations. numerical solutions are validated in comparison with experimental data measured by a five-hole probe downstream of the fan rotor. It is found from the numerical results that non-uniform axial inlet velocity profile near the hub results in the change of inlet flowangle. The changed inlet flow angle near the hub invokesa flow separation on the blade surfaces, thus deteriorating the fan efficiency. The effect of the distance between hub-cap and blade leading edge on the efficiency is also discussed.