• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.10a
• /
• pp.764-765
• /
• 2012

• Wind and Structures
• /
• v.20 no.6
• /
• pp.751-761
• /
• 2015

A multi-platform offshore wind farm is receiving the worldwide attention for the sake of maximizing the wind power capacity and the dynamic stability at sea. But, its wind power efficiency is inherently affected by the interference of wake disturbed by the rotating blades, so its layout should be appropriately designed to minimize such wake interference. In this context, the purpose of this paper is to introduce a layout optimization for multi-platform offshore wind farm consisted of 2.5MW spar-type floating wind turbines. The layout is characterized by the arrangement type of wind turbines, the spacing between wind turbines and the orientation of wind farm to the wind direction, but the current study is concerned with the spacing for a square-type wind farm oriented with the specific angle. The design variable and the objective function are defined by the platform length and the total material volume of the wind farm. The maximum torque loss and overlapping section area are taken as the constraints, and their meta-models expressed in terms of the design variable are approximated using the existing experimental data and the geometry interpretation of wake flow.

• International Journal of Aerospace System Engineering
• /
• v.10 no.2
• /
• pp.1-4
• /
• 2023

Even though the recent development trend of wind turbine systems has been focused on larger MW Classes, the small-scale wind turbine system has been continuously developed because it has some advantages due to easy personnel establishment and use with low cost and energy saving effect. This work is to propose a specific structural design and analysis procedure for development of a low noise 500W class small wind turbine system which will be applicable to relatively low wind speed region like Korea. The proposed structural feature has a skin-spar-foam sandwich composite structure with the E-glass/Epoxy face sheets and the Urethane foam core for lightness, structural stability, low manufacturing cost and easy manufacturing process. Moreover this type of structure has good behaviors for reduction of vibration and noise. Structural analysis including load cases, stress, deformation, buckling and vibration was performed using the Finite Element Method. In order to evaluate the designed blade structure the structural tests were done, and their test results were compared with the estimated results.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.10a
• /
• pp.174-178
• /
• 2001

본 논문에서는 여러 가지 실린더형 스파 부이의 안정성을 평가하고, shear force를 보강하고 votex를 줄이기 위한 나선형판의 형태와 크기가 운동에 어떤 영향을 미치는지를 조사하였다. 그 결과 나선형판의 운동진폭에 미치는 영향은 극히 작은 것으로 안정성을 향상시키기 위해서는 형상의 변화가 더욱 중요함을 알수 있었다.

• Journal of Wind Energy
• /
• v.14 no.2
• /
• pp.14-25
• /
• 2023

This study focuses on proposing measures for the reasonable development of offshore wind farms using the case of Norway, which was the first nation in the world to build a floating offshore wind farm of 80 MW or more. Norwegian authorities conducted a strategic environment assessment in 2012 to select offshore wind farm sites, discovered 15 potential sites, and finally decided on two designated sites in 2020. Based on various survey data such as seabirds, marine environment, and fishing activities, scientific-based spatial analysis was conducted to select additional offshore wind farm sites in line with future development plans. In addition, a government-led steering committee and advisory group have established marine spatial plans since 2002. Therefore, it will be possible to listen to and coordinate the opinions of stakeholders by using the steering committee and advisory group for offshore wind power development. By examining the case of Norway, we suggest the following policy points that can achieve carbon neutrality and develop sustainable offshore wind farms: 1. Establish a government-led steering committee and advisory group that can select potential sites for offshore wind farms by coordinating the opinions of stakeholders 2. Induce efficient and sequential offshore wind farm development by using various survey data and scientific-based spatial analysis.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.1
• /
• pp.9-20
• /
• 2018

