High Resolution Experimental and Computational Methods for Modelling Multiple Row Effusion Cooling Performance

Abstract

The continuing rise in turbine entry temperatures has necessitated the development of evermore advanced cooling techniques. Effusion cooling, which is characterised by a high density of film holes operating at low blowing ratios, represents one possible mechanism for achieving high overall cooling effectiveness. This paper presents an experimental investigation performed on flat-plate, effusion-type cooling geometries (with primary hole pitches of 3.0D and 5.75D) using pressure sensitive paint to yield high-resolution film effectiveness distributions using the heat/mass transfer analogy. CFD was used to model the setup computationally, with results comparing favourably to the experiments. The CFD domain was then altered to model a single hole. A superposition method was developed and applied to the two dimensional film effectiveness distribution, yielding data for an array of closely-packed holes. The method produced satisfactory results at higher pitches, but at lower pitches, high levels of jet interactions reduced the performance of the superposition method.