Application of the swollen polymer technique to the study of heat transfer on film cooled surfces

The application to film cooling situations of a relatively novel technique for the determination of the spatial variation of local heat transfer coefficient is described. The technique makes use of the heat-mass transfer analogy. The mass transferring system consists of a coating of an involatile silicone rubber polymer swollen in a volatile organic fluid. The rate of change of the swollen polymer coating thickness due to the influence of the film cooling airflows is proportional to the mass transfer coefficient and is measured precisely by the technique to laser holographic interferometry. The capability of the technique is providing a wealth of information and detail is demonstrated in this paper for the case of film cooling through a row of discrete holes.