کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6593638 1423545 2018 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Formation and stabilization of multiple ball-like flames at Earth gravity
ترجمه فارسی عنوان
شکل گیری و تثبیت شعله های توپ چندگانه در گرانش زمین
کلمات کلیدی
تعداد کم لوئیس، محدود بودن اشتعال پذیری، شعله مانند توپ، هیدروژن متان،
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
چکیده انگلیسی
Near-limit low-Lewis-number premixed flame behavior is studied experimentally and numerically for flames of H2-CH4-air mixtures that are located in a 55 mm diameter tube and below a perforated plate in a downward mixture flow. A combustion regime diagram is experimentally identified in terms of equivalence ratio and ratio of H2 to CH4 (variation of fuel Lewis number). Planar flames, cell-like flames, distorted cap-like flames, and arrays of ball-like flames are progressively observed in the experiments as the equivalence ratio is decreased. The experimentally observed ball-like lean limit flames experience chaotic motion, which is accompanied by sporadic events of flame splitting and extinction, while the total number of simultaneously burning flamelets remains approximately the same. In separate experiments, the multiple ball-like lean limit flames are stabilized by creating a slightly non-uniform mixture flow field. The CH* chemiluminescence distributions of the lean limit flames are recorded, showing that the ball-like lean limit flame front becomes more uniform in intensity and its shape approaches a spherical one with the increase of H2 content in the fuel. Numerical simulations are performed for single representative flames of the array of stabilized flamelets observed in the experiments. The simulated ball-like lean limit flame is further contrasted with the single ball-like flame that forms in a narrow tube (13.5 mm inner diameter) with an iso-thermal wall. The numerical results show that the ball-like lean limit flames present in the array of ball-like flames are more affected by the buoyancy-induced recirculation zone, compared with that in the narrow tube, revealing why the shape of the ball-like flame in the array deviates more from a spherical one. All in all, the wall confinement is not crucial for the formation of ball-like flames at terrestrial gravity.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Combustion and Flame - Volume 192, June 2018, Pages 35-43
نویسندگان
, , , , ,