Patent Publication Number: US-10787927-B2

Title: Gas turbine engine having a flow-conducting assembly formed of nozzles to direct a cooling medium onto a surface

Description:
FIELD OF THE INVENTION 
     The present invention relates to the cooling of a flow-connecting assembly of a turbomachine. 
     BACKGROUND OF THE INVENTION 
     Turbomachines, such as for example gas turbines, turbines or compressors, comprise flow-conducting assemblies which on a first side serve for the flow conduction of a first medium, which has a first temperature. 
     In particular in the case of turbines and in the case of gas turbines in the region of a turbine or of a combustion chamber of the gas turbine, the first medium, which is conducted on the first side of the flow-conducting assembly, has a very high temperature that makes it necessary to cool the flow-conducting assembly. Here it is already known from the prior art to cool the flow-conducting assembly on a second side using a second medium, which has a temperature that is lower than the first temperature. 
     Accordingly, US2010/0126174 discloses a gas turbine with a combustion chamber, wherein a wall of the combustion chamber inside on a first side serves for the flow conduction of the fuel flow. On a second side, the wall of the combustion chamber is cooled via an impingement cooling, wherein for this purpose spaced from the wall of the combustion chamber to be cooled, an impingement grille extends, which comprises openings. By way of the openings of the impingement grille, the second medium is conductable or guidable onto the second side of the flow-conducting assembly, namely the wall of the combustion chamber, in order to cool the same. 
     From US2010/0126174 it is evident that between the second side of the flow-conducting assembly to be cooled and the impingement grille a gap is formed whose width is defined by the distance between the second side of the flow-conducting assembly to be cooled and the impingement grille. The second medium, which serves for the cooling, flows through the openings of the impingement grille namely in a flow direction that extends approximately perpendicularly to the impingement grille and to the assembly to be cooled. By way of the gap, a discharge flow of the second medium is discharged out of the gap, which extends approximately perpendicularly to the flow of the second medium through the openings of the impingement grille. This discharge flow of the second medium out of the gap can negatively affect the flow of the second medium extending through the openings of the impingement grille, which is intended to strike the assembly to be cooled in the region of the second side of the assembly to be cooled. The effectiveness of the impingement cooling can be reduced by this. This is a disadvantage. 
     Starting out from this, an object of the present invention is the creation of a new type of turbomachine with improved impingement cooling. 
     SUMMARY OF THE INVENTION 
     According to the present invention, flow-conducting elements for the second medium are formed in the region of at least some of the openings which, emanating from the impingement grille, extend in the direction of the second side of the flow-conducting assembly to be cooled. 
     The conducting elements for the second medium ensure that the flow of the second medium conducted via the openings of the impingement grille is directed in a defined manner onto the second side of the assembly of the turbomachine to be cooled. By way of this, the impingement cooling can be improved. The risk that a discharge flow of the second medium out of the gap between the assembly to be cooled and the impingement grille negatively affects the flow of the second medium conducted via the openings can thus be effectively reduced. 
     Preferentially, between the second side of the flow-conducting assembly and the impingement grille a gap is formed whose width is defined by the distance between the second side of the flow-conducting assembly and the impingement grille. The flow-conducting elements for the second medium, emanating from the impingement grille, extend into the gap by as far as maximally 80% of the width of the gap and preferentially minimally 40% of the width of the gap. In particular, the flow-conducting elements for the second medium, emanating from the impingement grille, extend into the gap by as far as maximally 70% and preferentially minimally 50% of the width of the gap. Such flow-conducting elements allow a particularly effective impingement cooling of the assembly of the turbomachine to be cooled. 
     Preferentially, the respective flow-conducting element for the second medium covers the second medium in the region of the respective flow-conducting element before the discharge flow of the second medium out of the gap. This leads to a particularly effective cooling of the assembly of the turbomachine to be cooled by the impingement cooling. 
