Energy- and Aerodynamic Examination of Slightly Backward Leaning Impeller Blading of Small Centrifugal Compressors

Last decade, turbochargers with maximum 50-60 mm diameter, are more and more frequently designed with slightly backward leaning impeller blading. These kind of impeller blading, comparing to the radial blading, produces higher stress and assuming the same compressor pressure ratio it needs higher tangential speed due to the impeller exit flow slip (hereafter slip). These two disadvantages are surely compensated by some kind of thermal or aerodynamic advantages. By the authors’ examination, using backward leaning impeller blading, the disadvantages are compensated by the small, but the definite increase of compressor efficiency and the positive effect on compressor characteristics.This paper, examining and comparing the above- mentioned advantages and disadvantages, tries to clear the reasons of this design trend and hopefully contributes to the further improvement of these compressors