with the researching, developing and manufacturing to big-sized
compressors with the flow up to 50–100 thousand M3 per minute,
the structure of the compressors has greatly changed. Varied techniqueand technology such as compact and convenience to assembly and commissioning, easiness to manufacturing are widely used. The complicated parts,such as impellers with curvic coupling of transmitting big torque, also widely used. The impellers are most madeof aluminum alloy. They are forged and heat-treated. A few
centrifugal impellers of small-sized engines are cast by titanium
alloy. A impeller locates on the impeller shaft of the compressor and driven by the shaft through the curvic coupling. It automatically
secures alighning under conditions of the radial deformation of the
impeller because of being heated or acted by centrifugal load.