Abstract:
The English-language Abstract from the international application is to be retained and is therefore not duplicated in the specification.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Phase application submitted under 35 U.S.C. §371 of Patent Cooperation Treaty application serial no. PCT/DE2011/000040, filed Jan. 15, 2011, and entitled HOUSING SYSTEM FOR AN AXIAL TURBOMACHINE, which application claims priority to German patent application serial no. 10 2010 005 153.5, filed Jan. 21, 2010, and entitled GEHÄUSESYSTEM FÜR EINE AXIALSTRÖMUNGSMASCHINE. 
         [0002]    Patent Cooperation Treaty application serial no. PCT/DE2011/000040, published as WO 2011/088819, and German patent application serial no. 10 2010 005 153.5, are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0003]    The invention relates to a housing system for an axial turbomachine as well as to an axial turbomachine with such a housing system. 
       BACKGROUND 
       [0004]    Housing systems for axial turbomachines such as, for example, airplane turbines comprise a housing in which vanes are customarily arranged in a crown shape. These vanes, that form a so-called “vane cluster”, should be sealed as pressure-tight as possible against the housing in order to avoid unnecessary flow losses during the operation of the associated axial turbomachine. However, large thermal gradients with correspondingly high loads in the area of the rear closing wall occur in the case of vane clusters with a large circumferential extension and a high closing wall. Therefore, after a certain size of the housing and/or of the vanes a continuous closing wall is no longer possible, so that the vanes are fastened by individual fastening elements on the housing. Such a housing system can be gathered, for example, from U.S. Pat. No. 4,194,869. 
         [0005]    However, comparatively many slots are produced between the fastening elements and the housing by this type of fasting, which slots must be sealed by a sealing element in order to reduce the leakage flows occurring during operation. For example, sealing platelets (so-called “leaf seals”) or sealing rings that surround the outer vane feet are known from the prior art. 
         [0006]    However, these known sealing elements are considered to have the disadvantageous circumstance that they are relatively expensive and complicated to mount and that their sealing action frequently weakens during the operation of the axial turbomachine. This leads to a reduced effectiveness and to a correspondingly elevated fuel requirement. 
       SUMMARY AND DESCRIPTION 
       [0007]    The present invention has the task of creating a housing system of the initially cited type that ensures a uniformly high sealing action during the operation of an associated axial turbomachine. 
         [0008]    The invention solves the task with the housing system with the features as described and claimed as well as within axial turbomachine as described and claimed with such a housing system. Advantageous embodiments with purposeful further developments of the invention are indicated in the subclaims, whereby advantageous embodiments of the housing system are to be considered as advantageous embodiments of the axial turbomachine and vice versa. 
         [0009]    A housing system in accordance with the invention for an axial turbomachine, in particular for an airplane turbine, comprises a housing, at least one vane that is fastened on the housing by at least one fastening element, a sealing element for reducing a leakage flow between the fastening element and the housing, whereby the sealing element is arranged between a fastening element wall located downstream relative to a direction of flow of the axial turbomachine and between a wall of the housing, and comprises a pressure means by means of which the sealing element can be loaded with an axial force at least during the operation of the axial turbomachine and can be pressed against the wall of the housing. It is ensured in this manner that the sealing element is pressed against the housing wall acting as a sealing contact surface with the aid of the pressure means, as result of which a very high and uniform sealing action is ensured during the operation of the axial turbomachine. In addition, the housing system can be economically produced and readily mounted so that corresponding advantages of cost result in the production as well as in the maintenance, repair and overhauling. 
         [0010]    An advantageous embodiment of the invention provides that the sealing element is slotted and/or annular and/or multipartite and/or elastically deformable. A slotted sealing element advantageously facilitates the assembly on account of its increased mobility. Since the sealing element is annular, the improved sealing action can be ensured over the entire circumference of the housing. It can be provided that the sealing element is in one part or multipartite, for example, in the form of several annular segments, which creates an elevated constructive freedom. Since the sealing element can be elastically deformed, the sealing element can undulate, so that a tolerance compensation is readily ensured in the circumferential direction of the housing and therefore a continuous contact of the sealing element on the wall is ensured. 
