Design and optimization of meridional profiles for the impeller of centrifugal compressors

An impeller design for radial flow compressors is addressed in several text books. According to practiced methods, the overall dimensions and properties of an impeller can be determined using basic aerodynamic and thermodynamic relations. However, the values of several parameters and geometric details have not been strictly assigned. Hence, the experience and empirical relations of designers are important. The impeller meridional profile is an important detail that has a significant influence on the performance of the impeller. Generally, circular arc curves are implemented for this purpose. In this study, the effect of using elliptic curves is studied and compared with circular curves. An experimentally validated numerical code is used for this investigation. Two different compressors are studied to formulate the conclusion. Results show that elliptic curves can be a better initial choice for hub and shroud profiles compared with the commonly used circular arc. Smoother direction change with less secondary flow and related loss are identified as the improvement cause.