• Title/Summary/Keyword: Negative part of fluctuating velocity

Search Result 1, Processing Time 0.015 seconds

A Combustion Characteristics of Attached Jet Flame under the Regular Oscillation (규칙적인 진동 하에서 노즐 부착된 제트화염의 연소특성)

  • Kim, Dae-Won;Lee, Kee-Man
    • Fire Science and Engineering
    • /
    • v.23 no.1
    • /
    • pp.55-62
    • /
    • 2009
  • A general combustion characteristics of forcing nonpremixed jet in laminar flow rates have been conducted experimentally to investigate the effect of forcing amplitude with the resonant frequency of fuel tube. There are two patterns of the flame lift-off feature according to the velocity increasing; one has the decreasing values of forcing amplitude on the lift-off occurrence when a fuel exit velocity is increasing, while the other has the increasing values. These mean that there are the different mechanisms in the lift-off stability of forced jet diffusion flame. Especially, the characteristics of attached jet flame regime are concentrically observed with flame lengths, shapes, flow response and velocity profiles at the nozzle exit as the central figure. The notable observations are that the flame enlogation, in-homing flame and the occurrence of a vortical motion turnabout have happened according to the increase of forcing amplitude. It is understood by the velocity measurements and visualization methods that these phenomena have been relevance to an entrainment of surrounding oxygen into the fuel nozzle as the negative part of the fluctuating velocity has begun at the inner part of the fuel nozzle.