稳定环形分层火焰

Stereoscopic Planar Image Velocimetry (SPIV) has been applied to obtain the threecomponents of the instantaneous velocity vectors on a vertical plane above the burneroutlet where the flames propagate. The instantaneous temperature fields have beendetermined through Laser Induced Rayleigh (LIRay) scattering. Planar Laser InducedFluorescence (PLIF) on acetone has been used to calculate the average equivalence ratiodistributions. Instantaneous turbulent burning velocities have been extracted from SPIVresults, while flame curvature and flame thermal thickness values have been calculatedusing the instantaneous temperature fields. The probability distributions of thesequantities have been compared considering the separate influence of equivalence ratiostratification and turbulence. It has been observed that increased levels of turbulencedetermine higher turbulent burning velocities and flame front wrinkling. Flamescharacterized by stronger fuel stratification showed higher values in turbulent burningvelocities. From the curvature analysis emerged that increased fuel concentrationgradients favour flame wrinkling, especially when associated with positive small radiusof curvature. This determines an increased surface area available for reaction thatpromotes a faster propagation of the flame front in the oncoming combustible mixtures.

A burner for investigating lean stratified premixed flames propagating in intenseisotropic turbulence has been developed. Lean pre-mixtures of methane at differentequivalence ratios are divided between two concentric co-flows to obtain annularstratification. Turbulence generators are used to control the level of turbulence intensityin the oncoming flow. A third annular weakly swirling air flow provides the flamestabilization mechanism. A fundamental characteristic is that flame stabilization doesnot rely on flow recirculation. The flames are maintained at a position where the localmass flux balances the burning rate, the result is a freely propagating turbulent flamefront. The absence of physical surfaces in the vicinity of the flame provides free accessfor laser diagnostics.Stereoscopic Planar Image Velocimetry (SPIV) has been applied to obtain the threecomponents of the instantaneous velocity vectors on a vertical plane above the burneroutlet where the flames propagate. The instantaneous temperature fields have beendetermined through Laser Induced Rayleigh (LIRay) scattering. Planar Laser InducedFluorescence (PLIF) on acetone has been used to calculate the average equivalence ratiodistributions. Instantaneous turbulent burning velocities have been extracted from SPIVresults, while flame curvature and flame thermal thickness values have been calculatedusing the instantaneous temperature fields. The probability distributions of thesequantities have been compared considering the separate influence of equivalence ratiostratification and turbulence.

LaVision imager intense型CCD相机加上图像增强器IRO构成了一套OH自由基激光诱导荧光测量系统。利用这套系统对旋转稳定的贫预混合火焰燃烧动力学：火焰稳定化，火焰动力学和燃烧不稳定控制策略等进行了实验研究