Abstract:
A rotor for a double-flow turbomachine is provided, wherein the first flow and the second flow have several rows of rotor blades, wherein at least one row of rotor blades is different from the corresponding row of rotor blades of the other flow.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the US National Stage of International Application No. PCT/EP2012/072096 filed Nov. 8, 2012, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP12000481 filed Jan. 25, 2012. All of the applications are incorporated by reference herein in their entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The invention relates to a rotor for a two-channel turbomachine, in particular a steam turbine, wherein the rotor has a first rotor section for a first channel and a second rotor section for a second channel, wherein the first rotor section has a first rotor blade row, a second rotor blade row and further rotor blade rows as well as a final rotor blade row, wherein the second rotor section has a first, second and further rotor blade rows, as well as a final rotor blade row. 
       BACKGROUND OF INVENTION 
       [0003]    Turbomachines, such as steam turbines, comprise in general a rotor which is mounted such that it can rotate and a housing which is arranged about the rotor. There is a risk that certain torsional frequencies could lead to destruction of the rotor or of the rotor blades on the rotor. For this reason, the rotors for turbomachines are configured for a certain range of operational frequencies, in which no torsional frequencies arise, wherein it is known that the rotor blades which are arranged on the rotors have an effect on the torsional frequencies. 
       SUMMARY OF INVENTION 
       [0004]    It is an object of the invention to propose a rotor for a turbomachine which has a lower tendency to torsional frequencies. 
         [0005]    This object is achieved with a rotor for a two-channel turbomachine, in particular a steam turbine, wherein the rotor has a first rotor section for a first channel and a second rotor section for a second channel, wherein the first rotor section has a first rotor blade row, a second rotor blade row and further rotor blade rows as well as a final rotor blade row, wherein the second rotor section has a first, second and further rotor blade rows, as well as a final rotor blade row, wherein the configuration of the rotor blades of a rotor blade row of the first rotor section is of different design to the configuration of the rotor blades of a rotor blade row of the second rotor section, wherein the rotor blades of the corresponding rotor blade rows of the first rotor section and of the second rotor section are of substantially identical design. 
         [0006]    The invention proceeds from the idea that, in the case of rotors of two-channel design, the rotor blade rows in the first channel and the associated corresponding rotor blade rows of the second channel are of identical design. Rotors commonly have a first rotor blade row in the first channel and also in the second channel, which are of identical design. Also of identical design are the rotor blades of the second rotor blade row in the first and second channels. These rotor blade rows of the first and second channels are rotor blade rows which correspond to one another in the sense that they change the thermodynamic variables of the flow medium in a substantially identical manner. 
         [0007]    The invention now proceeds from the idea that the corresponding rotor blade rows need not necessarily be of identical design. Rather, the invention proceeds from the idea of consciously forming the first channel and the second channel differently. To that end, the invention proposes making the configuration of the rotor blades of a rotor blade row of the first rotor section of different design to the configuration of the rotor blades of a rotor blade row of the second rotor section. This is to be understood as meaning that the mutually corresponding rotor blade rows are of different design to one another, the remaining mutually corresponding rotor blade rows being of substantially identical design. 
         [0008]    Further advantageous developments are provided in the subclaims. 
         [0009]    Thus, in a first advantageous development, the rotor blades of the final rotor blade row of the first rotor section are of different design to the rotor blades of the final rotor blade row of the second rotor section. For thermodynamic reasons, both in the first channel and in the second channel, the rotor blades of the final rotor blade row are the longest. The final rotor blade rows therefore have the greatest influence on the torsional vibrations of the rotor. Changing a rotor blade row therefore has a large effect on the entire rotor. 
         [0010]    In one advantageous development, the rotor blades of the various rotor blade rows differ with respect to their dynamic properties. 
