STATISTICAL OH-ZONE STRUCTURES OF TURBULENT JET FLAMES FROM LIFTOFF TO NEAR-BLOWOUT

Joint Reactive-Me-Scattering (RMS) and Planar-Laser-Induced-Fluorescence (PLIF) techniques have been employed to study the impact of jet-shear-layer development upon flame behavior. Images of the complete penetration of the shear-layer vortex through the flame surface.have been successfully captured utilizing these planar imaging techniques. Studies of these images have indicated that the degree of flame/flow interaction varies with respect to a wide range of flame conditions and results in the observation of several different types of flame zones—flamelels, multiple flamelets, thick flame zones, and local extinction. The probability of observing the different types of flame behavior was measured, and the results are presented Analysis of the probability data indicates that the root-mean-square (rms) flame-surface fluctuation, L. provides a proper length for correlating the statistical behavior of the flame. Significant changes in the flame behavior were observed to occur at two critical values of L—the minimal thermal thickness (— I mm) and the nozzle diameter (5 mm). © 1991 Gordon and Breach Science Publishers S.A.