Analysis of turbulent burning velocity of spherically propagating premixed flame with effective turbulence intensity

Burning velocity of spherically propagating turbulent flames kept increasing with flame propagation. On the other hand, turbulent burning velocity obtained from burner stabilized flame is constant for a given turbulence intensity. This difference of turbulent burning velocity characteristic was discussed by Abdel-Gayed and Bradley et al. For spherically propagating flames, not all turbulent eddies contribute to the turbulence that affect the turbulent flame. Small flames may be wrinkled only by small scale turbulent eddies. As the flame propagates, it becomes progressively wrinkled by the larger eddies. The turbulence which contributes to turbulent flame may increase with the increase in flame radius. This increase in turbulence may cause the increase in turbulent burning velocity. The effective turbulence intensity was proposed by Abdel-Gayed and Bradley et al. as the turbulence intensity which contributes effectively to turbulent flame. In this study, the turbulence characteristics which are necessary for obtaining the effective turbulence intensity were evaluated by Particle Image Velocimetry (PIV) measurement. Then turbulent burning velocity of iso-octane/air flame was investigated with effective turbulence intensity. The turbulent burning velocity increased with the increase in effective turbulence intensity. The increase in turbulent burning velocity may be caused by the increase in flame front area with increase in the effective turbulence intensity.