이중선회 인젝터 내 수소 함량에 따른 화염의 형상과 스트레치에 의한 재부착 거동 특성 = Flame Shape and Reattachment Behavior Induced by Stretch in a Dual-Swirl Injector with Hydrogen Content

다국어 초록 (Multilingual Abstract)

In this study, the flame shape and reattachment behavior of CH₄/H₂ co-firing flames in a dual-swirl injector were experimentally investigated. The injector consists of a main passage supplying premixed methane/air and a pilot passage injecting hydrogen. High-speed OH planar laser-induced fluorescence (OH-PLIF) was employed to analyze the flame structure and spatial distribution under various hydrogen contents and global equivalence ratios. The flame exhibited two shapes, namely lifted and attached flames, depending on the anchoring behavior at the pilot nozzle. Quantitative flame shape parameters, including flame width and pilot flame lift-off height, were extracted using an OTSU-based image processing technique. The results showed that both parameters increased with hydrogen content and global equivalence ratio, while decreasing with increasing main equivalence ratio. To elucidate the underlying mechanism, one-dimensional counterflow flame simulations using the OPPDIF code were performed to evaluate local flame stretch characteristics. The numerical results showed trends consistent with the experimental observations, indicating that flame reattachment was closely associated with variations in local strain rate. In addition, particle image velocimetry (PIV) measurements revealed strong recirculation and shear layers near the pilot nozzle in lifted flame conditions, which enhanced flame stretch and promoted local extinction. These results demonstrate that the lift-off and reattachment behavior of dual-swirl CH₄/H₂ flames can be effectively interpreted in terms of flame stretch and flow–flame interaction.

목차 (Table of Contents)

• Ⅰ. 서론 1
• 1. 연구 배경 1
• 2. 연구 동향 5
• 3. 연구 목적 9
• Ⅱ. 실험 장치 및 방법 10
• 1. 실험 장치 10
• 2. 실험 및 수치해석 방법 18
• Ⅲ. 결과 및 고찰 23
• 1. 이중선회 화염의 구조 및 형상 23
• 2. 1차원 수치해석을 통한 이중선회 화염 모사 49
• 3. 화염 스트레치에 의한 재부착 거동 55
• Ⅴ. 결론 62