Patent Publication Number: US-6904757-B2

Title: Mounting assembly for the forward end of a ceramic matrix composite liner in a gas turbine engine combustor

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
   The U.S. Government may have certain rights in this invention pursuant to contract number NAS3-27720. 

   BACKGROUND OF THE INVENTION 
   The present invention relates generally to the use of Ceramic Matrix Composite (CMC) liners in a gas turbine engine combustor and, in particular, to the mounting of such CMC liners to the dome and cowl of the combustor so as to accommodate differences in thermal growth therebetween. 
   It will be appreciated that the use of non-traditional high temperature materials, such as Ceramic Matrix Composites (CMC), are being studied and utilized as structural components in gas turbine engines. There is particular interest, for example, in making combustor components which are exposed to extreme temperatures from such material in order to improve the operational capability and durability of the engine. As explained in U.S. Pat. No. 6,397,603 to Edmondson et al., substitution of materials having higher temperature capabilities than metals has been difficult in light of the widely disparate coefficients of thermal expansion when different materials are used in adjacent components of the combustor. This can result in a shortening of the life cycle of the components due to thermally induced stresses, particularly when there are rapid temperature fluctuations which can also result in thermal shock. 
   Accordingly, various schemes have been employed to address problems that are associated with mating parts having differing thermal expansion properties. As seen in U.S. Pat. No. 5,291,732 to Halila, U.S. Pat. No. 5,291,733 to Halila, and U.S. Pat. No. 5,285,632 to Halila, an arrangement is disclosed which permits a metal heat shield to be mounted to a liner made of CMC so that radial expansion therebetween is accommodated. This involves positioning a plurality of circumferentially spaced mount pins through openings in the heat shield and liner so that the liner is able to move relative to the heat shield. 
   U.S. Pat. No. 6,397,603 to Edmondson et al. also discloses a combustor having a liner made of Ceramic Matrix Composite materials, where the liner is mated with an intermediate liner dome support member in order to accommodate differential thermal expansion without undue stress on the liner. The Edmondson et al. patent further includes the ability to regulate part of the cooling air flow through the interface joint. 
   While each of the aforementioned patents reveals mounting arrangements for a CMC liner which are useful for their particular combustor designs, none involve a liner made of CMC materials being connected directly to the dome and cowl portions of the combustor in a single mounting arrangement. Thus, it would be desirable for a simple mounting assembly to be developed for a liner having a different coefficient of thermal expansion than the components to which it is mated. It would also be desirable for such mounting assembly to permit improved flow of air around such interface while minimizing changes in the combustor structure over previous configurations. 
   BRIEF SUMMARY OF THE INVENTION 
   In a first exemplary embodiment of the invention, a mounting assembly for a forward end of a liner in a combustor of a gas turbine engine including a dome and a cowl is disclosed, wherein a longitudinal centerline axis extends through the gas turbine engine. The mounting assembly includes a pin member extending through each one of a plurality of circumferentially spaced openings formed in the forward end of the liner, an aft portion of the cowl, and a portion of the dome, with each pin member including a head portion at one end thereof. A nut is adjustably connected to an end of each pin member opposite the head portion. A bushing is located on each pin member at a position intermediate the head portion and the nut, wherein the openings in the liner forward end are sized to fit around the bushings. In this way, the cowl aft portion and the dome portion are fixedly connected together between the bushing and the nut so that the bushings are able to slide radially through the openings in the liner forward end as the cowl and the dome experience thermal growth greater than the liner. 
   In a second exemplary embodiment of the invention, a combustor for a gas turbine engine having a longitudinal centerline axis extending therethrough is disclosed as including: an outer liner having a forward end and an aft end, where the outer liner is made of a ceramic matrix composite material; an annular dome having an outer portion and an inner portion, where the dome is made of a metal; a plurality of fuel/air mixers connected to and circumferentially spaced within the dome; an outer cowl located forward of the dome outer portion having a forward end and an aft end, where the outer cowl is made of a metal; and, an assembly for mounting the outer liner to the outer cowl and the dome outer portion, wherein the outer cowl and the dome outer portion are fixedly connected together and movably connected to the outer liner in a radial direction as the outer cowl and the dome outer portion experience thermal growth greater than the outer liner. 
