乱流浮上がり拡散火炎の基部構造に関する実験的検討 : 第2報,火炎基部の拡散火炎片構造(熱工学,内燃機関,動力など)  [in Japanese] An Investigation of Flame Base Structures of Lifted Jet Diffusion Flames : 2nd Report, Diffusion Flamelet Structure at the Lifted Flame Base  [in Japanese]

Flamelet structures of flame bases of turbulent lifted diffusion flames have been investigated experimentally by using the Rayleigh scattering method, which can evaluate two-dimensional temperature fields. Methane/hydrogen mixture was issued from a center tube of 3.2 mm I.D. into a surrounding air flow. Two flames were investigated, of which the Reynolds numbers were 4 200 and 6 700, respectively. Temperature dissipation rates and scalar dissipation rates conditional on the maximum temperature were evaluated from the two-dimensional temperature distributions. It found from the results that probability density functions (PDF's) of flame temperatures of flamelets are close to normal and PDF's of the temperature dissipation rate and scalar dissipation rate are to lognormal. It also found that variances of PDF's of the scalar dissipation rate at the flame base are smaller than values for fully burning turbulent diffusion flames. Moreover, the model for turbulent lifted diffusion flames, which uses the scalar field variable in the flamelet model, has been verified as adequate to express the flamelet structure at the flame base except for treatments of the variance of the scalar dissipation rate and a coefficient C_G related to the brush width.