بررسی تاثیر زاویه همگرایی-واگرایی بر مشخصه‌های احتراقی مخلوط پیش‌آمیخته هیدروژن - هوا در یک میکرولوله همگرا – واگرا

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجو، رشته مهندسی مکانیک، دانشگاه شهید چمران اهواز، اهواز

2 استادیار، گروه حرارت و سیالات، دانشکده مهندسی مکانیک، دانشگاه شیراز، شیراز

3 دانشگاه شهید چمران اهواز، دانشکده مهندسی، گروه مهندسی نفت، گاز و پتروشیمی

چکیده

در مطالعه حاضر، مشخصه‌های احتراقی مخلوط پیش‌آمیخته هیدروژن-هوا در میکرولوله‌های همگرا-واگرا، با استفاده از شبیه‌سازی عددی فرایند احتراق، بررسی شده است. هدف این پژوهش بررسی تاثیر سرعت جریان ورودی و زاویه همگرایی-واگرایی بر مشخصه‌های احتراقی شامل بیشینه دمای شعله، موقعیت شعله، حدشعله‌وری بالا و ضخامت شعله در قطر در محدوده قطر خاموشی شعله است. معادلات حاکم به‌صورت سه‌بعدی و گذرا درنظر گرفته شده‌اند و از مکانیزم شیمیایی جزئی واکنش هیدروژن و هوا استفاده شد. نتایج نشان دادند که سرعت جریان ورودی بر موقعیت شعله درون میکرولوله تاثیر می‌گذارد و بیشینه دمای شعله متاثر از موقعیت قرارگیری شعله درون میکرولوله تغییر می‌کند. کمترین دمای شعله در یک نسبت هم‌ارزی مشخص زمانی ایجاد می‌شود که شعله در قسمت گلوگاه قرار گرفته باشد. مشخص شد که سرعت جریان ورودی و قسمت گلوگاه تاثیر مستقیمی بر ضخامت و کشیدگی شعله دارند. افزایش ضخامت و کشیدگی شعله در سرعت‌های زیاد، برای میکرولوله‌های با قطر گلوگاه کم، موجب بیرون زدن قسمتی از ناحیه احتراق از میکرولوله و درنهایت خارج­ شدن از حد شعله‌وری بالا می‌شود. از مقایسه نتایج با یک میکرولوله با مقطع ثابت و ابعاد مشابه مشخص شد که ایجاد ناحیه گلوگاه در میکرولوله‌ها موجب افزایش حد شعله‌وری بالا در آن‌ها می‌شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical study of premixed hydrogen/air combustion characteristics in a converging - diverging micro tube

نویسندگان [English]

  • Pouyan Abbaspour 1
  • Alireza Alipoor 2
  • Yousef Tamsilian 3
1 Student, Department of Mechanical Engineering, Shahid Chamran University of Ahvaz, Ahvaz
2 Shiraz University
3 Department of Oil, Gas & Petrochemical Eng., Faculty of Engineering, Shahid Chamran University of Ahvaz
چکیده [English]


 
In the present study, combustion characteristics of premixed hydrogen-air mixture in converging - diverging microtubes were investigated using numerical simulation of combustion process. The purpose is investigation of the effect of inlet velocity and converging-diverging angle on the combustion characteristics consist of maximum flame temperature, flame position, upper flammability limit and flame thickness. Governing equations were considered as three dimensional and transient with detailed chemistry mechanisms. Results showed that inlet velocity affect flame position in the microtube and maximum flame temperature related on the flame position will change. Minimum flame temperature in a specific equivalence ratio were occurred when the flame placed in the converging-diverging section. Inlet velocity and throat section have a direct effect on the flame thickness. Increasing the flame thickness at high inlet velocities for microtubes with low throat diameter causes to blow out a part of the flame. Compared to a microtube with the same dimensions, it was found that making a throat zone in the microtubes causes to increase the upper flammability limit.

کلیدواژه‌ها [English]

  • Converging Diverging Micro tube
  • Upper Flammability Limit
  • Flame Thickness
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