The variation in flame temperature with burner stabilization in 1-D premixed dimethyl ether/air flames measured by spontaneous Raman scattering

The flame temperatures in flat, laminar premixed dimethyl ether (DME)/air flames with varying degrees of burner stabilization were measured by spontaneous Raman scattering in a range of equivalence ratio (φ) from 0.6 to 2.0. Three commonly used mechanisms to describe DME oxidation were evaluated by comparing the calculated variation of flame temperature derived from one-dimensional flame calculations as a function of DME/air exit velocity with those obtained from the measurements. The results showed the necessity of incorporating radiative heat losses in the flame calculations. The three mechanisms yield similar results at φ = 0.6 and 2.0, underpredicting the temperatures more than 30 K. Differences between the measured and predicted temperatures for burner-stabilized flames are seen to indicate whether a free-flame burning velocity (SL) is too high or too low. The results suggest a free-flame burning velocity of ∼14 cm/s at φ = 0.6, 2 cm/s lower than the mechanisms predicted, and burning velocities close...