Diffuser arrangement

Abstract

A diffuser arrangement through which a fluid may flow is provided. The diffuser includes an outer diffuser comprising an inner surface, and a flow-guiding device, which is configured such that at least part of the boundary layer flow forming on the inner surface of the outer diffuser can be accelerated in the main flow direction, so that a flow separation is prevented on the inner surface of the outer diffuser. Also provided are an exhaust steam plenum of a steam turbine and an exhaust gas plenum of a gas turbine, both including a diffuser arrangement.

1 .- 12 . (canceled) 
   
   
       13 . A diffuser arrangement which is exposed to a throughflow by a fluid, comprising:
 an outer diffuser including an inner surface; and   a stationary flow-guiding device, the flow-guiding device extending inside the outer diffuser,   wherein a first length of the flow-guiding device lies in a range between 5% to 40% of a second length of the outer diffuser in the main flow direction, and   wherein the flow-guiding device may be used as a flow-accelerating device whereby a first outer surface of the flow-guiding device, which faces a second inner surface of the outer diffuser, and a section of the second inner surface foams a nozzle passage with the result that at least some of a boundary layer flow which develops on the second inner surface may be accelerated in the main flow direction so that a flow separation on the second inner surface is prevented.   
   
   
       14 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the flow-guiding device includes a leading edge which is exposed to an inflow of the fluid and a trailing edge which lies opposite the leading edge and on which the fluid flows off,   wherein an inlet cross section is located between the second inner surface and the leading edge, and an outlet cross section is located between the second inner surface and the trailing edge, and   wherein a first cross-sectional area of the inlet cross section is greater than a second cross-sectional area of the outlet cross section.   
   
   
       15 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the flow-guiding device includes a first inner surface, facing away from the first outer surface, and by the first inner surface an inner diffuser is formed through which the fluid flows and may be decelerated in the main flow direction.   
   
   
       16 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the outer diffuser and the flow-guiding device are axially symmetrically formed and are concentrically arranged around a common symmetry axis.   
   
   
       17 . The diffuser arrangement as claimed in  claim 13 , wherein the nozzle passage is formed as an annular passage. 
   
   
       18 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the flow-guiding device is formed as a straight guide plate which is oblong in a longitudinal section or the flow-guiding device is aerodynamically profiled.   
   
   
       19 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the flow-guiding device is arranged in the range between 80% to 100% of a passage radius of the outer diffuser.   
   
   
       20 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the flow-guiding device is arranged in a region of the inlet cross section of the outer diffuser.   
   
   
       21 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the outer diffuser is formed as an essentially straight diffuser.   
   
   
       22 . The diffuser arrangement as claimed in  claim 13 ,
 wherein the flow-guiding device is pivotably mounted relative to the main flow direction.   
   
   
       23 . An exhaust steam plenum of a steam turbine, comprising:
 a diffuser arrangement, comprising:
 an outer diffuser including an inner surface, and 
 a stationary flow-guiding device, the flow-guiding device extending inside the outer diffuser, 
   wherein a first length of the flow-guiding device lies in a range between 5% to 40% of a second length of the outer diffuser in the main flow direction, and   wherein the flow-guiding device may be used as a flow-accelerating device whereby a first outer surface of the flow-guiding device, which faces a second inner surface of the outer diffuser, and a section of the second inner surface fauns a nozzle passage with the result that at least some of a boundary layer flow which develops on the second inner surface may be accelerated in the main flow direction so that a flow separation on the second inner surface is prevented.   
   
   
       24 . The exhaust steam plenum of a steam turbine as claimed in  claim 23 ,
 wherein the flow-guiding device includes a leading edge which is exposed to an inflow of the fluid and a trailing edge which lies opposite the leading edge and on which the fluid flows off,   wherein an inlet cross section is located between the second inner surface and the leading edge, and an outlet cross section is located between the second inner surface and the trailing edge, and   wherein a first cross-sectional area of the inlet cross section is greater than a second cross-sectional area of the outlet cross section.   
   
   
       25 . The exhaust steam plenum of a steam turbine as claimed in  claim 23 ,
 wherein the flow-guiding device includes a first inner surface, facing away from the first outer surface, and by the first inner surface an inner diffuser is formed through which the fluid flows and may be decelerated in the main flow direction.   
   
   
       26 . The exhaust steam plenum of a steam turbine as claimed in  claim 23 ,
 wherein the outer diffuser and the flow-guiding device are axially symmetrically formed and are concentrically arranged around a common symmetry axis.   
   
   
       27 . The exhaust steam plenum of a steam turbine as claimed in  claim 23 , wherein the nozzle passage is foamed as an annular passage. 
   
   
       28 . An exhaust gas plenum of a gas turbine, comprising:
 a diffuser arrangement, comprising:
 an outer diffuser including an inner surface, and 
 a stationary flow-guiding device, the flow-guiding device extending inside the outer diffuser, 
   wherein a first length of the flow-guiding device lies in a range between 5% to 40% of a second length of the outer diffuser in the main flow direction, and   wherein the flow-guiding device may be used as a flow-accelerating device whereby a first outer surface of the flow-guiding device, which faces a second inner surface of the outer diffuser, and a section of the second inner surface forms a nozzle passage with the result that at least some of a boundary layer flow which develops on the second inner surface may be accelerated in the main flow direction so that a flow separation on the second inner surface is prevented.   
   
   
       29 . The exhaust gas plenum of a gas turbine as claimed in  claim 28 ,
 wherein the flow-guiding device includes a leading edge which is exposed to an inflow of the fluid and a trailing edge which lies opposite the leading edge and on which the fluid flows off,   wherein an inlet cross section is located between the second inner surface and the leading edge, and an outlet cross section is located between the second inner surface and the trailing edge, and   wherein a first cross-sectional area of the inlet cross section is greater than a second cross-sectional area of the outlet cross section.   
   
   
       30 . The exhaust gas plenum of a gas turbine as claimed in  claim 28 ,
 wherein the flow-guiding device includes a first inner surface, facing away from the first outer surface, and by the first inner surface an inner diffuser is formed through which the fluid flows and may be decelerated in the main flow direction.   
   
   
       31 . The exhaust gas plenum of a gas turbine as claimed in  claim 28 ,
 wherein the outer diffuser and the flow-guiding device are axially symmetrically formed and are concentrically arranged around a common symmetry axis.   
   
   
       32 . The exhaust gas plenum of a gas turbine as claimed in  claim 28 , wherein the nozzle passage is formed as an annular passage.