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Proceedings of Symposium on Energy Engineering in the 21<sup>st</sup> Century (SEE2000) Volume I-IV

ISSN:
1-56700-132-7 (Print)

THE GEOMETRIC APPEARANCE OF THE COUNTERFLOWING PREMIXED FLAME UNDER HIGH TURBULENT INTENSITY

Yiqian Xu
Thermoenergy Engineering Research Institute Southeast University, Nanjing, China

Hongmin Yang
Thermoenergy Engineering Research Institute Southeast University, Nanjing, China

Yong Liu
Thermoenergy Engineering Research Institute Southeast University, Nanjing, China

Weimin Ma
Thermoenergy Engineering Research Institute Southeast University, Nanjing, China

Fan Gu
Thermoenergy Engineering Research Institute Southeast University, Nanjing, China

Abstract

The counterflowing flame is a novel combustion manner with plenty of advantages for the researches on local characteristics of combustion under intensive turbulence. Using the laser tomography technology and the digital imaging processing technique, the experimental studies on the fine geometric characteristics of turbulent counterflowing premixed flame were carried out under various experimental conditions, such as Reynolds number, bulk strain, equivalence ratio and the ratio of counterflowing momentum. The velocity aspects near the counterflowing interface were measured by PIV technology in cold condition and the strain rates of tangent velocity were acquired to describe the influence of gradient of velocity on combustion. The special appearance of twin flame was discovered which resulted from the interaction between the vortex and the flame. Using the extracted fronts of flame, some discontinuous cusps and holes on the wrinkled boundaries were found in our experiments and this was thought to predict the extinction in local region under high turbulent intensity. Furthermore, Applying the fractal theory, the nonlinear fractal characteristics of the counterflowing flame fronts were investigated and it seems that there may be some relations between the fractal dimension and the turbulent intensity.