Arcam AB fka AMAVF

[Tom Joad]

Yes. Turbine blades should have a smooth finish for at least two reasons: the boundary layer problem in fluid mechanics, and to reduce the chance that a crack starts at a surface crevice. If the surface is rough the boundary layers at and near the blade surface have no chance of developing laminar flow and every chance of creating more turbulence. Efficiency goes down as turbulence increases. Stresses at a surface crevice are concentrated at the crevice so cracks start much more easily at those locations.