مطالعه تجربی تاثیر نسبت انسداد انژکتور کم چرخش بر حدود پایداری و رژیم های احتراقی شعله گاز طبیعی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 کارشناس ارشد هوافضا-پیشرانش

2 استادیار گروه مهندسی هوافضا دانشکده فناوریهای نوین دانشگاه شهید بهشتی

چکیده

در این مطالعه، به بررسی تاثیر نسبت انسداد چرخاننده کم­ چرخش بر حدود پایداری و رژیم­ های احتراقی شعله پرداخته می ­شود. نسبت انسداد برابر سطح مسدود و پوشیده صفحه مغشوش­ کننده  به کل مساحت آن است و یکی از پارامترهای اصلی چرخاننده کم­ چرخش است که تاثیر مهمی بر پایداری شعله کم ­چرخش دارد. به­ منظور بررسی تاثیر نسبت انسداد کانال مرکزی چرخاننده بر پایداری، 9 چرخاننده با هندسه متمایز مورد بررسی قرار گرفتند. نتایج نشان داد که با افزایش نسبت انسداد، حد خاموشی چرخاننده­ ها کاهش می ­یابد، به طوری که با افزایش نسبت انسداد از 43% تا 76%، میزان حد خاموشی تا حدود 25% کاهش یافته و پایداری شعله بهبود می ­یابد. همچنین، در این مطالعه مشاهده شد که با افزایش نسبت هم ­ارزی، شعله یک فرایند گذار را طی می کند که در آن شعله از یک حالت Vشکل (کاسه­ ای شکل) معلق پایدار تا حالت گردابه­ ای­ شکل متصل به دهانه مشعل پیش می ­رود. فرایند گذار را می­توان به سه رژیم احتراقی متفاوت تقسیم کرد که حدود این رژیم­ های احتراقی براساس نسبت هم ­ارزی و میزان عدد رینولدز ورودی مشعل تعیین می­شود. بررسی میزان آلاینده  چرخاننده­ ها نشان داد که میزان  با افزایش نسبت هم ­ارزی افزایش می ­یابد و در نسبت­ های  هم ­ارزی نزدیک 1 میزان  در حدود ppm20 است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental study of the effects of low swirl injector blockage ratio on stability limits and combustion regimes of natural gas flame

نویسندگان [English]

  • Navid Heshmati 1
  • seyyed mehdi mirsajedi 2
1 New technologies department shahid beheshti university Tehran iran
2 New technologies department shahid beheshti university Tehran iran
چکیده [English]

In this study, the effect of a low swirl injector blockage ratio on the flame stability limits is investigated by using a low swirl burner. The blockage ratio is one of the main geometrical parameters of the low-swirl injector which has a significant impact on the stability of the flame. In order to investigate the influence of the blockage ratio of the central channel of low swirl injector on stability, nine swirler with distinct geometries were investigated. The results showed that with increasing the blockage ratio, the flame extinction limit was reduced so that increasing the blockage ratio from 43% to 76% reduced the extinction limit to about 25% and improved flame stability. It was also observed in this study that by increasing the equivalence ratio, the flame undergoes a transition process in which the flame proceeds from a stable lifted bowl shape to a vortex shape attached to the burner nozzle. The transition process can be divided into three different combustion regimes and in this study, these limits presented based on the equivalence ratio and the Reynolds number of the burner inlet. Evaluation of NOx pollutants of swirlers showed that Nox increased with increasing equivalence ratio and at equivalence ratios near stoichiometric values, the Nox level was about 20 ppm.

کلیدواژه‌ها [English]

  • Low swirl combustion
  • flame stability
  • blockage ratio
  • Natural gas
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