Patent Publication Number: US-8979486-B2

Title: Intersegment spring “T” seal

Description:
BACKGROUND 
     The present disclosure relates to gas turbine engines, and in particular, to an intersegment seal assembly therefor. 
     Feather seals are commonly utilized in aerospace and other industries to provide a seal between two adjacent components. For example, gas turbine engine vanes are arranged in a circumferential configuration to form an annular vane ring structure about an engine axis. Typically, each stator segment includes an airfoil and a platform section. When assembled, the platforms abut and define a radially inner and radially outer boundary to a core airflow path. 
     Typically, the edge of each platform includes a channel which receives a feather seal assembly that seals the hot gas core airflow from a surrounding medium such as a cooling airflow. Radial leakage through intersegment gaps within the high compressor may lead to loss in efficiency and stability. With the introduction of smaller clusters and singlets, the number of intersegment gaps and leakage potential therefrom has increased. 
     SUMMARY 
     A spring seal assembly according to an exemplary aspect of the present disclosure includes a split body portion with a first leg and a second leg that extend away from a plane. A projection portion which extends from the split body portion within the plane. 
     In a further non-limiting embodiment of any of the foregoing spring seal assembly embodiments, the first leg and the second leg may define a “V” shape. 
     In a further non-limiting embodiment of any of the foregoing spring seal assembly embodiments, the projection portion may be twice the thickness of the first leg and the second leg. 
     In a further non-limiting embodiment of any of the foregoing spring seal assembly embodiments, the split body may be formed by a first member and a second member joined along the plane. 
     In a further non-limiting embodiment of any of the foregoing spring seal assembly embodiments, the first member and the second member may be formed of a steel alloy. 
     In a further non-limiting embodiment of any of the foregoing spring seal assembly embodiments, the end sections of the first leg and the second leg may be curved toward the plane. 
     A compressor section of a gas turbine engine according to another exemplary aspect of the present disclosure includes a multiple of arcuate vane support segments defined about an engine axis, and a spring seal between each pair of the multiple of arcuate vane support segments. 
     In a further non-limiting embodiment of any of the foregoing compressor section embodiments, the spring seal may define a first leg and a second leg that extend away from a plane which contains the engine axis. 
     In a further non-limiting embodiment of any of the foregoing compressor section embodiments, the first leg and the second leg may define a “V” shape. 
     In a further non-limiting embodiment of any of the foregoing compressor section embodiments, the spring seal may define a projection portion and the multiple of arcuate vane support segments may define a projection. The projection portion and the projection may fit within an annular slot around the engine axis. 
     In a further non-limiting embodiment of any of the foregoing compressor section embodiments, the slot may be formed between a full ring case section and an air seal. 
     A method of sealing a compressor section of a gas turbine engine according to an exemplary aspect of the present disclosure includes compressing a spring seal between each pair of a multiple of arcuate vane support segments about an engine axis. 
     In a further non-limiting embodiment of any of the foregoing methods, the method may include circumferentially mounting the multiple of arcuate vane support segments. 
     In a further non-limiting embodiment of any of the foregoing methods, the method may include mounting the spring seal in the same manner as the multiple of arcuate vane support segments. 
     In a further non-limiting embodiment of any of the foregoing methods, the method may include mounting the spring seal and the multiple of arcuate vane support segments in a common annular slot. 
     In a further non-limiting embodiment of any of the foregoing methods, the method may include mounting the spring seal and the multiple of arcuate vane support segments in two opposed annular slots. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  is a schematic cross-sectional view of a gas turbine engine; 
         FIG. 2  is an expanded view of a compressor section of the gas turbine engine; 
         FIG. 3  is an frontal view of a spring seal mounted between two representative segments; 
         FIG. 4  is a perspective view of a spring seal; and 
         FIG. 5  is an expanded axial sectional view of a mounted spring seal. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section  22  drives air along a bypass flowpath while the compressor section  24  drives air along a core flowpath for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines. 
     The engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine static structure  36  via several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided. 
     The low speed spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor  44  and a low pressure turbine  46 . The inner shaft  40  is connected to the fan  42  through a geared architecture  48  to drive the fan  42  at a lower speed than the low speed spool  30 . The high speed spool  32  includes an outer shaft  50  that interconnects a high pressure compressor  52  and high pressure turbine  54 . A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes. 
     The core airflow is compressed by the low pressure compressor  44  then the high pressure compressor  52 , mixed and burned with fuel in the combustor  56 , then expanded over the high pressure turbine  54  and low pressure turbine  46 . The turbines  54 ,  46  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. 