     Preferentially, the respective flow-conducting element is formed at least as a nozzle. By way of a nozzle, the flow velocity of the second medium can be increased in particular in order to render the cooling of the assembly to be cooled even more effective with the help of the impingement cooling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are explained in more detail by way of the drawings in which: 
         FIG. 1  shows a detail of a turbomachine in the region of a flow-conducting assembly and of an impingement grille; 
         FIG. 2  shows a detail of the turbomachine in the region of a flow-conducting element; 
         FIG. 3  shows a further detail of the turbomachine in the region of an alternative flow-conducting element; 
         FIG. 4  shows a further alternative flow-conducting element; 
         FIG. 5  shows a further alternative flow-conducting element; and 
         FIG. 6  shows a further alternative flow-conducting element. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
     The present invention relates to a turbomachine, such as for example a turbine, a compressor or a gas turbine, which besides a combustion chamber comprises a turbine. A turbomachine comprises multiple flow-conducting assemblies. 
     In a gas turbine, the combustion chamber for example is a flow-conducting assembly which conducts a fuel flow on a first side of a wall of the combustion chamber. Further flow-conducting assemblies of a turbomachine, such as for example a gas turbine, can be so-called cover segments, which radially outside follow moving blades of a turbine stage, for example of a high-pressure turbine stage and on a first side serve for the flow conduction of the medium to be expanded in the turbine. 
     Flow-conducting assemblies of a turbomachine are exposed to high temperatures in particular when the first medium to be conducted on the first side of the flow-conducting assembly has a high temperature as is the case in the region of a combustion chamber of a gas turbine or of a high-pressure turbine stage. 
     It is therefore known, in principle, to cool these flow-conducting assemblies on a second side located opposite the first side with a second medium, which has a second temperature that is lower than the first temperature. This cooling with the help of the second medium can be carried out via an impingement cooling. 
     The present invention relates to such details with the help of which the impingement cooling on a flow-conducting assembly of a turbomachine to be cooled can be improved. 
       FIGS. 1 to 3  each show extracts of a turbomachine according to the invention in the region of a flow-conducting assembly  10  to be cooled as well as in the region of an impingement grille  11 . The flow-conducting assembly  10  comprises a first side  12 , which serves for the flow conduction of a first medium, wherein this flow-conducting assembly  10  for example can be the wall of a combustion chamber or a cover segment of moving blades of a high-pressure turbine stage. 
     On a second side  13  located opposite, the flow-conducting assembly  10  is coolable with the help of a second medium which has a second temperature that is lower than the first temperature. This second medium is conducted or directed via the impingement grille  11  in the direction of the second side  13  of the flow-conducting assembly  10  to be cooled. 
     The impingement grille  11  comprises openings  14 , wherein the second medium flows via the openings  14  of the impingement grille in the direction of the second side  13  of the assembly  10  to be cooled. Between the second side  13  of the flow-conducting  10  of the turbomachine to be cooled and the impingement grille  11  comprising the openings  14 , a gap  15  is formed. The width X of the gap  15  is defined by the distance between the second side  13  of the flow-conducting assembly  10  and the impingement grille  11 . 
     In  FIGS. 2 and 3 , the flow of the second medium  14  of the impingement grille  11  in the direction of the second side  13  of the flow-conducting assembly  10  to be cooled is visualised with arrows  16 . Arrows  17  visualise a discharge flow of the second medium out of the gap  15 . 
     In terms of the present invention, a flow-conducting element  18 ,  19  for the second medium is formed in the region of at least one of the openings  14  of the impingement grille  11 , preferentially in the region of each of the openings  14  of the impingement grille  11 . Emanating from the impingement grille  11 , each flow-conducting element  18  or  19  extends in the direction of the second side  13  of the flow-conducting assembly  10  to be cooled into the gap  15 , wherein the respective flow-conducting element  18 ,  19  preferentially terminates spaced from the second side  13  of the flow-conducting assembly  10 . 
