Cheol-Hyun Hong

A Study of the FE Analysis Technique of Hybrid Blades for Large Scale Wind-Turbine

According to recent figures, 35% of the world`s blades are made using prepreg blades, by Vestas and Gamesa. They are the most advanced in the market today. In this study, we investigated the validity of the finite element method (FEM) applied to an FE analysis of a hybrid composite wind-turbine blade. Two methods were suggested for a composite FE analysis: using the equivalent properties of the composite or using stacking properties. FE analysis results using the stacking properties of the composite were in good agreement with results of using the equivalent properties. The difference between FE results was approximately 0.6~13.3%.

Buckling Analysis of Filament-wound Composite Towers for Large Scale Wind-Turbine

*Pusan Educational Center for Computer Aided Machine Design, Pu san National University, Busan, KoreaKEY WORDS: Composite 복합재, Filament-wound 필라멘트 와인딩, Tower 타워, Wind-turbine 풍력, Buckling 좌굴 ABSTRACT: The purpose of this study was to investigate the buckling load of filament-wound composite towers for large scale wind-turbine s using the finite element method (FEM). To define the material p roperties, we used both the effective property method and stack ing properties method. The effective properties method assumes that a composit e consists of one ply. The stacking properties method assumes t hat a composite consists of several stacked plies. First, a linear buckling ana lysis of the tower, filament-wound with angles of [ ±30], was carried out using the two methods for composite material properties: the stacking method and effective method. An FE analysis was also performed for the composite towers using the filament winding angles of [±30], [±45], and [±60]. The FE analysis results using the stacking properties of t he composite were in good agreement with the results from the effective properties method . The difference between the FEM results and material propertie s method was approximately 0~2.3%. Above the angle of [±60], there was little change in the buckling load.교신저자 홍철현: 부산광역시 금정구 장전동 산30번지, 051-510-1665, chhong@pusan.ac.kr

Performance improvement of airfoils for wind blade with the groove

ABSTRACT This study was a basic one to explore how much the aerodynamic characteristics of wind blade improve. The extent of improvement according to the shapes of groove placed on the surface of airfoil (NACA0015) was analyzed through computational analysis. A commercial computational fluid dynamics (CFD) code, the ANSYS Fluent 13, was used in this study. In this study, regarding with the positions and shapes of groove, the end of groove was placed at a certain distance (length, l) from both the front and back of separation starting point, the depth and the width were designated as h and d respectively. Analysis was conducted at the 7° angle of attack under the following conditions; the thickness (δ) of boundary layer to the depth (h) of groove ratio (h/δ) 0.6–1.0, the depth (h) of groove to the width (d) of groove ratio (h/d) 0.1–1.4, and the length (l) between the end of groove and separation point to the thickness (δ) of boundary layer ratio (l/δ) −0.5–0.5. Among these conditions, the best improvement of lift to drag ratio, standing at 15.3%, was under h/δ = 1.0, h/d = 0.12, and l/δ = –0.5 (7° AOA, Re = 360k). In addition, throughout the range of angle of attack, 2–14°, lift to drag ratio improved by 0.8%, 5.1%, 3.2%, and 1.8% each when Reynolds numbers were 280k, 360k, 450k, and 530k. It is also confirmed that the shape of groove contributed to recovering velocity around airfoil wall and the lift to drag ratio improvements by groove were maintained at the given range of Reynolds number and around the angle of attack, 7°.

Basic Experiment Using Taguchi method for Vertical Wind Turbine with Wind-shield

This study aimed to develop a wind turbine system for the domestic wind environments. The Taguchi method was applied to obtain the optimal design for a wind turbine with a wind-shield. The design parameters were defined to look for the shape of the wind turbine. Optimal parameters were determined on the basis of the analyzed level averages of the characteristics. According to the test results to which the optimal parameters were applied, the rpm improved. It was also found that a windshield 3/4 the size contributes to improving the efficiency of existing turbines.

A Study on Development and Analysis for Wind Turbine Blades Using Composites Materials

ABSTRACT Wind turbine blades will be required to be longer, lighter, more reliable and more consistent. Therefore it is necessary to lose weight of the wind turbine blades. This points squarely toward prepreg blade production growing. It is important to note however that prepreg blade production as it is today is flawed and that there are ways to improve greatly on the performance of these blades in manufacturing process and in their in-service performance. Through this, we have some detail on the current process and its advantage of cost and weight of blades. †† 1. 서 론 새로운 복합재료는 재료의 효율적인 조합에 의하여 구조물의 중량감소와 피로하중에 대한 높은 내구성, 안정성, 내열성 등의 이유로 해양구조물 (1) , 항공우주 (2) 부품 등에 사용되어 왔다. 최근에는 신재생에너지 분야의 풍력발전시스템과 같은 첨단 신소재산업에 적용되어 미래 유망 거대산업으로 각광받고 있는 실정이다. 이러한 복합재료는 응용범위가 넓고, 선도적 기술혁신을 통한 타 산업으로 연계 파급효과가 매우 클 뿐만 아니라 기술적 우위를 확보하기가 어려운 대형 산업이다 (3) .풍력발전시스템에서 블레이드는 바람이 가진 에너지를 회전력으로 변환시켜 주는 회전익으로 가장 중요한 요소이며, 풍력발전기의 대형화 추세 속에 경제성과 신뢰성을 높이는 것이 가장 큰 관건이라 할 수 있다. 이에 풍력발전시스템의 블레이드에 사용되는 복합재료는 몇몇 선진국에 한해 개발된 상태이고, 이의 제조 및 응용기술은 각 나라마다 국가적인 차원에서 보호하는 실정이어서 일부 업체들에 의하여 독* (주)도하인더스트리 기술연구소** 부산대학교 기계설계전산화인력양성센터***군산대학교 조선공학과† 교신저자, E-mail : moonby20@gmail.com점 생산 및 고가로 판매되고 있다.따라서 본 논문에서는 국외 선진 풍력발전시스템 블레이드 개발업체에서 적용되고 있는 프리프레그(Prepreg) 공법을 소개하고 내구성, 안정성 및 비용적인 측면에서 제품 경쟁력 등을 보고하고자 한다. 그리고 유한요소해석을 이용하여 복합재 블레이드의 고유진동수를 수행하였다.