Can anyone guide me on modeling the vanes on a francis vane impeller?  I am at a loss how to get the compound curvature surface to have the correct angle relative to the flow direction, particularly in the eye of the impeller.  I can generate the angle relative to the flow that I want at the inlet (as a function of radial position within the eye) and how that varies along the streamline, but taking that and turning it into a vane has me stumped.

thanks

Greg