선형 안정성 이론 기반 극초음속 경계층 천이 지연을 위한 다공 표면 설계 = Design of Porous Surface for Hypersonic Boundary Layer Transition Delay Based on Linear Stability Theory

국문 초록 (Abstract)

비행체 표면에서의 마찰항력과 열전달은 경계층의 상태와 매우 밀접하게 연관되기
때문에 극초음속 비행체의 열공력성능, 임무성능을 향상시키기 위한 경계층 천이 제어
연구가 큰 관심을 받고 있다. 본 연구에서는 다공 표면이 극초음속 경계층 안정화와
천이에 미치는 영향을 분석하기 위해 선형 안정성 이론 기반의 안정성 해석기법을 구
축하였다. 구축한 해석기법으로 날카로운 원뿔 위 극초음속 경계층에 대한 Mack 2차
모드의 증폭률을 계산하고 선행연구 결과와의 비교를 통해 검증을 수행하였다. 검증해
석 결과 다공 표면 적용에 따라 최대 증폭률이 감소하였으며, 불안정한 영역이 상류로
이동함을 확인하였다. 기공 반경, 간격, 깊이, 단면 형상과 같이 다공 형상 파라미터에
따른 효과를 분석하였으며, 기공 내의 희박효과와 표면에서의 열적 어드미턴스가 해석
결과에 미치는 영향을 평가하였다. 또한, 반경험적 천이 예측 기법을 기반으로 다공 표
면의 천이 지연 효과를 분석하였다. 이를 바탕으로 최적 제어 효과를 가지는 다공 표
면 설계 방법을 탐색/제시하였다.

목차 (Table of Contents)

• 목차 ····································································································································· ⅰ
• List of Figures ··············································································································· ⅲ
• List of Tables ················································································································· ⅴ
• 요약 ···································································································································· ⅵ
• I. 서론 ··············································································································································· 1
• 1. 연구 배경 ············································································································································ 1
• 가. 연구의 필요성 ······························································································································· 1
• 나. 선행연구 ········································································································································ 2
• 2. 연구 목표 및 내용 ··························································································································· 3
• 가. 연구 목표 ······································································································································ 3
• 나. 연구 내용 ······································································································································ 3
• II. 유동 안정성 이론과 천이 예측 기법 ················································································ 4
• 1. 선형 안정성 이론 ·············································································································· 4
• 2. 지배방정식 ·························································································································· 5
• 가. 선형 교란 방정식 ····················································································································· 5
• 나. 선형 안정성 방정식 ················································································································· 6
• 3. 경계조건 ······························································································································ 7
• 가. 매끄러운 표면 ··························································································································· 7
• 나. 다공 표면 효과 모사 기법 ····································································································· 8
• 4. 수치적 기법 ······················································································································ 11
• 가. 계산 격자 변환 ······················································································································ 11
• 나. 행렬 고유치 문제 ·················································································································· 11
• 5. 선형 안정성 해석 방법 ·································································································· 11
• 6. 반경험적 천이 지점 예측 기법 ····················································································· 12
• III. 결과 및 해석 ··············································································································· 13
• 1. 해석기법 검증 ·················································································································· 13
• 가. 평균유동 ·································································································································· 13
• 나. 선형 안정성 해석기법 검증 ································································································· 16
• 1) 매끄러운 표면 ·················································································································· 16
• 2) 다공 표면 ·························································································································· 17
• 가) 다공 표면 적용 효과 ······························································································· 18
• 나) 열적 어드미턴스 영향 ····························································································· 19
• 다) 각 위치에서의 최대 증폭률 비교: 희박 효과 영향 ··········································· 20
• 2. 다공 표면 형상 파라미터 영향 분석 ··········································································· 21
• 가. 반경 영향 ································································································································ 21
• 나. 다공성 영향 ···························································································································· 22
• 다. 깊이 영향 ································································································································ 24
• 라. 기공 단면 형상 영향 ············································································································· 25
• 3. 다공 표면 설계 ················································································································ 27
• 가. 안정화 목표 교란의 주파수 설정 ······················································································· 29
• 나. 다공 표면 형상 파라미터의 유효 범위 확인 ···································································· 30
• 다. 형상 파라미터 조합에 따른 증폭률 비교 ········································································· 32
• 라. 천이 지점 예측 ······················································································································ 33
• IV. 요약 및 결론 ························································································································· 35
• V. Appendix ································································································································ 37
• 참고문헌 ········································································································································ 39
• Abstract ······································································································································· 43