Aerodynamics of centrifugal compressors: An examination of the geometry of radial diffusers

An analytic method of subsonic radial diffuser design is proposed and investigated, wherein the passages are designed to yield a fixed equivalent diffuser angle or rate of area increase. It is demonstrated in the two dimensional case that much more rapid diffusion can be achieved than with a vaneless diffuser. Existing correlations of acceptable diffusion limits of straight-walled diffusers are combined with this purely geometric design method to generate optimum diffusers, assuming that the slight curvature of the passages does not appreciably affect the diffuser performance.