Bunsen flame hydrodynamics

An investigation into the structure of premixed Bunsen flames was performed to determine whether by using laser velocimetry an unambiguous means of measuring laminar flame speed could be devised and to provide data by which theoreticians could critically evaluate their predictions. Data presented for the former include the axisymmetric flow field and a comparison of cone angles obtained from direct and schlieren photographs of the flame. Data presented for the latter include, for varying equivalence ratios and cone angles, the radius of curvature of the tip and change in velocity through the tip. The centerline velocity was found to decay as a function of axial distance, and a noncoincidence of schlieren and luminous surfaces was observed. When normalized by a preheat thickness (based on the harmonic mean of the thermal conductivity), the behavior of the radius of curvature of the tip compared well with a recent theoretical prediction.