Page 37 - The Jet Engine

Compressors

Fig. 3-11 Methods of securing blades to disc.

Rotor blades introduced. The blade extremities appear as if
26. The rotor blades are of airfoil section (fig. 3-12) formed by bending over each corner, hence the term
and usually designed to give a pressure gradient 'end-bend'.
along their length to ensure that the air maintains a
reasonably uniform axial velocity. The higher Stator vanes
27. The stator vanes are again of airfoil section and
pressure towards the tip balances out the centrifugal are secured into the compressor casing or into stator
action of the rotor on the airstream. To obtain these vane retaining rings, which are themselves secured
conditions, it is necessary to 'twist' the blade from to the casing (fig. 3-13). The vanes are often
root to tip to give the correct angle of incidence at assembled in segments in the front stages and may
each point. Air flowing through a compressor creates be shrouded at their inner ends to minimize the
two boundary layers of slow to stagnant air on the vibrational effect of flow variations on the longer
inner and outer walls. In order to compensate for the vanes. It is also necessary to lock the stator vanes in
slow air in the boundary layer a localized increase in such a manner that they will not rotate around the
blade camber both at the blade tip and root has been casing.

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