非表示:
キーワード:
PARTICLE IMAGE VELOCIMETRY; LASER-INDUCED FLUORESCENCE; JET DIFFUSION
FLAME; STRAIN-RATE; REPETITION-RATE; METHANE-AIR; SURFACE-DENSITY;
BUNSEN FLAMES; CURVATURE; COMBUSTIONOptics; Physics;
要旨:
This paper describes the simultaneous application of time-sequenced laser-induced fluorescence imaging of OH radicals and stereoscopic particle image velocimetry for measurements of the flame front dynamics in lean and premixed LP turbulent flames. The studied flames could be acoustically driven, to simulate phenomena important in LP combustion technologies. In combination with novel image post processing techniques we show how the data obtained can be used to track the flame front contour in a plane defined by the illuminating laser sheets. We consider effects of chemistry and convective fluid motion on the dynamics of the observed displacements and analyse the influence of turbulence and acoustic forcing on the observed contour velocity, a quantity we term as s (d) (2D) . We show that this quantity is a valuable and sensitive indicator of flame turbulence interactions, as (a) it is measurable with existing experimental methodologies, and (b) because computational data, e.g. from large eddy simulations, can be post processed in an identical fashion. s (d) (2D) is related (to a two-dimensional projection) of the three-dimensional flame displacement speed s (d) , but artifacts due to out of plane convective motion of the flame surface and the uncertainty in the angle of the flame surface normal have to be carefully considered. Monte Carlo simulations were performed to estimate such effects for several distributions of flame front angle distributions, and it is shown conclusively that s (d) (2D) is a sensitive indicator of a quantity related to s (d) in the flames we study. s (d) (2D) was shown to increase linearly both with turbulent intensity and with the amplitude of acousting forcing for the range of conditions studied.
