Y-Grid and turbine blades

Vitali

Hi experts!

1. somebody can me explain, what is it Y-Grid and how can I create it at the end of turbine blade?

2. I need in my task create a mesh for two turbine stages including blades, coasing and shuft (turbine segment). I do conjugate heat transfer simulation and so the mesh must be generate inside blade (solid) also. If I use only O-Block around the blade, I get problems this mesh quality in region of blades edges. Is somebody did similar topic? What is the best blocking strategy for tubines geometry?

For every advice and comments I thank in advance!