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- 2015
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이 논문의 연구 히스토리 (5)
2015
친환경 섬유 적용 소형 블레이드 구조 시험
박광림
,
공창덕
,
이상규
외 3명
항공우주시스템공학회 학술행사 논문집
2015.11
학술대회자료
친환경 아마 섬유를 적용한 소형 풍력 발전 블레이드 공력 및 구조 설계 연구
박광림
,
공창덕
,
박길수
외 1명
항공우주시스템공학회 학술행사 논문집
2015.05
학술대회자료
친환경 소재를 적용한 500W급 고효율 수평축 풍력터빈 블레이드 설계에 관한 연구
박광림
항공우주공
2015.01
학위논문
친환경 소재를 적용한 500W급 고효율 수평축 풍력터빈 블레이드 설계에관한 연구
박광림
,
공창덕
,
이하승
외 1명
Composites Research
2015.01
학술저널
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초록· 키워드
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Recently due to increasing interest in eco-friendly materials, studies on eco-friendly fiber obtained from nature have been actively conducted to the area of composite. Although the natural fiber has less strength than the high strength fiber such as the carbon fiber, it has similar strength to glass fiber. Accordingly ,it can be applied as very advantageous composite when an appropriate resin has been selected.
The wind turbine system is the cheapest technology which uses one of new and reusable energy resources, although it has a disadvantage of low efficiency of the system and little quantity of power generation because it is totally dependant upon wind resource.
Because the output of the generation system become larger in proportion to the square of the diameter, generators in the MW class is used sometimes, but it has a restriction of cost and location; it needs a great amount of investment and vast place to be located. In contrast, the small sized wind turbine system, which is the lower class than the kW class, requires just a individual installation with low cost, and it occupies only a small space.
However, the small sized system that is made and sold by other countries is not effective enough, because, to operate properly, it needs an appropriate wind velocity; more that 12 m/s, but this condition will not be satisfied with our environment. And we have also a situation of exceeding the limit of velocity levels. A typhoon is a good example of it; it is more than 50 m/s in summer. This is why we need our own effective and safe blades for power generation.
As composites resources are used, the blades have achievement in structural intensity, hardness, durability, and cost. There are many kinds of the composites resources: glass/epoxy, carbon/epoxy, wood/epoxy, etc., but the glass/epoxy is mostly used because it is cheap, light, and it has a great performance.
This study evaluates mechanical properties of natural fiber composites. Finally the flax is selected as a natural fiber due to higher strength and better mechanical behaviors than other natural fibers, and the vinyl ester is selected as a resin due to lower cost, easier procurement and better treatment for the resin injection. For easy and fast production of the complicated configuration structure, the resin infusion molding (RIM) manufacturing method is selected.
After investigation on mechanical proper-ties of flax/vinyl ester composite, the design of eco-friendly structure using flax/vinyl ester was performed. This composite is used for the proposed wind turbine blade in this study.
A structural design of 500W class horizontal axis wind turbine blade using natural-fiber composite was performed using both the netting rule and the rule of mixture. The proposed structural type is the skin-spar-foam sandwich, and the aerodynamic configuration that has been designed by the previous work of S. Choi[15] is used for this work. The structural design result of flax fabric composite blade is compared with the result of glass fabric composite blade designed by Choi’s work.
The structural safety of the designed blade structure was investigated through the various load cases, stress, deformation, natural frequency and buckling analyses using the commercial FEM(Finite Elements Method) code, MSC. NASTRAN. In addition, when blade was manufactured using the RIM(Resin Infusion Molding) method under 1 bar vacuum pressure due to better production efficiency and lower defect rate than the hand lay-up process method. Before applying the RIM process to manufacture the blade, the resin flow simulation was carried out to predict the manufacturing possibility using Poly-worx software. The predicted resin filling time was well agreed with the measured filling time during the RIM process.
The structural test of the manufactured prototype blade was performed to confirmed the structural analysis results including strains, natural frequencies and deformations. According to the comparison results, it was confirmed that the analysis results are well agreed with the experimental results.
The wind turbine system is the cheapest technology which uses one of new and reusable energy resources, although it has a disadvantage of low efficiency of the system and little quantity of power generation because it is totally dependant upon wind resource.
Because the output of the generation system become larger in proportion to the square of the diameter, generators in the MW class is used sometimes, but it has a restriction of cost and location; it needs a great amount of investment and vast place to be located. In contrast, the small sized wind turbine system, which is the lower class than the kW class, requires just a individual installation with low cost, and it occupies only a small space.
However, the small sized system that is made and sold by other countries is not effective enough, because, to operate properly, it needs an appropriate wind velocity; more that 12 m/s, but this condition will not be satisfied with our environment. And we have also a situation of exceeding the limit of velocity levels. A typhoon is a good example of it; it is more than 50 m/s in summer. This is why we need our own effective and safe blades for power generation.
As composites resources are used, the blades have achievement in structural intensity, hardness, durability, and cost. There are many kinds of the composites resources: glass/epoxy, carbon/epoxy, wood/epoxy, etc., but the glass/epoxy is mostly used because it is cheap, light, and it has a great performance.
