The Laminar Boundary Layer on a Rotating Blade

Boundary-layer equations of motion for a blade rotating steadily in an incompressible fluid are developed. The equations show that , at stations several chord lengths from the axis of rotation of a thin blade, the chordwise velocity is independent of the spanwise velocity due to rotation; hence, the separation line is unaffected by rotation. The detailed calculation of the spanwise velocity distribution in the boundary layer is carried out for two examples. Spanwise velocities in the boundary layer are found to be small compared with chordwise velocities. No large effects of rotation are found.