Patent Publication Number: US-8109099-B2

Title: Flow sleeve with tabbed direct combustion liner cooling air

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a flow sleeve for controlling cooling airflow to an outer periphery of a combustion liner in a gas turbine engine. 
     Gas turbine engines are known, and typically include a compressor section that compresses air and delivers it downstream into a combustion section. The air is mixed with fuel in the combustion section and burned. Products of this combustion pass downstream towards a turbine section, to drive turbine rotors. 
     A combustion sleeve directs the products of combustion from the combustion section downstream toward the turbine rotors. The combustion liner becomes quite hot from the products of combustion. Thus, it is known to provide cooling air to an outer periphery of the combustion liner. 
     A part called a flow sleeve is mounted between an outer housing and the combustion liner, and provided with a plurality of openings. Cooling air is provided radially outwardly of the flow sleeve, and is directed through the holes at the outer periphery of the combustion liner. In this way, the combustion liner is cooled. 
     In one known flow sleeve, a plurality of tubular members extend about the holes, and from an inner periphery, to form conduits for controlling the direction in which the air is moved against the combustion liner. The tubular members add expense, and are complex to manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a combustion liner to receive products of combustion in a gas turbine engine, and deliver the products of combustion downstream toward a turbine rotor. An outer housing is positioned radially outwardly of the combustion liner. A flow sleeve is positioned radially intermediate the outer housing and the combustion liner. The flow sleeve defines a chamber, radially outwardly of the flow sleeve, for receiving cooling air. A plurality of holes extend through the flow sleeve to deliver cooling air against an outer periphery of the combustion liner. A plurality of tabs are associated with at least some of the holes in the flow sleeve, and are positioned to extend radially inwardly on a downstream side of the holes. 
     The tabs control the air flow direction but are less expensive than the prior art. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a cross-sectional view of a combustion duct. 
         FIG. 2  shows a cross-sectional view of a flow sleeve with a tab ring. 
         FIG. 3  is an end view of the  FIG. 2  tab ring. 
         FIG. 4  shows a plan view tab of the  FIG. 2  tab ring. 
         FIG. 5  shows a cross-sectional partial view of the flow sleeve and cooling tabs. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A combustion duct  20  for use in a gas turbine engine is illustrated in  FIG. 1 . An outer housing  22  connects to a downstream duct  24  leading to a turbine section (not shown). Outer housing  22  also surrounds a combustion liner  31 . Combustion liner  31  receives products of combustion X from combustion section  18  and delivers them downstream into duct  24 . A flow sleeve  32  is positioned radially between the outer housing  22  and the combustion liner  31 . A chamber  30  between the flow sleeve  32  and the outer housing  22  receives cooling air, such as from an upstream compressor (not shown). Holes  34  are formed through the flow sleeve  32 . Air passes from the chamber  30  through the holes  34 , and against the outer periphery of the combustion liner  31 . 
     As shown in  FIG. 2 , flow sleeve  32  and holes  34  may be supplemented at a downstream row of holes  35  by a tab ring  36 . Tab ring  36  has a cylindrical base  38 , and a plurality of tabs  40 . Further, the base  38  includes holes  37  to be aligned with the last row of holes  35 . As can be appreciated from  FIG. 2 , the tabs  40  do not extend over more than 180° defined about an axis extending through the holes  35 . That is, tabs  40  are only on the downstream side of the holes  35 . More specifically, as can be appreciated, the tabs  40  extend across less than 90°, and are generally formed to be tangent to an outer periphery of the hole at an upstream side. As can be appreciated from  FIGS. 2 and 3 , the tab  36  ring as disclosed extends over an entire 360° range about a central axis Z of the flow sleeve  32 . In practice, the tab ring  36  may extend for less than 360°, but in embodiments, extends for at least 270° about the axis. Again, in the disclosed embodiment, the tab ring  36  does extend for 360° and is a complete ring. The tabs  40  and base  38  are formed as a single piece in a disclosed embodiment. 
     As can be appreciated from  FIG. 3 , tabs  40  extend radially inwardly from the base  38 . As can be appreciated from  FIG. 3 , there are a plurality of circumferentially spaced tabs  40 , intermediate spaces  141  circumferentially intermediate the plurality of tabs  40 . 
       FIG. 4  shows the tab  40  extending inwardly from base  38 , and positioned inwardly of the flow sleeve  32 . 
     As can be appreciated from  FIG. 5 , the tabs  40  being aligned with the outer row of holes  35  shields cooling air from downstream cross-flow. Instead, cooling air from the holes  35  flows to an outer periphery of the combustion liner  31 . Further, since the tabs  40  are only on a downstream side of the holes  35 , and the base  38  does not extend as far radially inwardly as does the tab  40 , the air is urged to flow back upstream, through the space  39  provided by the base  38 . There will be a greater resistance to downstream flow due to the tab  40 . 
     As can be appreciated, the tab ring  36  can be said to have an upstream side and a downstream side, and tabs  40  are at the downstream side. Notably, this description allows for a portion of the base to extend on a downstream side of the tabs  40 . That is, the tabs  40  need not be at an extreme edge of the ring  36 , and can still be said to be at the downstream side. 
     Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.