• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.39-51
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• 2014

This paper deals with design of a direct-coupled, small-scaled permanent magnet generator (PMG) for wind power application. First, this paper determines rated power and speed of the PMG from measured characteristics of wind turbines. Second, we derive analytical solutions for the open-circuit field in order to determine optimum magnet thickness and pole pitch/arc ratio. Third, on the basis of open circuit field solutions, stator magnetic circuit including slot opening, teeth width and yoke thickness is designed. And then, a diameter of stator coil which agree with a required current density is calculated, and its turns are determined from the area of slot considering winding packing factor. Finally, finite element (FE) method is employed in analyzing the details of the designed PMG and, test results such as back-emf measurements are given to confirm the design.

• Journal of the Korean Society of Visualization
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• v.11 no.1
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• pp.28-33
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• 2013

This paper describes aerodynamic characteristics of an Archimedes spiral wind turbine with various angles of attack. The range of angles was controlled from $-30^{\circ}$ (clockwise) to $+30^{\circ}$ (clockwise). The rotating speed of wind turbine at the same angle of attack in both directions was different. The reason why the-maximum rotational speed was observed at $15^{\circ}$ in clockwise direction can be explained based on angular momentum conservation. Quantitative flow visualization around Archimedes wind turbine blade was carried out between $-15^{\circ}$ (clockwise) and $+15^{\circ}$ (counter clockwise) using high resolution PIV method. The relationship between drag force and rotating speeds was discussed. From these results, optimum design on yawing system of Archimedes spiral wind turbine may provide high efficiency on small wind power system.

• Wind and Structures
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• v.34 no.4
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• pp.355-369
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• 2022

Section model test, as the most commonly used method to evaluate the aerostatic and aeroelastic performances of long-span bridges, may be carried out under different conditions of incoming wind speed, geometric scale and wind tunnel facilities, which may lead to potential Reynolds number (Re) effect, model scaling effect and wind tunnel scale effect, respectively. The Re effect and scale effect on aerostatic force coefficients and aeroelastic characteristics of streamlined bridge decks were investigated via 1:100 and 1:60 scale section model tests. The influence of auxiliary facilities was further investigated by comparative tests between a bare deck section and the deck section with auxiliary facilities. The force measurement results over a Re region from about 1×10⁵ to 4×10⁵ indicate that the drag coefficients of both deck sections show obvious Re effect, while the pitching moment coefficients have weak Re dependence. The lift coefficients of the smaller scale models have more significant Re effect. Comparative tests of different scale models under the same Re number indicate that the static force coefficients have obvious scale effect, which is even more prominent than the Re effect. Additionally, the scale effect induced by lower model length to wind tunnel height ratio may produce static force coefficients with smaller absolute values, which may be less conservative for structural design. The results with respect to flutter stability indicate that the aerodynamic-damping-related flutter derivatives 𝘈^*₂ and 𝐴^*₁𝐻^*₃ have opposite scale effect, which makes the overall scale effect on critical flutter wind speed greatly weakened. The most significant scale effect on critical flutter wind speed occurs at +3° wind angle of attack, which makes the small-scale section models give conservative predictions.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.285-295
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• 2016

A contact strip shape of a high speed train pantograph system was optimized with CFD to increase the aerodynamic performance and stability of contact force, and the results were validated by a wind tunnel test. For design of the optimal contact strip shape, a Kriging model and genetic algorithm were used to ensure the global search of the optimal point and reduce the computational cost. To enhance the performance and robustness of the contact strip for high speed pantograph, the drag coefficient and the fluctuation of the lift coefficient along the angle of attack were selected as design objectives. Aerodynamic forces were measured by a load cell and HWA (Hot Wire Anemometer) was used to measure the Strouhal number of wake flow. PIV (Particle Image Velocimetry) was adopted to visualize the flow fields. The optimized contact strip shape was shown a lower drag with smaller fluctuation of vertical lift force than the general shaped contact strip. And the acoustic noise source strength of the optimized contact strip was also reduced. Finally, the reduction amount of drag and noise was assessed when the optimized contact strip was applied to three dimensional pantograph system.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.123-126
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• 2003

