Distribution of OH and CH Radicals in the Boundary Layer with Ethanol Combustion

The influence of free-stream turbulence on the distributions of CH and OH radicals is studied with the use of optical methods of measurements in focused beams. The data on CH concentration are obtained for the minimum level of turbulence, and the OH concentration profiles are obtained for three levels of velocity fluctuations: 1, 8, and 18. It is shown that the regions where the OH and CH radicals are observed in the laminar boundary layer are shifted from the temperature maximum toward the oxidizer zone and toward the fuel zone, respectively. The highest level of the OH concentration is close to values typical of hydrogen combustion. The root-mean-square fluctuations of velocity and the mean values of the OH concentration vary nonmonotonically along the flame.