The Public 777 Shaped Hole

Gas turbines utilize film cooling on hot gas path components to increase life by lowering metal temperatures.  Cylindrical film cooling holes are the most economical to manufacture, but shaped holes have become widely used in today’s turbines resulting from better cooling performance than cylindrical holes.  While there are many different shaped hole designs in literature, there are few geometries common between publications of different researchers. 

To assess the performance of different cooling hole geometries, a baseline is needed to compare with.  Our lab has developed a film-cooling geometry that has been widely accepted by industry, universities, and government labs as a baseline, shaped film-cooling hole.  The hole is known as the 7-7-7 film cooling hole as a result of its expansion angles as shown below.   A significant amount of data is available for the 7-7-7 shaped film-cooling hole, which can be used to compare with for numerical predictions or the performance of other film-cooling hole geometries.