Patent Publication Number: US-2019178262-A1

Title: Flow Machine And Method For The Production Thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. national stage of application No. PCT/EP2017/051976, filed on Jan. 31, 2017. Priority is claimed on German Application No. DE102016213296.2, filed Jul. 20, 2016, the content of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a turbomachine, in particular to a radial turbomachine, and to a method for producing the same. 
     2. Description of the Prior Art 
     From U.S. Pat. No. 6,669,436 B2 a turbomachine, namely a radial compressor, having a rotor comprising moving blades and a stator comprising guide blades is known. Seen in the flow direction of the medium to be compressed, the guide blades of the stator are designed as guide blades of a diffuser arranged downstream of the moving blades of the rotor. Accordingly, the guide blades are positioned in the region of a flow passage, which leads away from the moving blades of the rotor. From U.S. Pat. No. 6,669,436 B2 it is known, furthermore, to provide a sound-damping element in the region of the diffuser, namely in the region of the guide blades of the diffuser. Here, this sound-damping element is an integral part of a diffuser ring designed as a plate-like ring with multiple apertures, wherein the apertures lead to hollow spaces. The sound-damping element known from U.S. Pat. No. 6,669,436 B2, which is an integral part of a diffuser ring, acts as a resonator which comprises hollow spaces which, via apertures, are in connection with the flow passage in the region of the diffuser. The damping effect of such a sound-damping element is limited. 
     SUMMARY OF THE INVENTION 
     Starting out from this, one aspect of the present invention is a new type of turbomachine and a method for producing the same. 
     According to one aspect of the invention, the stator, in the region of at least one flow passage, comprises at least one foam-like porous sound-damping element. Such a sound-damping element has good sound-damping characteristics while the same, furthermore, can be produced simply and cost-effectively. 
     According to an advantageous further development, the respective foam-like sound-damping element is designed as a metal foam element, which is preferentially produced by way of a generative manufacturing method and individually formed as sintered metal foam-like element. A metal foam element as sound-damping element produced by way of a generative manufacturing method is particularly preferred. 
     Preferentially, the porosity of the respective foam-like sound-damping element is not equally distributed but locally different in terms of the number of pores and/or pore depth. The variation of the porosity is not solely dependent on the pore size but also on the material density with constant pore size. The variation of the pore size and pore shape also influences the porosity. By way of the different distribution of the porosity of the respective sound-damping element, the sound-damping characteristics and strength properties can be optimally adjusted. 
     According to an advantageous further development, the respective foam-like sound-damping element is an integral part of a diffuser comprising guide blades. Preferentially, the guide blades have a flow leading edge, a flow trailing edge and flow control surfaces extending between these edges, wherein in a middle region between the flow leading edge and the flow trailing edge a larger number of pores is and/or are formed than in the regions adjoining the flow leading edge and the flow trailing edge, and/or wherein in a middle region between the flow control surfaces of adjacent guide blades a larger number of pores and/or deeper pores is and/or are formed than in the regions adjoining the respective flow control surface. By way of this, the sound damping characteristics can be optimally adjusted in the region of the diffuser. 
     According to an advantageous further development of the invention, walls, delimiting the respective flow passage and/or guide blades positioned in the respective flow passage are embodied as flow-like, porous sound-damping element at least in sections. This allows an optimal adjustment of sound-damping characteristics in the region of a stator-side flow passage of a turbomachine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred further developments of the invention are obtained from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail by way of the drawing without being restricted to this. 
       There it shows: 
         FIG. 1  is an axial section through a turbomachine designed as radial compressor; 
         FIG. 2  is a view in the direction II of  FIG. 1  of a diffuser of the radial compressor of  FIG. 1 ; 
         FIG. 3  is a view in the direction II of  FIG. 1  of an alternative diffuser of the radial compressor of  FIG. 1 ; 
         FIG. 4  is a view in the direction II of  FIG. 1  of a further alternative diffuser of the radial compressor of  FIG. 1 ; and 
         FIG. 5  is an axial section through a further turbomachine designed as radial compressor. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
     The invention relates to a turbomachine, in particular to a radial turbomachine. The invention, furthermore, relates to a method for producing such a turbomachine. 
       FIGS. 1 and 2  show different views of a turbomachine  10  designed as radial compressor. 
     The turbomachine  10  of  FIGS. 1 and 2  formed as radial compressor comprises a rotor  11  with moving blades  12 . Furthermore, the turbomachine  10  designed as radial compressor comprises a stator  13 , wherein the stator  13  on the one hand delimits a flow passage  14  leading to the moving blades  12  of the rotor  11  extending in the axial direction on the other hand a flow passage  15  leading away from the moving blades  12  of the rotor  11  and extending in the radial direction, at least in sections. 
     A diffuser  16  comprising guide blades  17  is part of the stator  13 . Seen in the flow direction of the medium to be compressed, the guide blades  17  of the diffuser  16  are positioned downstream of the moving blades  12  of the rotor  11  in the flow passage  15  extending in the radial direction. A spiral-shaped outflow housing  18  of the stator  13  follows downstream of the diffuser  16 . The flow direction of the medium to be compressed is visualised by arrows  19  in  FIG. 1 . 
       FIG. 2  shows a view II of the diffuser  16 , namely of the guide blades  17  of the diffuser  16  and of a wall  24  of the same. Each of the guide blades  17  comprises a flow leading edge  20 , a flow trailing edge  21  and flow control surfaces  22  extending between the respective flow leading edge  20  and the flow trailing edge  21 . In the case of the turbomachine according to the invention, the stator  13  comprises a foam-like, porous sound-damping element  23  in the region of at least one flow passage  14  and/or  15 . 
