Effect of free-stream turbulence on the boundary-layer structure with diffusion combustion of ethanol

The effect of turbulization of a subsonic air flow on the boundary-layer structure was experimentally studied during evaporation and combustion of ethanol behind an obstacle 3–6 mm high. It is shown that turbulization increases the thermal boundary-layer thickness by a factor of 2, where as the dynamic boundary-layer thickness changes weakly. For 1–18% turbulence at the entrance, the change in the momentum thickness along the channel is close to the change in the momentum thickness for a laminar isothermal boundary layer without injection. Local regions of elevated turbulence with a high intensity of heat and mass transfer arise in the case of combustion behind the obstacle at a distance of 40–50 obstacle heights.