Abstract:
A circular array of generally L-shaped flow paths ( 28 ) in an injector housing ( 32, 34 ) encircling a gas turbine rotor ( 24 ), each of the flow paths having an inflow leg ( 28 A ) oriented generally radially with respect to the rotor axis ( 58 ), and an outflow leg ( 28 B) oriented partly axially and partly tangentially. An adjustment plate ( 50 ) may be attached to the injector ( 20 ) at an adjustable position ( 52 ) to partially block an inflow passage ( 38 ) of the injector in order to adjust the flow of cooling air ( 27 ) through the respective flow path.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to non-rotating nozzles or vanes for injecting cooling air into a channel in a gas turbine rotor, and directing the air from the injector outlets so as to match rotation of the rotor cooling channel inlet. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cooling air for a gas turbine engine may be drawn from the turbine compressor section in piping that bypasses the combustors. Tangential On-Board Injector (TOBI) devices inject the cooling air into channels in the rotor of the turbine section. It may flow through the turbine shaft, then outward through passages in the turbine disks and blades, where it may exit into the working gas. Various injector designs have been used to direct cooling air from non-rotating injector outlets into rotating cooling channel inlets in the turbine rotor. Some designs use holes or bores as nozzles, and others use airfoil type nozzles, or vanes, that define cooling flow paths between them. However, according to U.S. Pat. No. 6,379,117 issued to Ichiryu on Apr. 30, 2000, it is extremely difficult to incline airfoil type nozzles to the tangential direction and to the axial direction simultaneously. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    The invention is explained in following description in view of the drawings that show: 
           [0004]      FIG. 1  is a sectional view of an injector according to aspects of the invention taken along a plane of the gas turbine rotor axis. 
           [0005]      FIG. 2  is a partial perspective view of the injector housing and vanes of  FIG. 1 . 
           [0006]      FIG. 3  is a top view of a planar generally L-shaped vane similar to the ones used in  FIGS. 1 and 2 . 
           [0007]      FIG. 4  is a top view of a generally L-shaped vane with a flat inflow leg and a curved outflow leg. 
           [0008]      FIG. 5  is a sectional view of an aspect of the invention using vanes in an annular outflow area of an annular flow passage. 
           [0009]      FIG. 6  is a partial perspective view of the injector housing and vanes of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    The inventor recognized that a tangential on-board injector with a circular array of generally L-shaped flow paths could provide an axial-tangential outflow for efficiency, and could use airfoil type nozzles, or vanes, thus overcoming the difficulty mentioned by Ichiryu. This would maximize fluid dynamic efficiency, and minimize manufacturing cost. The terms “axial” and “radial” herein relate to a turbine rotor axis and radii thereof. The term “tangential” herein means tangent to a circle of rotation of a point on the turbine rotor. The term “generally L-shaped flow path” herein means a flow path with two mutually generally orthogonal portions. The term “L-shaped vane” herein means an airfoil with a generally “L-shaped” profile as viewed facing the pressure or suction surface of the airfoil. The corner of the “L” shape may be highly curved. The inventor also recognized that a simple adjustment mechanism could be provided on the injector to optimize the cooling flow rate for each installation without custom machining of the injector. 
         [0011]      FIG. 1  is a sectional view of a cooling air injector  20  according to aspects of the invention. A hot working gas  22  from combustors drives a gas turbine rotor  24 . Cooling passages or pipes  26  provide fluid for the injector inflow  27 . This fluid may be air drawn from the turbine main compressor, bypassing the combustors as known in the art, and/or it may be a gas obtained from or mixed with other engine sources as known in the art. The injector  20  may have an annular flow passage  36  formed between two annular walls  32 ,  34 . An injector mounting portion or flange  35  may provide for attachment bolts. Generally L-shaped flow paths  28  are defined by generally L-shaped sectional profiles of the annular flow passage  36  between vanes  30 , as seen for example in  FIG. 1 . Each flow path  28  may have a generally radial inflow leg  28 A and an axial-tangential outflow leg  28 B. The annular flow passage  36  may have a generally radially oriented annular inflow passage  38  and a generally axially oriented annular outflow passage  40 . Generally L-shaped vanes  30  may form a circular array of vanes  30  within the annular flow passage  36 . The annular walls  32  and  34  span and interconnect the vanes  30 . As shown in  FIGS. 2 and 3 , the vanes  30  and flow paths  28  may be angled  42  as if pivoted about a radius of the rotor axis. The corner  44  of the “L” shaped sectional profile of flow passage  36  causes a redirection of the cooling flow path  28  from radial to axial. The angle  42  of the vanes  30  provides a partial redirection to tangential. The cooling air outflow  29  is thus partly axial and partly tangential. The injector outflow rate and tangential angle  42  may be engineered such that the tangential component of the outflow  29  approximately matches the rotation speed of cooling channel inlets  46  in the rotor  24 . Thus, cooling air  29  entering the rotor cooling channels  48  will not cause drag on the rotor, but will merge with the rotating cooling channel inlets  46  and move into the cooling channels  48 . The injector outflow  29  initially forms a generally helical flow pattern until it is otherwise directed or released from the cooling channels  48 . 
         [0012]    As also shown in  FIG. 1  is a flow adjustment plate  50  that may be provided to variably partially cover the inflow passage  38 . For example, the injector may be installed with the adjustment plate  50  positioned  52  to provide 10-20% inflow blockage. After running the gas turbine, the cooling air supply pressure and other parameters can be measured, and appropriate positional adjustment  52  of the flow adjustment plate  50  can be made to meet cooling specifications. The adjustment plate  50  may be formed as two or more arcuate segments with axially oriented slots  54  fixed by bolts  56 . 
         [0013]      FIG. 2  illustrates in partial perspective an embodiment of the invention with flat, generally L-shaped vanes  30 , each with a radial inflow leg  30 A and an axial-tangential outflow leg  30 B. A top view of such a vane  30  is illustrated in  FIG. 3 , which shows an angle  42  of the vane  30  with respect to the rotor axis  58  that provides a tangential component to the outflow  29  in the direction of rotor rotation.  FIG. 4  illustrates an alternate vane  30 ′ with a flat inflow leg  30 A′ and a curved outflow leg  30 B′. Either or both legs of a generally L-shaped vane may be angled and/or curved toward the direction of rotor rotation. 
         [0014]      FIGS. 5 and 6  illustrate an injector embodiment  21  with axial-tangential vanes  31  extending in the outflow passage  40  only of the injector flow passage  36 . The annular inflow passage in this embodiment is an annular plenum  38 ′ incorporating all of the radial inflow legs  28 A but containing no vane, with the annular plenum directing the cooling air into the spaces between the vanes  31 . Generally L-shaped flow paths  28  pass between the vanes  31  as seen in  FIG. 5 . The vanes  31  are oriented partly axially and partly tangentially. The vanes may be planar as shown, or curved. 
         [0015]    While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.