Abstract:
A helical seal system includes a first component, and a second component rotatable relative to the first component. The second component extends from a high pressure portion to a low pressure portion through an intermediate portion. A helical seal is provided on the intermediate portion of the second component. The helical seal includes at least one thread component having a pitch that is configured and disposed to draw fluids from the low pressure portion toward the high pressure portion when the second component is rotated.

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a helical seal for a turbomachine. 
     Gas turbomachines include a compressor portion linked to a turbine portion through a common compressor/turbine shaft and a combustor assembly. An inlet airflow is passed through an air intake toward the compressor portion. In the compressor portion, the inlet airflow is compressed through a number of sequential stages toward the combustor assembly. In the combustor assembly, the compressed airflow mixes with a fuel to form a combustible mixture. The combustible mixture is combusted in the combustor assembly to form hot gases. The hot gases are guided to the turbine portion through a transition piece. The hot gases expand through a number of turbine stages acting upon turbine buckets mounted on wheels to create work that is output, for example, to power a generator, a pump, or to provide power to a vehicle. 
     Additional gases, in the form of compressed air, flow from the compressor portion into the turbine portion for cooling. Seals are provided in the turbomachine to substantially isolate the hot gases and compressed airflow for cooling. Additional seals are positioned to prevent gases at a higher pressure leaking toward gases of a lower pressure without creating work resulting in a reduction in turbomachine efficiency. Other seals are provided about rotating components to prevent compressor airflow leakage. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the exemplary embodiment, a helical seal system includes a first component, and a second component rotatable relative to the first component. The second component extends from a higher pressure portion to a lower pressure portion through an intermediate portion. A helical seal is provided on the intermediate portion of the second component. The helical seal includes at least one thread component having a pitch that is configured and disposed to draw fluids from the lower pressure portion toward the higher pressure portion when the second component is rotated. 
     According to another aspect of the exemplary embodiment, a turbomachine includes a housing, a compressor portion, and a turbine portion operatively connected to the compressor portion. The turbine portion includes at least one turbine stage having a turbine spacer wheel. A shaft is arranged in the housing and is operatively connected to at least one of the compressor portion and the turbine portion. The shaft extends from a higher pressure portion to a lower pressure portion. A combustor assembly including at least one combustor is fluidically connected to the compressor portion and the turbine portion. A helical seal is provided on one of the shaft and the turbine spacer wheel. The helical seal includes at least one thread component having a pitch that is configured and disposed to draw fluids from the lower pressure portion toward the higher pressure portion when the one of the shaft and the turbine spacer wheel is rotated. 
     According to yet another aspect of the exemplary embodiment, a turbomachine system includes a first component and a second component rotatable relative to the first component. The second component extends from a high pressure portion to a low pressure portion through an intermediate portion. A helical seal is provided on the intermediate portion of the second component. The helical seal includes at least one thread component having a pitch that is configured and disposed to draw fluids from the low pressure end toward the high pressure end when the second component is rotated. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a partial cross-sectional schematic view of a turbomachine including a helical seal, in accordance with an exemplary embodiment; 
         FIG. 2  is a partial plan view of a shaft having a helical seal, in accordance with a first aspect of the exemplary embodiment; 
         FIG. 3  is a partial plan view of a shaft having a helical seal, in accordance with another aspect of the exemplary embodiment; 
         FIG. 4  is a partial plan view of a portion of a turbine spacer wheel having a helical seal, in accordance with yet another aspect of the exemplary embodiment; 
         FIG. 5  is a top view of the turbine spacer wheel of  FIG. 4 ; 
         FIG. 6  is a partial plan view of a turbine spacer wheel having a helical seal, in accordance with a yet still another aspect of the exemplary embodiment; and 
         FIG. 7  is a top view of the turbine spacer wheel of  FIG. 6 . 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A turbomachine in accordance with an exemplary embodiment is illustrated generally at  2 , in  FIG. 1 . Turbomachine  2  includes a housing  3  that supports a compressor portion  4  and a turbine portion  6 . Compressor portion  4  is mechanically linked to turbine portion  6  though a rotor  8  that extends from a forward (compressor) end  10  to an aft (turbine) end  11 . Rotor  8  includes an outer diametric surface component  12  that is provided with a first or forward bearing  13  and a second or aft bearing  14 . Rotor  8  is supported relative to a first shaft support component  15  (first component) and a second shaft support component  16  (second component). More specifically, first and second bearings  13  and  14  provide an interface between rotor  8  and respective ones of first and second shaft support components  15  and  16 . Turbomachine  2  also includes a combustor assembly  19  having one or more combustors  22 . 