         [0011]    Further advantages result if the fastening element has a hook-shaped area that is arranged in an associated receptacle of the housing. This makes possible a simple mounting and dismounting of the at least one vane on the housing. 
         [0012]    In a further embodiment of the invention it proved to be advantageous if the fastening element is arranged on a radially outer blade foot of the vane since in this manner the aerodynamic properties of the at least one vane are not adversely affected. In addition, the fastening element in axial turbomachines constructed as airplane turbines is arranged as a consequence on a side facing away from the hot gas and is exposed to lesser thermal loads during operation. 
         [0013]    In a further advantageous embodiment of the invention the sealing element comprises at least one through opening, in particular a metering bore, by means of which a flow of cool air can be adjusted between a space of the housing system that is arranged upstream from the fastening element and between a space of the housing element arranged downstream from the fastening element. On account of the high tightness a flow of cool air necessary for the operation of the particular associated axial turbomachine can be very precisely adjusted via the through opening. This can advantageously save cooling air and improve the effectiveness of the axial turbomachine. 
         [0014]    Further advantages result in that the pressure means is constructed as a pressure edge on the fastening element. As a result of such a design of the pressure means the sealing element is pressed during the operation of the associated axial turbomachine against the housing wall via the forces of the operating fluid acting on the at least one vane with an axial force applied via the fastening element by the pressure edge, which achieves a contact that is safe in operation and an especially high sealing action in a constructively simple manner. 
         [0015]    In another advantageous embodiment of the invention a groove is provided in which a radially inner end area of the sealing element is arranged. This makes possible an arrangement of the sealing element that is especially secure in operation and against falling out. Furthermore, as a consequence, a wall of the groove can also act as a sealing contact surface against which the sealing element is pressed with the aid of the pressure means at least during the operation of the associated fastening element. This further improves the sealing action. 
         [0016]    It proved to be advantageous if the groove is designed to be oblique. In this manner the sealing element in the oblique groove is supported against undesired tilting, which further improves the operational security of the housing system. 
         [0017]    In a further embodiment the groove is arranged offset relative to the pressure means. In other words, the groove is not in alignment with the pressure means. In this manner an especially reliable contact of the sealing element on the housing wall and on a wall of the groove is ensured, which results in an especially high sealing action under all operating conditions of the axial turbomachine. 
         [0018]    Another advantageous embodiment of the invention provides that the groove is formed by corresponding recesses in the fastening element and in the vane. As a result, the groove can advantageously be constructed after the fastening of the fastening element and of the at least one vane on the housing—for example, by milling—in one method step. In this manner any offset between the recess of the fastening element and the corresponding recess of the vane is avoided. Alternatively, it can also be provided that the recesses are manufactured during the manufacture of the fastening element and/or of the vanes already—for example by separation and/or by master patterning. 
         [0019]    In another advantageous embodiment of the invention several vanes are provided that are arranged in the form of a vane crown on the housing. As a result the housing system makes possible a purposeful influencing of the flow in an associated axial turbomachine so that the operating fluid of the axial-machine can strike rotor blades arranged downstream from the vane crown at an optimal angle. This achieves, together with the improved sealing action, a significantly heightened effectiveness of the axial turbomachine. 
         [0020]    It turned out to be advantageous in a further embodiment if the vane crown comprises several vane elements, whereby each vane segment is fastened by at least two fastening elements on the housing. This makes possible a rapid, simple and stable fastening of the vanes on the housing of the housing system. 
         [0021]    Another aspect of the invention relates to an axial turbomachine, in particular an airplane turbine, that comprises a housing system in accordance with one of the previous exemplary embodiments. This ensures a high sealing action during the operation of the axial turbomachine, which results in a correspondingly improved effectiveness of the axial turbomachine. The further features and their advantages resulting from the above can be gathered from the previous descriptions. 
         [0022]    It furthermore turned out to be advantageous if at least one rotor blade is arranged upstream and/or downstream from the vane. This allows a constructively flexible adaptability of the axial turbomachine to different uses and construction forms. 
