DİFÜZÖR TİPİ YANMA ODASINDA GERÇEKLEŞEN ÖN KARIŞIMLI TÜRBÜLANSLI YANMADA ORTAYA ÇIKAN ALEVİN KONUMUNUN TÜRBÜLANS YOĞUNLUĞU VE TÜRBÜLANS UZUNLUK ÖLÇÜSÜ İLE DEĞİŞİMİNİN SAYISAL OLARAK İNCELENMESİ

Year 2018, Volume: 38 Issue: 1, 55 - 64, 30.04.2018

Ibrahim Nazzal Özgür Ertunç

Abstract

Bu makalenin amacı, ön karışımlı yanma sonucu oluşan alevin, çeşitli türbülans yoğunluklarına ve türbülans uzunluk ölçeğine maruz kalması sonucu oluşan alev yeri değişikliğini incelemektir. Yakıtın yanma odasına giriş hızını değiştirmeden, sadece türbülans yoğunluğunun ve türbülans uzunluk ölçeğinin alev yeri üstüne etkisini görebilmek için araştırmalar difüzör tipi yanma odasında gerçekleştirilmiştir. Propanın türbülanslı ön karışımlı yanma simulasyonları tutarlı alev modeli (coherent flame model) kullanılarak kararlı akış rejiminde gerçekleştirilmiştir. Orta ve yüksek türbülans uzunluk ölçeği kullanıldığında türbülans yoğunluğundaki artış ile alevin difüzörün girişine doğru hareket ettiği gözlemlenmiştir. Düşük uzunluk ölçeği kullanılarak gerçekleştirilen simulasyonlarda, alev türbülans yoğunluğunun artması ile girişe doğru yaklaştığı ancak türbülans yoğunluğunun daha da arttılmasına rağmen alev konumunda kayda değer bir değişiklik olmadığı gözlemlenmiştir. Sonuçlar, türbülans yoğunluğu ve türbülans uzunluk ölçeğindeki artışın, maksimum alev alan yoğunluğunu arttırdığını göstermektedir. Dahası türbülans yoğunluğunun ve uzunluk ölçeğinin alev alan yoğunluğu, alevin şekli ve konumu üzerinde aynı anda etkili olduğu gösterilmiştir.

Keywords

Türbülanslı ön karışımlı yanma, alev alan yoğunluğu, türbülans yoğunluğu, türbülans uzunluk ölçeği, tutarlı alev modeli

NUMERICAL INVESTIGATION OF THE FLAME LOCATION OF TURBULENT PREMIXED COMBUSTION IN A DIFFUSER BURNER EXPOSED TO VARIOUS TURBULENCE INTENSITIES AND TURBULENCE LENGTH SCALES

Abstract

This study aims to investigate the response of the flame location of a turbulent premixed flame that has been exposed to various turbulence intensities and turbulence length scales. A diffuser-type burner is used to reveal the influence of turbulence intensity and turbulence length scales on the flame location of premixed propane–air flames without changing the inlet velocity of the fuel. Numerical simulations are performed for the turbulent premixed propane flames by using a coherent flame model under steady-state conditions. Results show that the flame location moves toward the inlet of the diffuser combustor with an increase in turbulence intensity for moderate and high turbulence length scales. The behavior of the flame location is different for the low turbulence length scale. The flame location initially decreases with an increase in turbulence intensity and subsequently stabilizes. Furthermore, the maximum flame area density is shown to increase with an increase in the turbulence intensity and the turbulence length scale, as the flame moves toward the inlet in these cases. It is clearly documented how turbulence intensity and turbulence length scale simultaneously influence the flame area density, flame shape, and flame location in a diffuser- type burner.

Keywords

Premixed turbulent combustion, flame area density, turbulence intensity, turbulence length scale, coherent flame model

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