Turbulence effects on accelerating turbulent premixed combustion

A detailed research on correlation analyses of turbulent characteristic parameters against turbulent combustion is made for methane/air charges in a combustion bomb, under the moderate turbulence conditions (u'/S_L = 0.5-4.5). The effects of turbulence intensity, flame size, and turbulent scale on turbulent combustion have been experimentally investigated. Experimental results report that there exists a linear coefficient, C, to describe the enhancing effectiveness of turbulence on turbulent burning velocity, i.e. turbulent burning velocity can be expressed as S_T/S_L = Cu'/S_L + 1, where C is a function of flame size and turbulent length scale. It is also shown that the linear coefficient, C, increases with the increase of flame size, which indicates that the premixed flames considered are not fully developed ones. The coefficient also decreases with increasing turbulent length scale. Through summarizing the analogical works, one obtains that the coefficient C is also approximately linearly related with normalized flame radius, r/L₁.