Abstract: The results of experimental study on reacting flow behind a swirler by LDA are presented in this paper. The experiments show that there exists a twin recircu-lation zone behind the cup shaped swirler with a hole in the middle of its plain bottom, and sudden changes in turbulent fluctuation velocity occur in the boundary region of the recirculation zones, and also there appear two peaks in the profile of probability density function of the fluctuation velocity in that zones. The temperature profiles obtained by thermocouple show that there exist two branches of flame,outer and inner flames, starting and spreading downstream from the outside and inside boundaries of the twin recircu-lation zone. The experiment results may be used as a basis to improve the performance of a combustor with swirler, and also to develop the numerical method for turbulent reacting flow with recirculation.

Key words: turbulent reacting flow field, swirl flow, LDA measurement