Abstract:
An integrally bladed rotor for a gas turbine engine includes at least one discontinuity formed in an outer face of an outer rim. The discontinuity reduces hoop stress in the outer rim.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This application relates to an integrally bladed rotor, such as utilized in gas turbine engines, wherein an outer rim has a discontinuity. 
         [0002]    Gas turbine engines typically include a plurality of sections mounted in series. A fan section may deliver air to a compressor section. The compressor section may include high and low compression stages, and delivers compressed air to a combustion section. The air is mixed with fuel in the combustion section and burned. Products of this combustion are passed downstream over turbine rotors. 
         [0003]    The compressor section includes a plurality of rotors having a plurality of circumferentially spaced blades. Recently, these rotors and blades have been formed as an integral component, called an “integrally bladed rotor.” 
         [0004]    In one known integrally bladed rotor, blades extend from an outer rim. The outer rim in integrally bladed rotors is subject to a number of stresses, and in particular, hoop stresses. The hoop stresses can cause the life of the integrally bladed rotor to be reduced due to thermal fatigue. 
       SUMMARY OF THE INVENTION 
       [0005]    In the disclosed embodiment of this invention, discontinuities are formed in the outer rim of an integrally bladed rotor. In the disclosed embodiment, the discontinuity extends through the entire axial and radial width of the outer rim. 
         [0006]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  schematically shows a gas turbine engine. 
           [0008]      FIG. 2  shows an integrally bladed rotor according to an embodiment of the present invention. 
           [0009]      FIG. 3  shows a detail of the inventive integrally bladed rotor. 
           [0010]      FIG. 4  is a perspective view of the  FIG. 3  integrally bladed rotor. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]      FIG. 1  shows a gas turbine engine  10 . As known, a fan section  14  moves air and rotates about an axial center line  12 . A compressor section  16 , a combustion section  18 , and a turbine section  20  are also centered on the axial center line  12 .  FIG. 1  is a highly schematic view; however, it does show the main components of the gas turbine engine. Further, while a particular type of gas turbine engine is illustrated in  FIG. 1 , it should be understood that the present invention extends to other types of gas turbine engines. 
         [0012]      FIG. 2  shows an integrally bladed rotor  80 , such as may be utilized for the high stage compression section. The integrally bladed rotor  80  includes an outer rim  82 , a plurality of circumferentially distributed blades  84 , a central hub  48 , and a plurality of channels  86 . The channels  86  extend through the axial width of the rotor  80 . Channels  86  and discontinuities  88 ,  90  and  92  (see  FIGS. 3 and 4 ) address the hoop stresses discussed earlier. 
         [0013]      FIG. 3  shows integrally bladed rotor  80 . In integrally bladed rotor  80 , a discontinuity  88 ,  90 ,  92  is formed through a radial extent of the outer rim  82 . As shown, a central enlarged, seal holding portion  90  is formed between two smaller slots  88  and  92 . As can be appreciated, the radially inner slot  92  extends to the channel  86 . 
         [0014]    As shown in  FIG. 4 , the outer slot  88  extends across the axial width of the rotor  80 . Seals  96  may be inserted in the enlarged portion  90  of the discontinuity. The seal  96  is shown as a wire seal, however, other seals, such as brush seals or W seals, may be utilized. The seals prevent recirculation of gases from the radially outer face of the outer rim  82  into the channels  86 . 
         [0015]    Although embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.