نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده مهندسی هوافضای دانشگاه صنعتی شریف، تهران، ایران
2 دانشکده مهندسی هوافضا دانشگاه صنعتی شریف، تهران، ایران
3 دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف، تهران، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In spark ignition engines, local or global flame extinction may occur after the ignition spark deactivates, posing challenges to engine stability. Identifying and predicting this phenomenon is crucial for addressing combustion instability. This study investigates the acoustic extinction of a partially premixed methane-air counterflow flame. The focus is on the impact of fuel-air mixing on flame behavior under acoustic waves, using non-intrusive CH* chemiluminescence. One-dimensional steady flame simulations, alongside flame chemiluminescence and spectrometry, are employed to discern differences in flame structure among various mixing regimes. The stagnation point of the reactant jet varies with the momentum flux ratio of upper and lower nozzle flows; while mixing effects alter temperature and CH* radical distributions. Experimental results reveal that at low frequencies (~20 Hz), the non-premixed flame, due to its mixing time scale, exhibits lower stability and extinguishes at lower acoustic pressure levels compared to the other flames. Mixing effects on extinction are notable up to 55 Hz, beyond which they become negligible. CH* chemiluminescence analysis of the partially premixed flame shows reduced thickness, area, and average heat release rate at low frequencies compared to the steady-state flame. With increasing frequency, these parameters increase compared to the steady-state flame; however, higher-frequency acoustic waves have minimal impact on flame structure.
کلیدواژه‌ها [English]
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