Machining of turbulated cooling channel holes in turbine blades

Whilst the introduction of turbulators in cooling channels improves the cooling efficiency, it makes the machining of the channels with a shaped tube electrolytic machining (STEM) drill in a single pass difficult. This paper describes an algorithm to model the machining of a given turbulator shape by changing the feed rate at regular intervals. This algorithm is iterative and relies on predicting the workpiece shape using the boundary element method (BEM) at each stage of the analysis. The algorithm is verified by comparing the predicted and machined shapes of a turbulator; it is shown that the resulting accuracy is good.