Turbulent burning velocity, burned gas distribution, and associated flame surface definition

Burning Rate in Impinging Jet Flames

“…It is of interest to note that, as shown elsewhere [12], the above purely theoretical results are very close to the definition of the burning velocity of expanding statistically spherical premixed turbulent flames, proposed by Bradley et al [11] based on different reasoning.…”

“…Several methods have been proposed to resolve the above issues and to determine turbulent flame speed S t and/or burning velocity U t in statistically stationary [5,6] or expanding [10][11][12] flames. In particular, in [10], an expanding statistically spherical premixed turbulent flame with a self-similar mean structure (i.e., the mean density ρ(ξ) depends on a single normalized distance ξ = [r − R f (t)]/Δ t (t), rather than on two independent variables, time t and radial distance r) was theoretically studied and the following two radii:…”

Turbulent burning rates of methane and methane–hydrogen mixtures

“…The flames were imaged using high speed schlieren photography. Simultaneous laser sheet and schlieren measurements have been performed in the same vessel [7] for propane flames where it was demonstrated that the flame brush thickness continually increased (for all the flames monitored) from ignition till they passed beyond the windows. These earlier studies suggested that it was possible to determine the mass rate of burning, related to the turbulent burning velocity, u tr , on the basis of high speed schlieren photography:…”

Flame front analysis of ethanol, butanol, iso-octane and gasoline in a spark-ignition engine using laser tomography and integral length scale measurements

“…In contrast, Lewis numbers smaller than unity (deficient reactant mass transfer greater than heat transfer) are susceptible to intensify instabilities, as the flame speed increases for stronger stretched regions and the velocities at the crests of flame wrinkles should be higher than at the cusps. More details on the calculation of the Lewis number and its effect on laminar and turbulent flame speeds can be found in [73][74][75][76][77][78]. For calculating the Lewis number of the single component fuels used in this study (ethanol, butanol and isooctane) and at the engine's thermodynamic conditions at ignition timing, values of specific heats, thermal conductivity, density and viscosity of the mixtures, as well as diffusion coefficients, were required.…”

“…These were taken from [79][80][81]; gasoline was exempted from this exercise due to lack of all necessary thermophysical properties. The binary diffusion coefficient for Le was based on either oxygen or the fuel as deficient reactants to produce 'lean' and 'rich' values, while the equivalent 'stoichiometric' value was based on the average of these two values following the methodology adopted by Bradley and co-workers [73][74][75][76].…”