In the present paper, the analysis is on the safe navigation between ships moving each other in restricted waterways under the external force, such as wind or current The numerical simulation of manoeuvring motion was carried out to propose an appropriate safe speed and distance between ships, which is required to avoid marine disasters from the viewpoint of marine safety. From the inspection q this investigation, it indicates the following result In case of proximal navigation between ships under the wind and current, the low-speed vessel is potentially hazardous because the rudder force if low-speed vessel needed for steady-state course-keeping is not sufficient, compared to the high-speed vessel The manoeuvring characteristic based on this investigation will be very useful for keeping the safety of navigation from the practical point of ships design and traffic control in restricted waterways.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.409-413
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• 2007

To assure the structural integrity for the hub and low speed shaft (LSS) of the drive train, it is necessary to obtain the ultimate aerodynamic loads acting on the wind turbine blade. The aim of this study is to predict the time histories of 3 forces and 3 moments at the hub and the LSS based on the design load case of the IEC 61400-1. From the calculated results most of the load components have rotor revolution frequency whereas thrust and torque of the LSS show blade passage frequency. It turns out that the EWM wind condition involves the maximum ultimate loads at both hub and LSS of the horizontal axis wind turbine.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.245-248
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• 2006

The first of korean 750kW gearless type wind turbine is developed. The wind turbine is designed, manufactured and tested by GE regulation and obtained the design certificate by GL. And the performance test is being performed at the demonstration site now. This paper presents the history of development and performance test for 750kW gearless type wind turbine.

• Wind and Structures
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• v.32 no.1
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• pp.47-53
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• 2021

This paper proposes a novel diffuser design for Diffuser Augmented Wind Turbines (DAWT) based on the blunt trailing edge airfoil AF300. Computational Fluid Dynamics (CFD) simulations are carried out to measure the performance of the AF300 diffuser against diffusers made with the shape of other high performance low wind speed airfoils. The results show that the proposed diffuser produces a greater air mass flow increase through the plane of the turbine than the other diffusers and it can be used to increase the performance of a horizontal axis wind turbine.

• Wind and Structures
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• v.34 no.2
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• pp.185-197
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• 2022

This study aimed to analyze the wind-induced mechanical energy (WME) of a proposed super high-rise and long-span transmission tower-line system (SHLTTS), which, in 2021, is the tallest tower-line system with the longest span. Anew index - the WME, accounting for the wind-induced vibration behavior of the whole system rather than the local part, was first proposed. The occurrence of the maximum WME for a transmission tower, with or without conductors, under synoptic winds, was analyzed, and the corresponding formulae were derived based on stochastic vibration theory. Some calculation data, such as the drag coefficient, dynamic parameters, windshielding areas, mass, calculation point coordinates, mode shape and influence function, derived from wind tunnel testing on reducedscale models and finite element software were used in calculating the maximum WME of the transmission tower under three cases. Then, the influence of conductors, wind speed, gradient wind height and wind yaw angle on WME components and the energy transfer relationship between substructures (transmission tower and conductor) were analyzed. The study showed that the presence of conductors increases the WME of transmission towers and changes the proportion of the mean component (MC), background component (BC) and resonant component (RC) for WME; The RC of WME is more susceptible to the wind speed change. Affected by the gradient wind height, the WME components decrease. With the RC decreasing the fastest and the MC decreasing the slowest; The WME reaches the its maximum value at the wind yaw angle of 30°. Due to the influence of three factors, namely: the long span of the conductors, the gradient wind height and the complex geometrical profile, it is important that the tower-line coupling effect, the potential for fatigue damage and the most unfavorable wind yaw angle should be given particular attention in the wind-resistant design of SHLTTSs

• Wind and Structures
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• v.19 no.5
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• pp.541-563
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• 2014

This paper investigates the topographic effects on wind characteristics over hilly terrain, based on wind data recorded at a number of meteorological stations in or near complex terrain. The multiply data sources allow a more detailed investigation of the flow field than is normally possible. Vertical profiles of mean and turbulent wind components from a Sodar profiler were presented and then modeled as functions of height and wind speed. The correlations between longitudinal and vertical wind components were discussed. The phenomena of flow separation and generation of vortices were observed. The distance-dependence of the topographic effects on gust factors was revealed subsequently. Furthermore, the canyon effect was identified and discussed based on the observations of wind at a saddle point between two mountain peaks. This study aims to further understanding of the characteristics of surface wind over rugged terrain. The presented results are expected to be useful for structural design, prevention of pollutant dispersion, and validation of CFD (computational fluid dynamics) models or techniques over complex terrains.