Due to integrated stochastic wind and wave loads, the supporting platform of a Floating Offshore Wind Turbine (FOWT) has to bear six Degrees of Freedom (DOF) motion, which makes the random cyclic loads acting on the structural components, for instance the tower base, more complicated than those on bottom-fixed or land-based wind turbines. These cyclic loads may cause unexpected fatigue damages on a FOWT. This paper presents a study on short-term fatigue damage at the tower base of a 5 MW FOWT with a spar-type platform. Fully coupled time-domain simulations code FAST is used and realistic environment conditions are considered to obtain the loads and structural stresses at the tower base. Then the cumulative fatigue damage is calculated based on rainflow counting method and Miner's rule. Moreover, the effects of the simulation length, the wind-wave misalignment, the wind-only condition and the wave-only condition on the fatigue damage are investigated. It is found that the wind and wave induced loads affect the tower base's axial stress separately and in a decoupled way, and the wave-induced fatigue damage is greater than that induced by the wind loads. Under the environment conditions with rated wind speed, the tower base experiences the highest fatigue damage when the joint probability of the wind and wave is included in the calculation. Moreover, it is also found that 1 h simulation length is sufficient to give an appropriate fatigue damage estimated life for FOWT.

• Aerospace Engineering and Technology
• /
• v.12 no.2
• /
• pp.209-220
• /
• 2013

The process of designing and building a human-powered aircraft (HPA) and its performance analysis are introduced in this paper. Light Bros, the Chungnam National University HPA team, has developed Volante, a HPA, to compete in the 2012 exhibition of human-powered aircraft hosted by Korea Aerospace Research Institute. The power train system is composed of a two-blade propeller and Bevel-type gear and the ground test bed is built to simulate the operation. A study has been made to find a efficient propeller based upon the test result of thrust and power available from a pilot under various propeller conditions and running time. The load and structural analysis is conducted for the glider-shaped wing made of composite material which has very high aspect ratio. The spar is analyzed using finite element modeling followed by the comparison of its displacement and strain on structural test. As a result, the performance and safety is confirmed.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2005.11a
• /
• pp.190-193
• /
• 2005

The purpose of the present study is to design a 500W-class micro scale composite wind turbine blade. The blade airfoil of FFA-W3-211 was selected to meet Korean weather condition. The skin-spar-f Dam sandwich type structure was adopted for improving buckling and vibration damping characteristics. The design loads were determined at wind speed of 25m/s. and the structural analysis was performed to confirm safety and stability from strength. buckling and natural frequency using the finite element code. NISA II [6]. The prototype was manufactured using the hand-lay up method and it was experimently tested using the sand bag loading method. In order to evaluate the design results. it was compared with experimental results. According to comparison results. the estimated results such as compressible stress. max tip deflection natural frequency and buckling load factor were well agreed with the experimental results.

• Journal of Aerospace System Engineering
• /
• v.1 no.1
• /
• pp.36-44
• /
• 2007

This study was performed on preliminary structural design of a small scale WIG craft which has been developed as a next generation high speed maritime transportation system in Korea. A composite structure design using the foam-sandwich for main wing and tail fins and the honeycomb sandwich and skin-stringer-ring frame for fuselage was applied for weight reduction as well as structural stability. A commercial FEM code, NASTRAN for was utilized to confirm the structural safety for the reiterate design modifications to meet design requirements including the target weight. Each main wing was jointed with the fuselage by eight high strength insert bolts for easy assembling and disassembling as well as for assuring the required 20 years service life. For control surface structural design, the channel type spar, the foam sandwich skin and the lug joint were adopted.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.349-352
• /
• 2007

A GFRP based composite blade was developed for a 2MW wind energy conversion system of type class IIA. The blade sectional geometry was designed to have a general shell-spar and shear web structure. The load cases specified in the IEC61400-1 international specification were considered. For withstanding all relevant extreme loads, the structural analysis for the complete blade was performed using a commercial FEM code. The static load carrying capacity, blade tip deflection and natural frequencies were evaluated to satisfy the strength and stability requirements in accordance with the IEC61400-1 and GL Regulations. The prototype blade was passed the structural proof test for GL certification.