Diffuser, in particular for an axial flow machine

Abstract

A diffuser for an axial flow machine has a transition from a ring channel having a first cross sectional area into an outlet space with a second, larger cross sectional area along a machine axis of the axial flow machine. The transition includes a plurality of steps.

What is claimed is: 
     
         1 . A diffuser for an axial flow machine comprising a transition from a ring channel having a first cross sectional area into an outlet space with a second, larger cross sectional area along a machine axis of the axial flow machine, wherein the transition includes a plurality of steps. 
     
     
         2 . The diffuser as recited in  claim 1 , wherein the axial flow machine is a stationary gas turbine, the diffuser being disposed in the stationary gas turbine. 
     
     
         3 . The diffuser as recited in  claim 2 , wherein the diffuser is disposed at an outlet of the stationary gas turbine. 
     
     
         4 . The diffuser as recited in  claim 1 , wherein the plurality of steps is two steps, the two steps increasing the cross sectional area inside the diffuser from the first to the second cross sectional area. 
     
     
         5 . The diffuser as recited in  claim 1 , wherein the diffuser is configured as a Carnot diffuser. 
     
     
         6 . The diffuser as recited in  claim 1 , wherein the diffuser includes an outer casing and an inner casing configured to allow a medium to flow therebetween during operation, the plurality of steps being formed by steps in a diameter of the inner casing. 
     
     
         7 . The diffuser as recited in  claim 1 , further comprising a ring-shaped, convexly curved guiding surface which tapers in diameter disposed between two adjacent steps of the plurality of step, and an annular passage disposed at an upstream step of the two adjacent steps configured to allow a gas flow to emerge and flow along the guiding surface in the form of a Coanda flow. 
     
     
         8 . The diffuser as recited in  claim 7 , wherein the two adjacent steps are a penultimate step and a last step of the diffuser.