Comparative Study between Different Design Methodologies for Centrifugal Compressor Impellers

The detailed shape of any centrifugal impeller channels may be determined by using either of two general approaches, namely the direct and the indirect design approach. A radial flow centrifugal impeller that satisfies specified duties has been designed for a prescribed space rate of deceleration using the direct approach- The same duty has also been met by an impeller designed using the indirect approach (both impellers have the same principal dimensions). For the sake of comparison, provision has been made regarding the impeller that was designed using the indirect procedure to ensure a resulting rate of deceleration similar to the prescribed schedule for the direct approach. This was achieved by systematic adjustments of the detailed geometry of the impeller.

It does seem that the direct approach is less time consuming and less expensive in terms of computational costs than the indirect approach. Furthermore, the direct approach does not require great designer experience compared with the indirect approach, since the successful application of the latter depends very largely on the experience and the engineering judgement of the designer.