         [0023]    Another advantageous embodiment of the invention provides that the housing of the housing system comprises at least one seal, in particular an inlet seal and/or a honeycomb seal for reducing a leakage flow between the housing and a blade tip of the at least one rotor blade. The effectiveness of the axial turbomachine is additionally raised with the aid of such a seal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Further features of the invention result from the claims, the exemplary embodiment as well as from the drawings. The features and feature combinations cited in the previous specification as well as the features and feature combinations cited subsequently in the exemplary embodiment can be used not only in the particular indicated combination but also in other combinations or by themselves without leaving the scope of the invention. In the figures: 
           [0025]      FIG. 1  shows a schematic lateral cutaway portion of a housing system in accordance with the invention; 
           [0026]      FIG. 2  shows a schematic lateral sectional view, increased relative to the arrangement of the sealing element, of the detail II shown in  FIG. 1 ; 
           [0027]      FIG. 3  shows a schematic perspective view in a cutaway portion of the housing system shown in  FIG. 1 ; 
           [0028]      FIG. 4  shows a schematic perspective view in a cutaway portion of a vane crown shown in  FIG. 3 ; 
           [0029]      FIG. 5  shows a schematic front view in a cutaway portion of the vane crown shown in  FIG. 3  and  FIG. 4 ; and 
           [0030]      FIG. 6  shows a schematic perspective view of the detail VI shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows a schematic lateral cutaway portion of an exemplary embodiment of a housing system  10  in accordance with the invention for an axial turbomachine constructed as an airplane turbine (not shown).  FIG. 1  is explained in the following viewed together with  FIG. 2 . For its part,  FIG. 2  shows a schematic lateral sectional view of the detail II, whereby the arrangement of the sealing element is shown in an increased manner for a more detailed illustration. The housing system  10  comprises a multi-partite housing  12  and a plurality of vanes  14  of which several are combined on a common platform to vane segments  16  (see  FIG. 3 ). For their part, the individual vane segments  16  are arranged inside the housing  12  in the form of a vane crown  17  as a so-called “vane cluster”. The vanes  14  can be constructed basically fixed and/or adjustable. The vanes  14  and/or the vane segments  16  are fixed on the housing  12  by fastening elements  18  described in detail in the following. 
         [0032]    A rotor blade ring (not shown) comprising several rotor blades  15  is arranged inside the housing  12  of the housing system  10  in the present exemplary embodiment relative to a direction of flow I of the axial turbomachine downstream from the vanes  14 . In order to reduce a leakage flow between the housing  12  and the blade tips of the rotor blades  15 , the housing  12  of the housing system  10  comprises a seal  19  constructed in the present case as a known inlet seal. 
         [0033]    In order to reduce a leakage flow between the fastening elements  18  and the housing  12  a static sealing element  20  is provided that is arranged between a wall  22  of the fastening element  18 , which wall is located downstream relative to the direction of flow I of the axial turbomachine, and between a wall  24  of the housing  12 . The wall  24  of the housing  12  thus functions as an axial sealing contact surface rotating in the circumferential direction of the housing  12 . The sealing element  20  is slotted in the present exemplary embodiment and constructed in a multi-partite manner in the form of annular segments. Furthermore, the sealing element  20  can be elastically deformed, as a result of which it can deform in an undulating manner between adjacent fastening elements  18  and makes reliable contact (cf.  FIG. 6 ). To this end the sealing element  20  can be manufactured, for example, from a springy, elastic, temperature-stable and/or metallic material. Instead of the multi-partite construction in the form of annular segments shown, it can alternatively be provided that the sealing element  20  is constructed in one part—for example, annularly. The sealing element  20  is clamped in a manner explained in detail in the following during the operation of the airplane turbine by the gaseous forces occurring on the vanes  14  so that an especially high and operationally secure sealing effect is achieved in a simple and economical manner. 
