Method and apparatus for reducing total pressure loss in a turbine engine

Abstract

A method and apparatus for reducing total pressure loss in the exhaust of a combustion device via an axial diffuser having no turning vanes, support struts, rods, or other obstructions to exhaust flow. The axial diffuser includes an inner wall and an outer wall each having a turn radius and forming an annular cross section having increasing cross-sectional area in the downstream direction of flow, the flow being transitioned from axial to radial direction thereby. The diffuser is supported in the plenum by rods, struts or a cradle; from a stand surrounding the axial diffuser via struts or rods; or from existing diffuser support structure by web stiffeners. The diffuser flow path turn radius of the outer wall ranges from about 50-95% of the radial distance from the inner wall to a wall of the exhaust plenum, and of the inner wall ranges from about 10-70% of this distance.

1 . An axial diffuser, comprising: 
 an inner wall connected to an exhaust plenum, the inner wall having an inner wall radius turn;    an outer wall having an outer wall radius turn; and    a support mechanism supporting the outer wall;    wherein the inner wall and the outer wall form a flow path free of turning vanes.    
   
   
       2 . The diffuser of  claim 1 , wherein has a circular cross-sectional shape.  
   
   
       3 . The diffuser of  claim 2 , wherein the inner wall has an opening, and wherein a shaft is receivable in the inner wall opening in a direction along a centerline within the opening in the inner wall.  
   
   
       4 . The diffuser of  claim 3 , wherein the inner wall includes a first inner wall portion, the first inner wall portion extending in a direction generally parallel to the centerline.  
   
   
       5 . The diffuser of  claim 1 , wherein the outer wall radius turn is a large radius turn.  
   
   
       6 . The diffuser of  claim 5 , wherein the large radius turn of the inner wall has a radius between about 50% and 95% of a perpendicular distance from the first inner wall portion to a wall of the exhaust plenum.  
   
   
       7 . The diffuser of  claim 6 , wherein the perpendicular distance is a minimum.  
   
   
       8 . The diffuser of  claim 1 , wherein the outer wall has a circular cross-sectional shape.  
   
   
       9 . The diffuser of  claim 6 , wherein the outer wall radius turn is a large radius turn.  
   
   
       10 . The diffuser of  claim 9 , wherein the large radius turn of the inner wall has a radius between about 10% and 70% of the radius of the outer radial turn.  
   
   
       11 . The diffuser of  claim 1 , wherein the support mechanism comprises a connection between a wall of the exhaust plenum and the outer wall.  
   
   
       12 . The diffuser of  claim 11 , wherein the connection comprises one selected from a group consisting of rods, struts, or a cradle.  
   
   
       13 . The diffuser of  claim 11 , wherein the connection comprises a stand surrounding the axial diffuser.  
   
   
       14 . The diffuser of  claim 11 , wherein the connection comprises at least one web stiffener attached to a wall of the axial diffuser.  
   
   
       15 . The diffuser of  claim 1 , wherein the support mechanism is external to the flow path.  
   
   
       16 . The diffuser of  claim 1 , wherein the support mechanism comprises an extension from turbine.  
   
   
       17 . The diffuser of  claim 1 , wherein the cross-sectional area of the flow path increases in size in a downstream direction of exhaust flow through the flow path.  
   
   
       18 . The diffuser of  claim 3 , wherein the cross-sectional area of the flow path increases in size in a downstream direction of exhaust flow through the flow path, and wherein the shaft is a rotor shaft.  
   
   
       19 . The diffuser of  claim 18 , wherein the rotor shaft is rotated by the exhaust flow.  
   
   
       20 . The diffuser of  claim 19 , wherein the rotor has at least one attached blade.  
   
   
       21 . The diffuser of  claim 1 , wherein the inner wall radius turn is concentric with the outer wall radius turn.  
   
   
       22 . The diffuser of  claim 1 , wherein the flow path is unobstructed by at least one selected from a group consisting of radial turning vanes, support struts, and rods.  
   
   
       23 . The diffuser of  claim 1 , wherein the annular flow path transitions the exhaust flow from an axial direction to a radial direction.  
   
   
       24 . The diffuser of  claim 1 , wherein the flow path has a generally annular cross-sectional shape.  
   
   
       25 . An axial diffuser for a combustion device exhaust component, the exhaust component including an exhaust plenum having at least a first plenum wall and a second plenum wall, the diffuser comprising: 
 an outer diffuser wall having a circular cross-sectional shape;    an inner diffuser wall attached to the first plenum wall, the inner diffuser having a circular cross-sectional shape and an inner opening, wherein the inner diffuser wall is situated such that the inner diffuser wall and the outer diffuser wall form a flow path therebetween, the flow path being unobstructed by turning vanes.    
   
   
       26 . The axial diffuser of  claim 25 , wherein the flow path has a generally annular cross-sectional shape and cross-sectional area, the area of the annular cross-sectional area increasing with downstream direction of exhaust flow in the flow path  
   
   
       27 . The axial diffuser of  claim 25 , further comprising: 
 a rotor extending through the inner opening of the inner diffuser wall.    
   
   
       28 . The diffuser of  claim 26 , wherein the inner wall includes a first inner wall portion and a second inner wall portion, the second inner wall portion including a radius turn.  
   
   
       29 . The axial diffuser of  claim 28 , wherein the radius turn of the inner wall is a large radius turn having a radius between about 50% and 95% of a perpendicular distance from the first inner wall portion to the second plenum wall.  
   
   
       30 . The diffuser of  claim 28 , wherein the outer wall includes a radius turn.  
   
   
       31 . The diffuser of  claim 30 , wherein the inner wall radius turn and the outer wall radius turn cooperate to transition the exhaust flow from an axial direction to a radial direction.  
   
   
       32 . The diffuser of  claim 29 , wherein the outer wall includes a large radius turn, the large radius turn of the inner wall having a radius between about 10% and 70% of radius turn of the inner wall large radius turn.  
   
   
       33 . A method for reducing total pressure loss in the exhaust flow of a combustion device having an exhaust plenum, the method comprising: 
 forming a flow path unobstructed by turning vanes, the flow path being located within an axial diffuser in the exhaust plenum, wherein the flow path has an increasing cross-sectional area in downstream direction of flow therethrough, wherein the axial diffuser includes an inner wall having a radius turn and an outer wall having a radius turn, the inner wall being attached to a wall of the exhaust plenum and the outer wall being attached to the exhaust plenum via a support mechanism external to the flow path;    transmitting the exhaust flow through the axial diffuser; and    transitioning the exhaust flow from an axial direction to a radial direction.