     The respective flow-conducting element  18 ,  19  defines, as it were, a flow-conducting passage  23  which continues the respective flow-conducting opening  14  of the impingement grille  11  in the direction of the second side  13  of the flow-conducting assembly  10  to be cooled. Each flow-conducting element  18 ,  19  is dimensioned in its length in particular in such a manner that the flow-conducting element  18 ,  19 , emanating from the impingement grille  11 , extends by as far as maximally 80% of the width X of the gap  15  into the gap  15 , particularly preferably by as far as maximally 70% of the width X of the gap  15 . The minimal length of the flow-conducting elements  18 ,  19  preferentially amounts to 40% of the width X of the gap  15 , particularly preferably at least 50% of the width X of the gap  15 . 
     As is evident from  FIGS. 1 to 3 , the flow-conducting elements  18 ,  19  are formed in such a manner that the flow-conducting elements  18 ,  19  for the second medium at least partly cover the flow of the second medium extending through the openings  14  in the region of the respective flow-conducting elements  18 ,  19  before the discharge flow  17  of the second medium out of the gap  15 . Here, the flow-conducting elements  18 ,  19  can be contoured differently, the flow-conducting elements can also have different lengths, i.e. emanating from the impingement grille  11 , project into the gap  15  by a different distance. 
     The flow-conducting element  18  of  FIGS. 1, 2  is contoured circular or pipe-like in the cross section. 
     The flow-conducting element  19  of  FIGS. 1, 3  is contoured semi-circular or half pipe-like in the cross section. 
     The flow-conducting elements can also be embodied part circular or elliptical or semi-elliptical or part-elliptical or spar-like or the like. 
       FIGS. 4, 5 and 6  show further versions of possible flow-conducting elements  20 ,  21  and  22 . The flow-conducting element  22  of  FIG. 6  has a first section  22   a  that is contoured circular or pipe-like in the cross section and a second section  22   b  which is contoured semi-circular or half pipe-like in the cross section. The flow-conducting elements  18 ,  19  and  22  of  FIGS. 1, 2, 3 and 6  each extend perpendicularly to the impingement grille  11 . The flow-conducting elements  20 ,  21  of  FIGS. 4 and 5  each extend inclined towards the impingement grille  11  relative to a perpendicular. 
     While in  FIG. 4  the opening  14  in the impingement grille  11  is inclined and merges without any step into a flow-conducting passage  23  defined by the flow-conducting element  20 , a step or a deflection is formed in  FIG. 5  between the opening  14  of the impingement grille  11  and the flow-conducting passage  23  of the flow-conducting element  21 . 
     Regarding other details of the flow-conducting elements  20 ,  21  and  22 , preference can be made to the explanations regarding the flow-conducting elements  18 ,  19 . 
     The respective flow-conducting element  18 ,  19 ,  20 ,  21 ,  22  can be formed as nozzle or receive a nozzle at least in sections. By way of the constriction of the flow-conducting element  18 ,  19 ,  20 ,  21 ,  22  to form a nozzle, the flow velocity of the flow  16  of the second medium conducted via the opening  14  of the impingement grille  11  can be increased as a result of which the impingement cooling can be rendered even more effectively. The respective flow-conducting element  18 ,  19 ,  20 ,  21 ,  22  is preferentially an integral part of the impingement grille  11  and can be constructed on the impingement grille  11  by way of an additive or generative production method. The respective flow-conducting element  18 ,  19 ,  20 ,  21 ,  22  however can also be embodied as a separate assembly and connected to the impingement grille  11 . 
     The openings  14  of the impingement grille  11  are typically contoured circular. The invention is preferentially applied where the width X of the gap  15  between the assembly  10  to be cooled and the impingement grille  11  is greater than twice the diameter of the openings  14  of the impingement grille  11 . In this application case, the invention can be particularly advantageously utilized. However, the invention is not restricted to this preferred application case. 
     Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.