A technique is described for the analytical representation of the geometry of radial a~ld mixed flow compressor impellers constructed of radial or non-radial blade elements. A similar analytical expression is used to describe the hub, shroud, and camberline curves; if required, the angle of inclination of the blade elements from the radial direction is also described. These analytical expressions lend themselves to rapid manipulation, enabling the designer to apply established two-and three-dimensional fluid dynamic analysis procedures to a wide range of possible design configurations.
The analytical expressions completely specify the impeller passage geometry from which computer graphics output can be obtained to give isometric, plan and side views of the impeller. For manufacturing, the computer graphics subroutine supplies a series of flow passage sectiom on a large scale at any number of axial stations specified by the designer. These passage sections are used in the construction of templates from which the impeller is manufactured using copy milling techniques. The analytical specification also gives a detailed co-ordinate specification of the impeller for use with numerically controlled machines.