     With reference to  FIG. 2 , the high pressure compressor  52  generally includes a rotor assembly  60  with a drum rotor  62  that supports arrays of rotor blades  64  which extend outward across the core airflow path C and a stator assembly  66  that extends circumferentially about the rotor assembly  60  and extends axially to bound the core airflow path C. The stator assembly  66  generally includes arrays of stator vane assemblies  68  disposed between the arrays of rotor blades  64 . Each array of stator vane assemblies  68  extends inward across the core airflow path C. It should be appreciated that although a section of the HPC is disclosed herein in the illustrated non-limiting embodiment, other sections of the engine will benefit herefrom. 
     The stator assembly  66  includes outer air seals  80  which, in the disclosed non-limiting embodiment, are of a “T” cross-section. The outer air seals  80  may be full rings or arcuate segments. The base  82  of the “T” extends radially outwardly while a head  84  of each “T” extends substantially parallel to the core airflow path. An abradable seal  86  may be secured within the outer air seal  80  to bound each array of rotor blades  64 . 
     The outer air seals  80  at least partially support a multiple of arcuate vane support segments  88 . Each arcuate vane support segment  88  may include one or more stator vane airfoils  90  (also shown in  FIG. 3 ). The stator vane airfoils  90  extend inwardly from the vane support segment  88  and terminate in an inner shroud  92 . The inner shroud  92  may support a damper  94  with an abradable air seal  96  which interface with knife edges  98  on the drum rotor  62  to provide an airflow seal. 
     Each arcuate vane support segment  88  include axial projections  100  which fit against an outer surface of the air seal  80  and are entrapped against an inner surface of a full ring case section  102 . Each full ring case section  102  includes flanges  104  to interface with the base  82  of a respective air seal  80  and is attached thereto with a fastener  106 . An annular slot  108  defined about the engine axis A is thereby formed between the full ring case section  102  and the air seal  80  into which the projections  100  are received. The multiple of arcuate vane support segments  88  are axially and radially supported to be circumferentially arranged and collectively form the full, annular ring of stator vane airfoils  90  about the axis A. 
     With reference to  FIG. 3 , a spring seal  110  is located between each pair of arcuate vane support segments  88 . The spring seal  110  is shaped generally the same as the cross-section of the arcuate vane support segments  88 . That is, the spring seal  110  fits within the annular slot  108  ( FIG. 2 ). 
     With reference to  FIG. 4 , the spring seal  110  may be manufactured of two members  111 A,  111 B such as a steel alloy sheet which are welded, brazed or otherwise attached together to form a split body portion  112  and a projection portion  114  which extend from the split body portion  112 . The split body portion  112  is defined by a first leg  116 A and a second leg  116 B which define a generally “V” shape in cross section. That is, the first leg  116 A and the second leg  116 B extend away from a central plane P which contains the joint J between the two members  111 A,  111 B. Curved edges  118  may be further provided which extend at least somewhat toward the plane P. 
     The projection portion  114  is formed by both members  111 A,  111 B and extends from the first leg  116 A and the second leg  116 B within the plane P. That is, the projection portion  114  are twice the thickness of the first leg  116 A and the second leg  116 B as the projections are formed by both members  111 A,  111 B while the first leg  116 A and the second leg  116 B are each formed by one member  111 A,  11 B. The projection portion  114  allows the spring seal  110  to be mounted in the same manner as the arcuate vane support segments  88  to which they abut ( FIG. 5 ). 
     On assembly the loaded spring seal  110  is compressed by the adjacent arcuate vane support segments  88  to yield a tight intersegment gap between the adjacent arcuate vane support segments  88  and damping thereof. Pressure from within the core airflow path further loads the spring seal  110  and tends to open the first leg  116 A and the second leg  116 B to further facilitate the seal. This results in an increased surge margin attributed to the more effective seal. 
     The radial gap could be reduced up to thirty times as compared to some standard configurations. For stator singlets, the radial gap may be reduced approximately eight times for all  140  or so intersegment interfaces which results in significant leakage reductions as compared to conventional feather seals. Also, unlike feather seals, the spring seals  110  require no machining of the stators and may reduce the weight of stators as no feather seal bosses are required. 
     The spring seals  110  may also be utilized with singlets where feather seals may not be possible. As the spring seals  110  also slide into the case there would be much less FOD risk than feather seals. Furthermore, for small clusters and singlets the spring seals  110  prevent excessive circumferential stacking against anti-rotation features that result in several large gaps around the stage which may reduce stability. 
     It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting. 
     Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
     It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
     The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.