     Air enters compressor portion  4  through an inlet (not separately labeled). The air passes through a plurality of compressor stages (also not separately labeled) toward turbine portion  6  and combustor  22 . Compressed air enters combustor  22  and mixes with fuel to form a combustible mixture. The combustible mixture combusts forming hot gases that flow along a hot gas path  24  of turbine portion  6 . The hot gases expand through a number of turbine stages  28  toward an exhaust  29 . In the exemplary embodiment shown, the hot gases expand through a first stage  30 , a second stage  32 , and a third stage  34 . First stage  30  includes a first plurality of nozzle components  37  and blade components  38 . Second stage  32  includes a second plurality of nozzle components  40  and blade components  41 , and third stage  34  includes a third plurality of nozzle components  43  and blade components  44 . Nozzle components  37 ,  40  and  43  guide the hot gases toward respective ones of blade components  38 ,  41  and  44 . The hot gases impinge upon the blade components  38 ,  41  and  44  creating a rotational force that is passed to a driven system, such as a generator, a pump or the like (not shown). 
     Turbine portion  6  also includes a first turbine spacer wheel  47  having an outer diametric surface sealing component  48  (first component) and a second turbine spacer wheel  49  having an outer diametric surface sealing component  50  (second component). First and second turbine spacer wheels  47  and  49  are interposed between adjacent turbine wheels (not separately labeled). First turbine spacer wheel  47  is positioned between first and second stages  30  and  32  and second turbine spacer wheel  49  is positioned between second and third stages  32  and  34 . Each outer diametric surface sealing components  48  and  50  includes a helical seal  55  ( FIG. 4 ) which, as will be detailed more fully below, reduces leakage flow from higher pressure portions to lower pressure portion in turbine portion  6 . Turbomachine  2  also includes a helical seal  60  arranged at forward end  10  of rotor  8 . Helical seal  60  reduces lubricant or other leakage between outer diametric surface  12  and shaft support  15 . Turbomachine  2  may also include a high pressure packing seal  61  having a helical seal  62 . An additional helical seal (not separately labeled) is provided at aft end  11 . 
     As best shown in  FIG. 2 , helical seal  60  includes a thread component  63  that extends from a first end  64  to a second end (not shown) arranged on an opposing side of rotor  8 . Thread component  63  includes a plurality of thread sections, one of which is indicated at  66 . Thread component  63  includes a pitch (not separately labeled) that, when rotated, draws or pumps fluid, such as air, along outer diametric surface  12 . In accordance with one aspect of the exemplary embodiment, thread component  63  includes a pitch that pumps fluid from a low pressure portion of rotor  8  to a high pressure portion of rotor  8  to reduce leakage from high pressure portions to low pressure portions along outer diametric surface  12 . The particular angle of the pitch may vary depending upon the position of helical seal  60 . In accordance with another aspect of the exemplary embodiment, thread component  63  is materially integrally formed with outer diametric surface  12 . More specifically, thread component  63  is machined into rotor  8 . However, it should be understood, that thread component  63  may be formed on a separate sleeve-like component that is secured to outer diametric surface  12 . 
