Abstract: Airflow exiting a centrifugal compressor is diffused in multiple shaped passages tangential to the compressor impeller dumped into a plenum to reduce its Mach number and then directed through deswirl vanes to the entrance of a combustor. Deswirl at reduced Mach number significantly reduces pressure losses resulting in reduced complexity and manufacturing cost for the diffuser deswirl system.

Abstract: A diffuser provides a transition from a centrifugal compressor to the annular combustion chamber of a gas turbine engine. The diffuser comprises a plurality of linear passages which gradually merge radially outward from a circular cross-section to an outlet having a near rectangular cross-section defined by two flat opposing parallel sides and two opposing curved sides. The two opposing curved sides produce a razor sharp trailing edge which maximizes the diffuser efficiency. The linearity of the diffuser passage allows the diffuser to be manufactured to close tolerances by electric discharge milling an annular plate in a manner which assures uniformity and consistency between diffusers. The near rectangular shape of the outlet of the diffuser passages optimizes flow distribution to the annular combustion chamber. A transition region and deswirler section downstream of the near rectangular outlet may be provided to match the diffuser flow path to the combustor geometry.