بررسی عددی اثر سطوح مختلف ناهمگنی بر طول شعله آشفته در محفظه احتراق

نوع مقاله: مقاله پژوهشی

نویسندگان

1 مهندسی مکانیک - دانشکده مهندسی - دانشگاه کاشان

2 عضو هیات علمی دانشکده مهندسی مکانیک - دانشگاه کاشان

چکیده

احتراق مخلوط واکنش‌دهنده‌های ناهمگن نوعی از احتراق است که در آن اختلاط سوخت و هوا به­ طور کامل انجام نمی­ شود. از آنجا که مطالعات گذشته بر روی این نوع احتراق در فضای باز انجام‌ شده، هدف این تحقیق بررسی عددی مشاهده اثر سطوح مختلف ناهمگنی بر طول شعله در دبی‌ها و نسبت هم‌ارزی‌های مختلف در فضای بسته و بدون حضور هوای محیط و نفوذ آن بر شعله است. در این بررسی عددی از مدل‌سازی معادلات ناویراستوکس به روش میانگین‌گیری رینولدز و مدل‌سازی آشفتگی k-ε استاندارد و مدل‌سازی جریان واکنشی روش اتلاف گردابه‌ای EDC استفاده ‌شده است. همچنین، در این مطالعه از سینتیک GRI2.11 استفاده‌ شده است. مشاهدات نشان می‌دهد که میزان طول شعله در طول ناهمگنی مشخصی کمینه می‌شود، به‌طوری‌ که در طول‌های ناهمگنی قبل و بعد از آن، طول شعله افزایش می‌یابد. این طول ناهمگنی با تغییر دبی و تغییر نسبت هم‌ارزی‌ متفاوت است. همچنین، نتایج نشان می‌دهد که طول شعله در حالت غیرپیش ­مخلوط کمتر از طول شعله در حالتی است که مخلوط سوخت و هوا به‌صورت پیش­ مخلوط در محفظه مشتعل می‌شوند. ولی، هرچه نسبت هم‌ارزی کاهش پیدا می‌کند، اختلاف کمتر می‌شود، به‌طوری‌ که در نسبت هم‌ارزی‌های کمتر طول شعله در حالت غیرپیش­ مخلوط بیشتر از حالت پیش­ مخلوط می‌شود. همچنین، سطح مقطع شعله در داخل محفظه چه در جهت طولی و چه در جهت عرضی با تغییر طول ناهمگنی تغییر می‌کند.
 

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical study of The effect of different levels of inhomogeneity on turbulent flame length in combustion chamber

نویسنده [English]

  • seyed mohammad mahdi sabet 1
1 PhD student of Kashan University
چکیده [English]

Combustion of a mixture of inhomogeneity reactants is a type of combustion that has been used since 1997. All previous studies have been done on this type of outdoor combustion. The aim of this study was to investigate the numerical effect of different levels of inhomogeneity on flame length at different velocities and ratios in closed space without the presence of ambient air and its influence on flame. In this numerical study, the configuration modeling of Navier Stokes equations using Reynolds averaging method has been used. The results show that the flame length during a given inhomogeneity has a low limit so that the flame length increases before and after the inhomogeneity. This length of inhomogeneity varies at different velocities and equivalence ratios. The results also show that the flame length in the non-premixed state is less than the flame length when the fuel / air mixture is almost pre-mixed in the ignition chamber but as the equivalence ratio decreases, the difference is expected to be equal. The lower flame length values in the non-mixed state will be greater than the near-mixed state. Also, the cross-sectional area of the flame inside the chamber changes significantly both in length and width by changing the length of the inhomogeneity.

کلیدواژه‌ها [English]

  • Turbulent Combustion
  • Inhomogeneity
  • flame length
  • Combustion chamber
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