Heat transfer to a row of impinging jets in consideration of optimization

In the current study the heated-thin-foil technique is used jointly with infrared thermography to evaluate accurately the heat transfer characteristics of one row of jets impinging on a flat plate. The impingement is confined by the test section and spent air is constrained to exit in only one direction. The configuration and parameters variation range are similar to those encountered in turbine internal cooling systems. The results are analysed in terms of local and averaged Nusselt number keeping in mind the design engineer preoccupation of minimizing the amount of cooling air taken from the compressor. The influence of the impingement distance Z/d, injection Reynolds number Re and spanwise spacing p/d between two holes of the row is presented. An optimum impingement distance is pointed out and some qualitative design rules for the two other parameters are underlined.