بررسی تاثیر الگوی پاشش اسپری سوخت بر تبخیر قطرات در لوله پیش مخلوط توربین گاز

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری، مهندسی مکانیک، دانشگاه تربیت مدرس، تهران، ایران

2 دانشیار گروه تبدیل انرژی دانشکده مهندسی مکانیک/دانشگاه تربیت مدرس

3 دانشکده هوا و فضای، دانشگاه خواجه نصیرالدین طوسی

چکیده

در سیستم احتراق یک توربین گاز سوخت مایع، به دلیل محدودیت طول لوله پیش مخلوط، فرآیند تبخیر قطرات سوخت به طور کامل انجام نمی‌گیرد و قطرات وارد محفظه احتراق می‌شوند. وجود این قطرات در محفظه احتراق باعث می‌گردد که اشتعال در حالت غیر پیش مخلوط انجام شود و متعاقب آن میزان نشر اکسیدهای نیتروژن افزایش یابد. برای جلوگیری از نشر این آلاینده‌ها، می‌بایست قطرات اسپری در یک فضای محدود به طور کامل تبخیر گردد. بدین منظور در این جا، یک مکانیزم برای پاشش قطرات سوخت در لوله پیش مخلوط ارائه شده است. در این مکانیزم، قطرات اسپری با الگوی مخروط توخالی در خلاف جهت جریان هوا تزریق می‌شود. بنابراین در این نوع پاشش، به دلیل افزایش سرعت نسبی قطرات و تسریع در فرآیندهای شکست و تبخیر آنها، دستیابی به این هدف امکان‌پذیر می‌باشد. در بررسی صحت این موضوع، الگوهای مختلفی از پاشش قطرات ان-هپتان در گاز ازت عبوری از لوله پیش مخلوط با دمای 800 کلوین و فشار 20 بار در سیستم اویلری - لاگرانژی شبیه‌سازی شده است. اعتبار مدل‌های توربولانس، انتقال جرم و حرارت و نیز اثر نفوذ مولکول‌های گاز به داخل قطرات سوخت در فشار بالای محیط ارزیابی شده است. نتایج حاصل نشان می‌دهد که با تزریق قطرات اسپری با الگوی اشاره شده، علاوه بر تبخیر کامل قطرات در فضای محدود، توزیع دما و کسر جرمی بخار سوخت در خروجی لوله نیز یکنواخت می‌گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of the Effect of Spray Fuel Injection Pattern on Evaporation of Droplets in the Gas Turbine Pre-mixer

نویسندگان [English]

  • Ahmad Kazemi Fard 1
  • Hassan Khaleghi 2
  • Reza Ebrahimi 3
1 Mechanical Engineering Department, Tarbiat Modares University, Tehran, Iran
2
3 Aerospace Engineering Department, K.N. Toosi University of Technology, Tehran, Iran.
چکیده [English]

In a liquefied gas turbine combustor, due to the limited length of the premix tube, the evaporation process of fuel droplets is not completely carried out inside the tube, and the droplets enter the combustion chamber. The presence of droplets in the combustor causes the reactions to occur in the non-premix mode and the emission of NOx increases as a result. To avoid the emission of this pollutant, it is necessary that the droplets are evaporated completely in a limited space. Herein, a mechanism is proposed for spraying the droplets, in which, fuel droplets are injected to form a hollow-cone spray pattern in the opposite of the gas flow direction. In this type of injection, due to the relative velocity of droplets and subsequent enhancement of the droplet break-up and evaporation processes, it is possible to achieve this goal. To verify this matter, various patterns of injected n-heptane droplets into nitrogen gas passing through a premix tube have been simulated at the temperature of 800 K and the pressure  of 20 bar using the Eulerian-Lagrangian approach. The validation of heat and mass transfer models, as well as the influence of gas molecules penetration into fuel droplets, has been evaluated. The results showed that using this type of injection, in addition to full evaporation of droplets in the limited space, the distribution of the temperature and the fuel vapor mass fraction in the tube outlet are more evenly distributed

کلیدواژه‌ها [English]

  • Premix tube
  • Droplet evaporation
  • High pressure
  • Fuel injection
  • Gas turbine
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