Abstract: The essential difference of the turbulent state in the mixing layer contributes to the totally different behavior of the cooling and wall friction reduction performances of the hydrogen and hydrocarbon fuel films. The turbulent transport processes between the hydrogen film and the mainstream are much weaker than that of the hydrocarbon film making inert hydrogen to be rather superior in cooling and friction reduction applications. However, the film cooling performance severely deteriorates when the hydrogen film burns due to the severe heat release sources presented near the wall. On the other hand, the boundary layer combustion of hydrocarbon film can remarkably improve its original barely satisfactory cooling and friction reduction performance to be comparable to that of the hydrogen film due to the suppression of turbulent transport processes in the mixing layer and presence of heat absorption sources near the wall.