Method for analysis of showerhead film cooling experiments on highly curved surfaces

The transient liquid crystal technique has been extensively used for measuring the heat transfer characteristics in gas turbine applications. Thereby, the time evolution of the surface temperature is usually evaluated using the model of a semi-infinite flat plate. For experiments on cylinders, Wagner et al. [G. Wagner, M. Kotulla, P. Ott, B. Weigand, J. von Wolfersdorf, The transient liquid crystal technique: influence of surface curvature and finite wall thickness, ASME Paper GT2004-53553, 2004] showed, that curvature and finite thickness effects can have an influence on the obtained heat transfer coefficients. The aim of this study is to develop a time effective data reduction method that accounts for curvature and that is applicable to film cooling experiments with time varying adiabatic wall temperatures. To verify this method, transient liquid crystal experiments have been carried out on a blunt body model with showerhead film cooling. The experimental data was evaluated with the traditional semi-infinite flat plate approach and with the curvature correction using regression analysis.