|Fig. 3-12 A typical rotor blade showing|
27. The stator vanes are again of airfoil section and are secured into the compressor casing or into stator vane retaining rings, which are themselves secured to the casing (fig. 3-13). The vanes are often assembled in segments in the front stages and may be shrouded at their inner ends to minimize the vibrational effect of flow variations on the longer vanes. It is also necessary to lock the stator vanes in such a manner that they will not rotate around the casing.
28. Each stage of a multi-stage compressor possesses
certain airflow characteristics that are dissimilar from those of its neighbour; thus to design a workable and efficient compressor, the characteristics of each stage must be carefully matched. This is a relatively simple process to implement for one set of conditions (design mass flow, pressure ratio and rotational speed), but is much more difficult when reasonable matching is to be retained with the compressor operating over a wide range of conditions such as an aircraft engine encounters.
|Fig. 3-14 Limits of stable airflow.|
|Fig. 3-13 Methods of securing vanes to compressor casing.|