         [0011]    In a further advantageous development, the rotor blades of the various rotor blade rows differ with respect to their elastic properties. In addition to the dynamic properties, elastic properties of the rotor blades also play an important part in influencing the torsional vibrations on a rotor. Changing the dynamic and/or elastic properties of the rotor blades would therefore lead to a large effect on the torsional vibrations. 
         [0012]    In a further advantageous development, the rotor blades of the various rotor blade rows differ with respect to their external geometry. 
         [0013]    Equally, in one advantageous development, the rotor blades of the various rotor blade rows are of different design with respect to their materials. Rotor blades which are of different design with respect to their geometry have a different frequency spectrum, such that rotor blade rows which are of different design with respect to their geometry have an effect on the torsional vibrations of a rotor. The density and further physical properties of the materials used have a great effect on the torsional vibrations. 
         [0014]    In advantageous developments, individual rotor blades are of different design. It is equally possible to change a plurality of individual rotor blades in a rotor blade row, or in various rotor blade rows, in order to thereby achieve a change in the torsional vibrations. 
         [0015]    In a further advantageous development, a plurality of rotor blade rows of the first rotor section are of different design to the rotor blade rows of the second section. The rotor blades of the various rotor blade rows may be of different design depending on which torsional vibrations are to be expected or damped. 
         [0016]    The invention will now be illustrated in more detail with reference to an exemplary embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The FIGURE shows, schematically, a cross-sectional view of a rotor according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0018]      FIG. 1  shows a cross-sectional view of a rotor  2  which is mounted such that it can rotate about an axis of rotation  1 . The rotor  2  is distinguished by a diameter  3 , rotor blades being arranged on the surface  4  of the rotor  2 . The rotor  2  shown in the FIGURE comprises a first rotor section  5  for a first channel. This first rotor section  5  comprises a first rotor blade row  7 , a second rotor blade row  8  and a final rotor blade row  9 . Further rotor blade rows are not shown for the sake of clarity. 
         [0019]    The second rotor section  6  also comprises a first rotor blade row  10 , corresponding to the first rotor blade row  7  of the first channel  14 , a second rotor blade row  11  and a final rotor blade row  12 . The first rotor blade row  7  and the rotor blade row  10  are mutually corresponding rotor blade rows. This means that, in accordance with the prior art, these two rotor blade rows are of substantially identical configuration. Accordingly, the second rotor blade row  8  and the second rotor blade row  11  are also mutually corresponding rotor blade rows. This is also the case for the final rotor blade row  9  and the final rotor blade row  12 , i.e. both rotor blade rows are mutually corresponding rotor blade rows. The individual rotor blade rows comprise a plurality of rotor blades which are arranged on the circumference of the rotor  2 . 
         [0020]    The configuration of the rotor blades of the final rotor blade row  9  is, according to the invention, of different design to the configuration of the rotor blades of the final rotor blade row  12  of the second rotor section  6 . By virtue of the fact that the configuration of the rotor blades in the rotor blade row  9  is of different design to the rotor blades of the rotor blade row  12 , the overall frequency behavior of the rotor  2  is different to the frequency behavior if the rotor blade rows had been of substantially identical design with respect to one another. 
         [0021]    The remaining rotor blade rows, i.e. the first rotor blade row  7  is correspondingly of substantially identical design to the rotor blade row  10 . 
         [0022]    In operation, fresh steam flows via a supply (not represented in more detail) into an inflow region  13  and from there splits into a first flow duct in the first rotor section  5  of the first channel and into a second flow duct  15  in the second rotor section  6  in the second channel. 
         [0023]    With respect to their dynamic properties and/or elastic properties, the rotor blades of the final rotor blade row  9  are of different design with respect to the rotor blades of the final rotor blade row  12 . To that end, the rotor blades of the various rotor blade rows are of different design with respect to their external geometry and/or the materials. 
         [0024]    By means of the change, according to the invention, of the configuration of the rotor blades of a rotor blade row, an additional degree of freedom is gained in order to change the torsion frequencies in a rotor  2 .