Vaned diffusers may considerably improve the performance of centrifugal compressor stages. The paper addresses the question how modifications of the vane profile shape in the leading edge (LE) region will affect the diffuser performance and to what extent the improvements depend on the diffuser configuration. The standard vanes have a semicircular LE profile. Various results of steady-state numerical investigations are presented. The 3D flow field has been computed with a commercial Navier-Stokes code (TASCflow, AEA Technology plc) using for the simulations diffuser inflow (i.e. impeller outflow) boundary conditions obtained by measurements and applied for different leading edge shapes of the vanes. The leading edge redesign is based on MISES (MIT), a 2D analysis and inverse-design software package. The standard and redesigned diffusers are evaluated and compared for two blade stagger angles.
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