Heat and mass transfer problems for film cooling

In the paper, a review of calculation methods and of experimental results f or heat transfer under film cooling is presented. The effects of arrangemen t of film cooling, longitudinal pressure gradient, nonisothermality and com pressibility of the gas, injection of a foreign gas, surface roughness, swi rling of flow, and turbulent pulsations of the main gas flow on the effecti veness of film cooling are considered. A generalized correlation for the ef fectiveness of film cooling, is proposed, which makes it possible to take i nto account the influence of the above factors. It is shown, that in determ ination of the heat transfer coefficient in the region of film cooling, it is necessary to take into account the influence of injected gas on the deve lopment of the thermal boundary layer. A method of calculation for combined cooling (film, porous or transpiration and convective), which accounts for effect of longitudinal hear conductivity of the wall on the film cooling e ffectiveness is proposed. An estimation of profile losses on a gas turbine blade is given for the cases of film and porous or transpiration cooling.