Centrifugal Stresses in Impellers

THE importance of the aircraft engine supercharger is being emphasized by the increasing demands for high altitude performance in the present war. Centrifugal stresses of considerable magnitude are induced in the supercharger impeller by reason of the high rotative speeds necessary to obtain the desired pumping effect. A speed of 20,000 r.p.m. is not uncommon for an impeller of 12 in. outside diameter and over. Consequently, a knowledge of the centrifugal stresses constitutes a basic design consideration. Unfortunately, a direct determination of these stresses is not an easy matter.