非预混旋流火焰中部熄火及重新稳燃机理研究

• The effects of quarl on the non-premixed swirling flames were studied by performing simultaneous OH-PLIF/PIV measurements experimentally and coupling LES with PDF combustion model numerically. The results showed that LES-PDF method can successfully capture the swirl flow fields and flame structures even including local extinction and re-stabilization. Compared to the no quarl case, the quarl plays a significant role on the expansion of the recirculation zone thus influencing the attached flame and the following extinction, though it affects the re-stabilization height rarely. With the high scalar dissipation rate, local extinction occurs due to the strong heat loss caused by the central fuel jet. In addition, fuel and air are partially premixed accompanied with some partial oxidation reactions producing CH2O, which provides preferential conditions for the stabilization of the non-premixed swirling flame. Moreover, the reaction rate term of OH is at least 10 times larger than its diffusion term, indicating that the reaction front dominates the re-ignition process for the flame re-stabilization downstream. It is thus concluded that the partially premixed flame propagation plays a dominant role in controlling the re-stabilization of this flame.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Nyckelord

Flame stabilization

LES-PDF

Local extinction

Reaction front

Swirl flames

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)