A burner for investigating lean stratified premixed flames propagating in intense
isotropic turbulence has been developed. Lean pre-mixtures of methane at different
equivalence ratios are divided between two concentric co-flows to obtain annular
stratification. Turbulence generators are used to control the level of turbulence intensity
in the oncoming flow. A third annular weakly swir领 air flow provides the flame
stabilization mechanism. A fundamental characteristic is that flame stabilization does
not rely on flow recirculation. The flames are maintained at a position where the local
mass flux balances the burning rate, the result is a freely propagating turbulent flame
front. The absence of physical surfaces in the vicinity of the flame provides free access
for laser diagnostics.
Stereoscopic Planar Image Velocimetry (SPIV) has been applied to obtain the three
components of the instantaneous velocity vectors on a vertical plane above the burner
outlet where the flames propagate. The instantaneous temperature fields have been
determined through Laser Induced Rayleigh (LIRay) scattering. Planar Laser Induced
Fluorescence (PLIF) on acetone has been used to calculate the average equivalence ratio
distributions. Instantaneous turbulent burning velocities have been extracted from SPIV
results, while flame curvature and flame thermal thickness values have been calculated
using the instantaneous temperature fields. The probability distributions of these
quantities have been compared considering the separate influence of equivalence ratio
stratification and turbulence. 德国LaVision PIV/PLIF粒子成像测速场仪 PLIF平面激光诱导荧光火焰燃烧检测系统 时间分辨平面激光诱导荧光测量系统
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