掺氢预混燃烧室火焰结构及动态压力特性研究

An experimental study was conducted on a premixed combustor using hydrogen-blended natural gas to gain a deeper understanding of the effects of hydrogen blending ratio (HBR) on swirling flame characteristics and dynamic pressure. High-speed imaging and flame chemiluminescence techniques were used to capture the instantaneous spatial distribution of key combustion species under different HBR, and steady-state flame distribution characteristics were obtained through image overlay. Proper orthogonal decomposition (POD) was applied to identify the dominant modes of key species distribution and their spectral characteristics. Additionally, dynamic pressure measurements were conducted at different locations within the combustor, and their spectral characteristics were analyzed. The results show that, compared to pure natural gas conditions, the steady-state flame structure undergoes significant changes with hydrogen-blended fuel. As the HBR increases, the relative position of the high-concentration regions of CH* and OH* shifts:at HBR=10%, CH* is located outside OH*, whereas at HBR=40%, CH* appears inside OH*. With increasing HBR, the spatial distribution characteristics of the POD modes of CH* and OH* change significantly at HBR=30%, disrupting the previously stable swirling flame structure and introducing low-frequency circumferential oscillations. When the HBR reaches 40%, the first-order POD mode of CH* and OH* transitions to an axial distribution pattern. The dominant frequency of dynamic pressure measurements at different locations remains consistent. As the HBR increases from 0% to 30%, the dominant frequency of dynamic pressure slightly rises while staying within the range of 70~76 Hz. However, at HBR=40%, the dominant frequency significantly increases to 196.95 Hz, which aligns with the variation in the highest dominant frequency of the first- and second-order POD modes of OH*, where their energy exceeds 80% as the HBR changes.