4. Kinematic properties of flat blade grids

The flat blade grid, the starting point for axial turbomachinery, has been the subject of numerous theoretical and experimental studies. The aim of these studies is to provide a satisfactory solution to two typical problems: the direct problem and the inverse problem:

– direct problem: for a given grid, what is the output angle for a given input angle? This is the problem we have to tackle to establish the predictive characteristic curve of an existing machine;

– inverse problem: to ensure a given output angle under a given input angle too, what is the best grid to use; in other words, what is the best-suited triplet (C _z∞0 , σ, γ )? This is the type of problem the designer has to deal with when designing a machine.