         [0034]    As can be well recognized in particular in  FIG. 2 , the fastening element  18  has a hook- shaped area  26  arranged in an associated receptacle  28  of the housing  12 . This achieves a positive connection with a low installation height, whereby the shape of the receptacle  28  and the shape of the fastening element  18  are coordinated with one another. In addition, the vanes  14  can be readily mounted on the housing  12  and dismounted from this housing as a result. Each fastening element  18  is arranged on a radially outer blade foot  30  of the particular vane  14 . In addition to the support of the vanes  14 , another important function of the blade feet  30  consists in the sealing action relative to a rotor of the axial turbomachine in order to avoid a recirculation of the compressed air from a chamber  32   a  with a rather high pressure into a chamber  32   b  with a rather low pressure. Due to the high tightness the sealing element  20  has several through openings  34  distributed over the circumference and constructed as metering bores (cf.  FIG. 3 ) by means of which openings a flow of cooling air can be adjusted between the space  32   a  with a higher pressure located upstream from the fastening element  18  and between the space  32   b  of the housing system  10 , which space  32  is located downstream from the fastening element  18 . In this manner the necessary flow of cooling air can be very precisely adjusted so that cooling air is saved and the effectiveness of the airplane turbine is additionally improved. 
         [0035]    As can be recognized in particular in  FIG. 2  the fastening element  18  comprises a pressure means  36  constructed in the present instance as a pressure edge bordering the wall  22 . Furthermore, the fastening element  18  comprises an oblique groove  38  in which a radially inner end area  20   a  of the sealing element is arranged. The groove  38  is offset, viewed in the direction of flow I, relative to the pressure means  36  and is therefore not in alignment with the wall  22  of the fastening element  18 . The groove  38  is formed in the present exemplary embodiment by two corresponding recesses  38   a,    38   b.  The recess  38   a  is formed in the fastening element  18  and the recess  38   b  in the vane  14 , whereby the recess  38   b  functions together with the wall  24  of the housing  12  as a sealing contact surface. In other words, the groove  38  is constructed relative to the sealing element  20  in the area IIa with a “covering”, as a result of which the sealing element  20  is clamped between the fastening element  18 , the housing  12  and the recess  38   b  of the vane  14  and the pressure means  36  can exert an especially large axial pressure force on the sealing element  20 . Thus, the sealing element  20  is pressed by the axial force of the vanes  14  acting parallel to the direction of flow I via the pressure edge  36  against the wall  24  of the housing  12 , which wall serves as axial sealing contacts, and against the wall of the recess  38   b.  The support is conceived in such a manner with the cited covering that the sealing element  20  rests completely on the walls  24  and  38   b.  The groove  38  is tilted in such a manner in the present case for manufacturing reasons that the pressure edge  36  makes possible the subsequent manufacture of the groove  38  after the fixing of the fastening element  18  on the housing  12  by a milling or grinding procedure. 
         [0036]      FIG. 3  shows a schematic and cutout perspective view of the housing system  10  shown in  FIG. 1 , whereby the housing  12  is illustrated only in a transparent sectional view for reasons of clarity. In particular the annular, segmental sealing element  20  can be well recognized with the through openings  34 . It can furthermore be recognized that each ring segment  16  is connected by several fastening elements  18  to the housing  12 . 
         [0037]      FIG. 4  shows a schematic and cutout perspective view of the vane crown  17  shown in  FIG. 3  without the housing  12  for further clarification. In a corresponding manner,  FIG. 5  shows a schematic and cutout frontal view of the vane crown  17  shown in  FIG. 3  and  FIG. 4  in the direction of flow I. It is apparent here that the abutment areas of the individual vane segments  16  and of the annular segments of the sealing element  20  are offset relative to each other in the circumferential direction in order to ensure a high sealing action even under fluctuating temperature conditions. 
         [0038]      FIG. 6  shows a schematic perspective view of the detail VI shown in  FIG. 5 . In particular, the space  32   b  with a lower pressure as well as the abutment area between two vane segments  16  are recognizable. Furthermore, the arrow VIa characterizes an area between two adjacent fastening elements  18  in which the elastic sealing element  20  is deformed in an undulating manner in the circumferential direction so that it rests completely on the wall  24  and the wall of the recess  38   b.