Investigation of the Elementary Process in Turbulent Combustion

紊流扩散火焰应该是层流小火焰的集合，这些小火焰应该是不稳定应变的，具有正曲率或负曲率，并受到优先扩散的影响。本研究采用二维时变激光瑞利散射法和OH激光诱导荧光法对实验火焰进行了可视化，并对温度和OH浓度进行了定量检测。数值研究还考虑了详细的化学动力学和多组分扩散，以预测实验证据的特征，并揭示了火焰曲率和火焰拉伸方面控制火焰瞬态行为的过程。研究了火焰拉伸、火焰曲率、优先扩散、拉伸的非定常性和局部性对火焰温度和火焰熄灭的影响。(1)采用瑞利散射二维温度检测技术，研究了正应变和负应变、火焰曲率和非定常对火焰温度和局部消光的影响。(2)利用声激励燃料流形成与大尺度涡相互作用的火焰，通过激光诱导荧光检测OH浓度和瑞利散射检测温度来研究火焰与涡的相互作用，注意相互作用引起的局部消光。(3)对上述火焰进行了数值模拟，考虑了多组分扩散和详细的化学动力学，明确了火焰与流体力学的相互作用。由于非定常性和局域性的原因，大拉伸时应引起局部淬火，但不一定引起火焰淬火。指出火焰熄灭是由于燃料或氧化剂的缺陷与涡流相互作用引起的。少

The turbulent diffusion flame is supposed to be an ensemble of the laminar flamelets which should be strained unsteadily and have positive or negative curvature, and be affected by preferential diffusion. In this study, experimental flame visualization and quantitative detection of temperature and OH concentration were conducted by use of the two-dimensional time-dependent laser Rayleigh scattering and OH laser induced fluorescence methods. Numerical studies were also conducted taking into account detailed chemical kinetics and multi component diffusion to predicted the characteristics of the experimental evidence and revealed the processes dominating the transient behavior of the flame with respect to the flame curvature and flame stretch. Attentions were paid to the effects of the flame stretch, flame curvature, preferential diffusion, unsteadiness and locality of the stretch on the flame temperature and flame extinction.(1) Flames with a controlled steady and unsteady strain were fo … More rmed to investigate the effects of positive and negative strain, flame curvature and unsteadiness on the flame temperature and local extinction by use of the two dimensional temperature detection by Rayleigh scattering.(2) Flames interacted with large scale vortices were formed by acoustic excitation to the fuel flow to investigated the interaction between flame and vortex by the detection of the OH concentration by the laser induced fluorescence together with and temperature detection by Rayleigh scattering paying attention to the local extinction due to the interaction.(3) Numerical simulation was conducted of the flames noted above taking into account multi component diffusion and the detailed chemical dynamics to make clear the interaction of the flame and the fluid dynamics. The large stretch which should induce the local quenching does not necessarily induce the flame quenching due to the unsteadiness and locality. It is also pointed out that the flame extinction is induced by the defect of the fuel or oxidizer interacted with the vortex. Less