Combustion Science and Technology, Vol.177, No.7, 1273-1289, 2005
Variation of turbulent burning rate of methane, methanol, and iso-octane air mixtures with equivalence ratio at elevated pressure
Turbulent burning velocities for premixed methane, methanol, and iso-octane/ air mixtures have been experimentally determined for an rms turbulent velocity of 2m/ s and pressure of 0.5 MPa for a wide range of equivalence ratios. Turbulent burning velocity data were derived using high- speed schlieren photography and transient pressure recording; measurements were processed to yield a turbulent mass rate burning velocity, u(tr). The consistency between the values derived using the two techniques, for all fuels for both fuel-lean and fuel- rich mixtures, was good. Laminar burning measurements were made at the same pressure, temperature, and equivalence ratios as the turbulent cases and laminar burning velocities and Markstein numbers were determined. The equivalence ratio (phi) for peak turbulent burning velocity proved not always coincident with that for laminar burning velocity for the same fuel; for isooctane, the turbulent burning velocity unexpectedly remained high over the range phi = 1 to 2. The ratio of turbulent to laminar burning velocity proved remarkably high for very rich iso-octane= air and lean methane/ air mixtures.
Keywords:equivalence ratio;premixed turbulent combustion;turbulent burning velocity;laminar burning velocity;Markstein number