This article is devoted to the analysis of the results of mathematical modeling, and experimental investigations of the structure of a turbulent flame arising from the combustion of diesel fuel. A estimation of the turbulence scale in a diffusion flame by using infrared thermography and the fast Fourier transform (FFT) approach by temperature spectra was carried out. Flow field was modeled by using Reynolds-averaged Navier–Stokes (RANS) equations. The turbulence characteristics have been determined by the Menter Shear Stress Transport (SST model). The heat balance, diffusion, and chemical reactions are described by the heat-transfer and mass-balance equations. The chemical reaction in the laminar flow is determined by the Arrhenius kinetics. For fully developed turbulence combustion was modeled on the basis of eddy dissipation model. In the intermediate regime when turbulence intensity is small takes into account the influence of turbulent pulsations on combustion rate. The comparison results of numerical modeling and experimental investigation show a good match between the parameters of flame turbulence structure. Results of investigation demonstrate that in the initial part of the flame near the fuel surface appear turbulent temperature pulsations, but the gas flow and combustion occur in a laminar mode with curved streamlines. Turbulent combustion in the basic area of the flame on the outer jet boundary occurs in the regime of micro-volume burning.