       FIG. 3 , in which like reference numbers represent corresponding parts in the respective views, illustrates a helical seal  80 , in accordance with another aspect of the exemplary embodiment. Helical seal  80  includes a first thread component  82  (first component) and a second thread component  83  (second component). First thread component  82  extends from a first end  85  to a second end (not shown) and includes a plurality of thread sections, one of which is indicated at  87 . Second thread component  83  extends from a first end (not shown) to a second end  90  and includes a plurality of thread portions, one of which is indicated at  91 . Thread portions  91  are arranged between adjacent ones of thread sections  87 . 
     In a manner similar to that described above, first thread component  82  and second thread component  83  each includes a pitch (not separately labeled) that pumps fluid from a low pressure portion of rotor  8  to a high pressure portion of rotor  8  to reduce ambient air ingestion along outer diametric surface  12 . The particular angle of the pitch may vary depending upon the position of helical seal  80 . In accordance with another aspect of the exemplary embodiment, first and second thread components  82  and  83  are materially integrally formed with outer diametric surface  12 . More specifically, first thread component  82  and second thread component  53  are machined into rotor  8 . However, it should be understood, that first thread component  83  and second thread component  83  may be formed on a separate sleeve-like component that is secured to outer diametric surface  12 . 
     Reference will now follow to  FIGS. 4 and 5 , wherein like reference numbers represent corresponding parts in the respective views, in describing helical seal  55 . Helical seal  55  includes a thread component  113  that extends from a first end  115  to a second end  116 . Thread component  113  includes a plurality of thread sections, one of which is indicated at  117 . Thread component  113  includes a pitch (not separately labeled) that, when rotated, draws or pumps fluid, such as air, along outer diametric surface  48  from a lower pressure portion to a higher pressure portion. 
     In accordance with one aspect of the exemplary embodiment, thread component  113  includes a pitch (not separately labeled) that creates a reverse fluid flow across outer diametric surface  48 . More specifically, the fluid flows from a low pressure portion to a high pressure portion of wheelspace portion  51  to reduce leakage flow from turbine portion  6 . The particular angle of the pitch may vary. In accordance with another aspect of the exemplary embodiment, thread component  113  is materially integrally formed with outer diametric surface component  48 . More specifically, thread component  113  is machined into outer diametric surface component  48 . However, it should be understood, that thread component  113  may be formed on a separate sleeve-like component that is secured to first turbine spacer wheel  47 . 
     Reference will now follow to  FIGS. 6 and 7 , wherein like reference numbers represent corresponding parts in the respective views, in describing helical seal  134 , in accordance with another exemplary embodiment. Helical seal  134  includes a first thread component  137  and a second thread component  138 . First thread component  137  extends from a first end  142  to a second end  143  and includes a plurality of thread sections, one of which is indicated at  144 . Second thread component  138  extends from a first end  145  to a second end  146  and includes a plurality of thread portions, one of which is indicated at  150 . Thread portions  150  are arranged between adjacent ones of thread sections  144 . 
     In a manner similar to that described above, first thread component  137  and second thread component  138  each includes a pitch (not separately labeled) that pumps fluid from a low pressure portion to a high pressure portion of wheelspace portion  51  to reduce leakage flow. The particular angle of the pitch may vary. In accordance with another aspect of the exemplary embodiment, first and second thread components  137  and  138  are materially integrally formed with outer diametric surface  48 . More specifically, first and second thread components  137  and  137  are machined into first turbine spacer wheel  47 . However, it should be understood, that first thread component  137  and second thread component  138  may be formed on a separate sleeve-like component that is secured to first turbine spacer wheel  47 . 
     At this point it should be understood that the exemplary embodiments describe a helical seal that creates a reverse fluid flow to opposed leakage fluid in a turbomachine. The particular pitch of the helical seal may vary. The number and geometry of the thread components may also vary. Further, the location of the helical seal may vary and should not be considered to be limited to the particular arrangement shown. More specifically, the helical seal may be positioned as a turbine inter-stage seal, as shown in  FIG. 4 , a bearing seal, as shown in  FIG. 2 , and high pressure packing seal or other type of seal in the turbomachine. Finally, the helical seal may be materially integrally formed with one of the components to be sealed, or may be formed on a separate component that is joined to one of the components to be sealed. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.