Investigation of flame and burner plate interaction during the heat flux method used for laminar burning velocity measurement

Abstract

The heat flux method has been used widely for measuring the laminar burning velocity SL. However, compared with ideal SL definition of freely-propagating, stretch-less and adiabatic, the data obtained by the heat flux method is usually not perfectly freely-propagating due to the interaction between the flame and burner plate, which can affect the accuracy of the measurement. Though this issue has caught attention by some researchers, it hasn’t been evaluated extensively by experiments so far. To fill this gap, this study specially investigated four experimentally obtained factors: the measured burning velocity, the measurement sensitivity, the stand-off distance and the flame thickness. The experiments were carried out with methane + air flames at 1 atm and 298 K, equivalence ratio 0.7–1.5. By changing the burner plate temperature, the extent of flame and burner plate interaction can be well controlled. After series of assumption, deduction, and comparison with experiment results, a half-quantitative equation was proposed, and the burning velocity of stretch-less adiabatic freely-propagating flame was extrapolated from the non-freely propagating experiment results, which shows good agreement with literature data and simulation results. Besides, the uncertainty caused by not considering the flame and burner plate interaction was also evaluated.