Progettazione di giranti centrifughe / Design of centrifugal rotors

The paper discusses single and double curvature centrifugal turbo machine rotor blades which can use a set of profiles, the fundamental characteristics of which were derived from experiments in the wind tunnel of the large experimental laboratory of NACA, now NASA. A criterion is formulated for extending the use of these profiles of four digits to radial flow rotors. The novelty of the method is not in the circumferential design of the profiles but as a plane development of the sections, characteristic of the error triangles method. The results of the numerical investigations, compared with more traditional solutions such as those with multiple arcs of a circle, confirm the efficiency and flexibility of this new procedure. This possibility of adopting profiles of known geometrical configuration has permitted automatic generation of the blade surface, and also further assisted design of even more complex blades such as those of multi-stage machine diffusors.