Flow Investigation in Centrifugal Compressor Diffuser

In a Centrifugal Compressor the work is imparted on the impeller to get higher total pressure of the working fluid.a diffuser is employed at the down stream of the impeller for the conversion of kinetic energy of the flow coming out of the impeller into static pressure.The overall efficiency of the compressor is equally dependent on the good design of both impeller and diffuser.Basically ,diffuser can be classified into two different types,vaneless and vaned diffusers.While the vaneless diffuser consists of smooth walled axisymmeric passage with radial surface with which flow gets diffused before dumping into a downstream collector.Earlier study using Hotwire Anemometer indicates that velocity of the flow at the entry to the diffuser is three dimensional in nature with a good amount of swirl and this has tremendous effect on the performance of down stream diffuser.Hence it was aimed at to investigate separately the nature of flow behaviour in a vaneless diffuser and in a vaned diffuser