## In the laminar regime since Wf kept

Additionally, Fig. 4b also demonstrates that at a given uco, both the laminar and turbulent Wf∗ kept constant, irrelevant with df and Ref. To investigate the effect of uco on Wf∗ quantitatively, the averages of the measured laminar and turbulent Wf∗ at constant df (df = 1.98 mm) but various uco (uco = 1, 3, 5, and 7 m/s) were calculated and are displayed in Fig. 5, respectively. It indicates that Wf∗ of the turbulent flame was about twice that of the laminar one. In Ref. [10], it Tariquidar was attributed to variation of the fuel Schmidt number (Scf) in the transitional regime. Fig. 5 also shows that Wf∗ decreased with uco exponentially, regardless of the fluid regime. When uco was above 5 m/s, the curves became flat, indicating that the effect of uco on Wf∗ became insignificant gradually. Given the fact that the exponents −0.325 and -0.32 for the laminar (Wf∗ = 1.2 uco-0.325) and turbulent (Wf∗ = 2.4 uco-0.32) fitting curves are approximately equal, transition reaction was assumed that Wf∗ was proportional to uco-0.32, regardless of the fluid regime, i.e.:equation(17)Wf∗∼uco-0.32