지원사업
학술연구/단체지원/교육 등 연구자 활동을 지속하도록 DBpia가 지원하고 있어요.
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연구자들이 자신의 연구와 전문성을 널리 알리고, 새로운 협력의 기회를 만들 수 있는 네트워킹 공간이에요.
논문 기본 정보
- 자료유형
- 학위논문
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- 지도교수
- 백두성
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- 2014
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지금 세계적으로 환경문제는 크게 대두되고 있다. 지구온난화는 물론 세계적으로 기후 변화가 일어나고 있다. 그래서 환경적인 문제가 선택사항이 아닌 필수가 되고 있는 상황이다. 북미와 유럽뿐만 아니라 국내에서도 지속적으로 강화되고 있는 배기가스 배출물(HC, CO, NOx) 규제와 더불어 지구온난화의 주원인으로 파악되는 CO2 배출량도 국제적으로 엄격히 규제되고 있다. 자동차 업계에서는 과거보다 좋은 연비와 효율을 늘리기 위해 많은 노력을 하고 있다. 그 중 하나가 GDI 엔진이다. 과거에 많이 사용하던 MPI(Multi Point Injection)엔진은 포트에 연료를 분사하는 방식으로써 혼합기를 실린더에서 연소시킨다. 이와 다르게 GDI 엔진은 Injector를 흡기포트 부근 실린더 상단에 비스듬히 설치하여 Injector hole이 실린더 안으로 직접 향하도록 하며 공기 흡입과는 별개로 흡입행정 또는 압축행정 중에 연료 분사가 이루어진다. 또한 보통엔진은 특정한 회전영역에서 최대출력을 얻을 수 있도록 밸브 개폐 시기 및 개폐량이 정해져있다. 저속에서는 밸브 오버랩이 길면 체적효율이 저하된다. 반대로 고속에서는 흡기밸브의 개방지속기간이 길어야 출력이 증가한다. 즉 고속에서는 밸브 오버랩이 길어야한다. 이 연구는 이러한 장점을 가진 GDI엔진에 가변 밸브 타이밍을 적용하였을 때의 유동을 수치 해석하였다. 유동 해석을 함으로써 효율의 증가시킬 수 있는 기초 자료가 되었으면 한다.
목차
목 차Ⅰ. 서론 ·········································································· 11.1 연구의 배경 ································································· 11.2 연구의 목적 ································································· 3Ⅱ. 이론적 배경 ································································· 52. GDI 엔진 ···································································· 52.1 GDI 엔진의 개요 ··························································· 52.2 GDI 엔진의 특징 및 장단점 ·············································· 7Ⅲ. 이론 해석 ···································································· 83.1 체적효율 ····································································· 83.2 난류 모델 모델 ······················································· 8Ⅳ. 수치해석 기법 및 방법 ··················································· 114.1 수치 해석 기법 ···························································· 134.1.1 유한요소 프로그램의 개요 및 구성 ··································· 134.2 수치 해석 방법····························································· 154.2.1 해석모델의 구성 ························································· 15Ⅴ. 결과 및 고찰 ······························································ 195.1 Crank angle 0°, 2500rpm ················································ 195.2 Crank angle 10°, 2500rpm ··············································· 245.3 Crank angle 0°, 3000rpm ················································ 285.4 Crank angle 10°, 3000rpm ··············································· 335.5 Crank angle 0°, 5000rpm ················································ 385.6 Crank angle 10°, 5000rpm ··············································· 42Ⅵ. 결론 ········································································· 48Reference ······································································· 49
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