An Overall Correlation of Film Cooling Effectiveness From One Row of Holes

Film cooling effectiveness of a single row of cylindrical holes on a flat plate was analyzed. It was found, that the flow can be divided into two typical regimes along the downstream distance. Near the ejection location a complex flow domain of cooling film formation with strong 3-D character was recognized. Further downstream a domain of a diluting cooling film with 2-D character was identified. An analytical solution for the film cooling effectiveness along the downstream distance was derived in the 2-D regime. Based on literature data, correlations for the formation length, i.e. the length of the 3-D domain, and the corresponding film cooling effectiveness at the start of the 2-D film were developed. These correlations provide the initial conditions of the analytical solution of the 2-D film flow. A damping function was introduced to connect the two regimes and to model the lateral averaged film cooling effectiveness distribution within the 3-D flow domain. From this, a correlation was established, taking into account the full set of parameters, which was presented in an earlier study [1]. The correlation was tested over a wide range of parameters, and an error estimation is given to demonstrate the quality of the correlation.