This study evaluates mechanical properties of natural fiber composites. Finally the flax is selected as a natural fiber due to higher strength and better mechanical behaviors than other natural fibers, and the vinyl ester is selected as a resin due to lower cost, easier procurement and better treatment for the resin injection. For easy and fast production of the complicated configuration structure, the resin infusion molding (RIM) manufacturing method is selected.
After investigation on mechanical proper-ties of flax/vinyl ester composite, the design of eco-friendly structure using flax/vinyl ester was performed. This composite is used for the proposed wind turbine blade in this study.
A structural design of 500W class horizontal axis wind turbine blade using natural-fiber composite was performed using both the netting rule and the rule of mixture. The proposed structural type is the skin-spar-foam sandwich, and the aerodynamic configuration that has been designed by the previous work of S. Choi[15] is used for this work. The structural design result of flax fabric composite blade is compared with the result of glass fabric composite blade designed by Choi’s work.
The structural safety of the designed blade structure was investigated through the various load cases, stress, deformation, natural frequency and buckling analyses using the commercial FEM(Finite Elements Method) code, MSC. NASTRAN. In addition, when blade was manufactured using the RIM(Resin Infusion Molding) method under 1 bar vacuum pressure due to better production efficiency and lower defect rate than the hand lay-up process method. Before applying the RIM process to manufacture the blade, the resin flow simulation was carried out to predict the manufacturing possibility using Poly-worx software. The predicted resin filling time was well agreed with the measured filling time during the RIM process.
The structural test of the manufactured prototype blade was performed to confirmed the structural analysis results including strains, natural frequencies and deformations. According to the comparison results, it was confirmed that the analysis results are well agreed with the experimental results.
목차
LIST OF FIGURES ............................................................................................................ iiiLIST OF TABLES ............................................................................................................ vNOMENCLATURE ........................................................................................................... viiiABSTRACT ........................................................................................................................... x제 1 장 서 론 .............................................................................................................. 1제 2 장 설 계 개 요 ........................................................................................................ 3제1절 설계 및 해석 절차 ......................................................................................... 3제2절 설계 요구 조건 .......................................................................................... 4제 3 장 공력 설계 및 성능 해석 .................................................................................. 5제1절 블레이드 공력설계 ................................................................................ 51.공력 설계 절차 및 방법 ................................................................... 5가. 설계초기자료 입력 .......................................................... 5나. 축 방향 속도비와 선회속도비의 계산 ...................................... 5다. 깃 각 결정 .....................................................................·6라. 시위길이 결정 ......................................................... 62.공력 설계 변수 분석 및 최적화 .............................................. 6가. 에어포일의 특성 ......................................................... 6나. 블레이드 직경 ......................................................... 7다. 시위 및 깃 각 설계 방법 ......................................................... 8라. 깃 끝 속도비 ......................................................... 83.공력 설계 결과 ......................................................... 8제2절 공력 성능 해석 ......................................................... 101.공력 해석 절차 및 방법 ......................................................... 10가. 공력 설계 결과 입력 ........................................................ 10나. 단면 에어포일의 받음각 결정 ......................................................· 10다. 블레이드의 출력 계산 ............................................................... 102.공력 해석 결과 ............................................................. 11제 4 장 자연섬유 복합재료 분석 .................................................................................. 13제1절 자연섬유 및 수지 종류 ............................................................................. 13제2절 자연섬유와 수지 선정 .................................................................................. 14제2절 Flax fabric/ Vinyl ester 기계적 물성치 연구 결과 .............................. 15제 5 장 블레이드 구조설계 .................................................................................. 17제1절 하중조건 및 하중계산 .................................................................................... 171. 굽힘 하중 계산 ..................................................................................... 17가. 정상 작동 시 돌풍에 의한 굽힘 하중 ................................................. 18나. 정지 시 폭풍에 의한 굽힘 하중 ....................................................... 20다. 하중 해석 결과 ......................................................................... 21제2절 기본구조단면 형상설계 .................................................................................. 23제3절 구 조 해 석 ...................................................................................................... 251. 구조해석 결과 (Glass/Epoxy 복합재 경우) ......................................... 252. 구조해석 (Flax fabric/vinyl ester 복합재 경우) ....................................... 263. 고유진동수 해석 및 공진 가능성 검토 ...................................................... 284. 좌 굴 해 석 ......................................................................................................... 305. 구조 해석 결과 검토 ........................................................................................ 30제 6 장 제작공법 및 수지 침투 해석 ...................................................... 32제1절 RIM(Resin Infusion Molding) 제작공법 .................................................... 32제2절 Poly-Worx 수지 침투 모사 전산프로그램 ................................................. 33제3절 수지 침투 해석조건 ................................................................................... 34제4절 해석결과 및 검토 ............................................................................................ 36제 7 장 시제품 제작 및 시험 ........................................................................................ 38제1절 시제품 제작 ...................................................................................................... 38제2절 구 조 시 험 ...................................................................................................... 481. 고유 진동수 측정 시험 .............................................................................. 482. 정 하중 구조시험 ............................................................................................... 50제 8 장 결 론 .............................................................................................................. 56참 고 문 헌 ........................................................................................................................... 57
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