     The respective foam-like, porous sound-damping element  23  can be formed as a metal foam element, in particular as a sintered metal-like element, or as a plastic foam element. In the case of a metal foam element, the same is preferentially produced by way of a generative manufacturing method. 
     In the exemplary embodiment of  FIGS. 1 and 2 , in which the stator  13 , in the region of the diffuser  16 , comprises the or each foam-like, porous sound-damping element  23  it is provided that walls  24  of the stator  13 , which in sections delimit the flow passage  15  leading away from the guide blades  12  of the rotor  11  at least in sections are embodied as foam-like, porous sound-damping element  23  at least in sections, namely preferentially on both axial sides or only on one axial side of the flow passage  15  of the stator  13  extending in the radial direction and leading away from the moving blades  12  of the rotor  11  in the region of the diffuser  16 . This allows a particularly effective sound-damping. Pressure shocks emanating from the rotor  11  and acting on the diffuser  16  can be directly dampened at the source. 
     In the exemplary embodiment shown in  FIGS. 1 and 2 , the porosity of the respective foam-like sound-damping element is equally distributed, i.e. the foam-like sound-damping element  23  has an equal distribution in term of number, depths, and size of the pores. 
     Compared with this,  FIGS. 3 and 4  show versions of the invention in the case of which the respective foam-like sound-damping element  23  in terms of number of pores and pore depth does not have an equally distributed porosity but rather a locally distinct porosity. Accordingly, the walls  24  extending in the radial direction in  FIGS. 3 and 4 , which in sections delimit the flow passage  15  extending in the radial direction in the region of the diffuser  16 , are embodied in sections as foam-like porous sound-damping element  23 . 
     In  FIG. 3 , a larger number of pores and a greater depth of the pores is provided or formed in a middle region between the flow leading edge  20  and the flow trailing edge  21  than in regions that are directly adjoining the flow leading edge  20  and the flow trailing edge  21 . 
     In  FIG. 4 , the porosity of the walls  24  of the rotor  13  delimiting the flow passage  15  extending in the radial direction is additionally locally distinct in the region of the diffuser  16  in such a manner that in a middle region between the flow control surfaces  22  of adjacent guide blades  17  of the diffuser  16  a larger number of pores and deeper pores is or are formed than directly adjacent to the respective flow-controlling surface  23  of the respective guide blade  17 . 
       FIG. 5  shows the walls  24  of the stator  13  delimiting the flow passage  15  extending in the radial direction in the region of the diffuser  16  have a locally distinct porosity seen over their axial thickness. Accordingly it is provided in  FIG. 5  that in an axially middle region of these walls  24 , larger pores are formed than directly adjacent to the flow passage  15 . 
     Although it is preferred that walls  24  delimiting the respective flow passage  14 ,  15  are at least in sections embodied as foam-like porous sound-damping elements  13 , it is alternatively or additionally also possible that guide blades  17  positioned in the respective flow passage  14 ,  15  are embodied as foam-like porous sound-damping elements  13  at least in sections. 
     In the shown exemplary embodiments, the stator  13  comprises at least one foam-like porous sound-damping element  23  in the region of the flow passage  15  leading away from the moving blades  12  of the rotor  11 . 
     Alternatively or additionally it is also possible that the stator  13 , in the region of the flow passage  14  leading towards the moving blades  12  of the rotor  11 , comprises at least one such foam-like porous sound-damping element  23 . 
     In the shown exemplary embodiments, the turbomachine  10  is embodied as radial compressor. It is also possible that the invention is employed with a radial turbomachine designed as radial turbine. In the case of a radial turbine, a flow passage leading towards the moving blades of the rotor extends in the radial direction and a flow passage leading away from the moving blades of the rotor, in the axial direction. 
     However, turbomachines combining a radial and an axial design are also possible as alternative. 
     The respective foam-like porous sound-damping element  23  produces a viscous sound-damping. Thus, sound can be more effectively dampened than with conventional resonator-type sound dampers. In particular, high-frequency vibration excitations of the rotor and of assemblies located downstream of the rotor can also be reduced. In addition, a reduced loss of pressure in the flow than with resonator-type sound dampers is incurred. 
     The invention also relates to a method for producing a turbomachine, while the rotor  11  and the stator  13  are provided for this purpose. 
     The rotor  11  can be a precision casting, chip-machined forging or chip-machined integrally produced component. 
     Furthermore, the stator  13  can be a precision casting at least in sections. 
     In the region of the or each foam-like, porous sound-damping element  23 , the stator  13  is produced by way of a generative manufacturing method at least in sections. 
     In particular when the respective foam-like sound-damping element  23  is formed as a metal foam element, in particular an additive manufacturing method such as for example (selective) laser beam melting or electron beam welding can be utilised in particular. In this case, the metal foam is a sintered metal-like generated metal foam. 
     In particular when the diffuser  16  comprises at least one foam-like porous sound-damping element  23 , a so-called diffuser ring of the diffuser  16 , which at least provides a section of one of the walls  24  of the stator-side diffuser  16  and integrally also the guide blades  17  of the same is preferentially produced by way of a generative manufacturing method. In this case, the respective sound-damping element  23  is an integral part of the diffuser ring and thus of the diffuser  16 . The diffuser ring provides the guide blades  17  of the diffuser  16  and at least in sections one of the walls  24 , which delimit the flow passage  15  extending in the radial direction. 
     The specific section of the stator  13  comprising a foam-like sound-damping element  23 , which is produced via a generative manufacturing method, is connected to an adjoining section of the stator  13  that is preferentially produced by precision casting and for this purpose inserted into a corresponding recess in the section of the stator  13  produced by precision casting. 
     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.