added disk-velocity hack for BladedFF.
added disk-velocity hack for BladedFF.

git-svn-id: 8364067d7f169cd7bffa284e908e01e4e4de2b00@170 96535b8f-fecd-4773-a067-ac893715d582

OpenFAST/OpenFAST,OpenFAST/OpenFAST,OpenFAST/OpenFAST