   In accordance with a third exemplary embodiment of the invention, a combustor for a gas turbine engine having a longitudinal centerline axis extending therethrough is disclosed as including: an inner liner having a forward end and an aft end, where the inner liner is made of a ceramic matrix composite material; an annular dome having an outer portion and an inner portion, where the dome is made of a metal; a plurality of fuel/air mixers connected to and circumferentially spaced within the dome; an inner cowl located forward of the dome inner portion having a forward end and an aft end, where the inner cowl is made of a metal; and, an assembly for mounting the inner liner to the inner cowl and the dome inner portion, wherein the inner cowl and said dome inner portion are fixedly connected together and movably connected to the inner liner in a radial direction as the inner cowl and the dome inner portion experience thermal growth greater than the inner liner. 
   In accordance with a fourth exemplary embodiment of the invention, a method of mounting a liner to a dome and a cowl in a gas turbine engine combustor having a longitudinal centerline axis therethrough is disclosed, wherein the liner is made of a material having a lower coefficient of thermal expansion than the dome and the cowl. The method includes the steps of fixedly connecting an aft portion of the cowl and a portion of the dome and connecting a forward end of the liner to the cowl aft portion and the dome portion in a manner so as to permit radial movement of the cowl aft end and the dome portion with respect to the liner forward end. The method may also include the step of connecting the forward end of the liner to the cowl aft portion and the dome portion in a manner so as to prevent axial and/or circumferential movement of the cowl aft end and the dome portion with respect to the liner forward end. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a longitudinal cross-sectional view of a gas turbine engine combustor including an outer liner and an inner liner mounted in accordance with the present invention; 
       FIG. 2  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where an embodiment of the mounting assembly for a forward end of the outer liner is shown prior to any thermal growth experienced by the outer liner, the outer cowl aft end and the dome outer portion; 
       FIG. 3  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where the embodiment of the mounting assembly for a forward end of the outer liner of  FIG. 2  is shown after thermal growth is experienced by the outer liner, the outer cowl aft end and the dome outer portion; 
       FIG. 4  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where an embodiment of the mounting assembly for a forward end of the inner liner is shown prior to any thermal growth experienced by the inner liner, the inner cowl aft end and the dome inner portion; 
       FIG. 5  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where the embodiment of the mounting assembly for a forward end of the inner liner of  FIG. 4  is shown after thermal growth is experienced by the inner liner, the inner cowl aft end and the dome inner portion; 
       FIG. 6  is a perspective view of a drag link depicted in  FIG. 1 ; 
       FIG. 7  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where an alternative embodiment of the mounting assembly for a forward end of the inner liner is shown prior to any thermal growth experienced by the inner liner, the inner cowl aft end and the dome inner portion; 
       FIG. 8  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where the alternative embodiment of the mounting assembly for a forward end of the inner liner of  FIG. 7  is shown after thermal growth is experienced by the inner liner, the inner cowl aft end and the dome inner portion; 
       FIG. 9  is a partial exploded perspective view of the mounting assembly depicted in  FIGS. 7 and 8  prior to the nut being positioned on the pin member; 
       FIG. 10  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where a second alternative embodiment of the mounting assembly for a forward end of the inner liner is shown prior to any thermal growth experienced by the inner liner, the inner cowl aft end and the dome inner portion; and, 
       FIG. 11  is an enlarged, partial cross-sectional view of the combustor depicted in  FIG. 1 , where the second alternative embodiment of the mounting assembly for a forward end of the inner liner of  FIG. 10  is shown after thermal growth is experienced by the inner liner, the inner cowl aft end and the dome inner portion. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings in detail, wherein identical numerals indicate the same elements throughout the figures,  FIG. 1  depicts an exemplary gas turbine engine combustor  10  which conventionally generates combustion gases that are discharged therefrom and channeled to one or more pressure turbines. Such turbine(s) drive one or more pressure compressors upstream of combustor  10  through suitable shaft(s). A longitudinal or axial centerline axis  12  is provided through the gas turbine engine for reference purposes. 
   It will be seen that combustor  10  further includes a combustion chamber  14  defined by an outer liner  16 , an inner liner  18  and a dome  20 . Combustor dome  20  is shown as being single annular in design so that a single circumferential row of fuel/air mixers  22  are provided within openings formed in such dome  20 , although a multiple annular dome may be utilized. A fuel nozzle (not shown) provides fuel to fuel/air mixers  22  in accordance with desired performance of combustor  10  at various engine operating states. It will also be noted that an outer annular cowl  24  and an inner annular cowl  26  are located upstream of combustion chamber  14  so as to direct air flow into fuel/air mixers  22 , as well as an outer passage  28  between outer liner  16  and an outer casing  30  and an inner passage  32  between inner liner  18  and an inner casing  31 . An inner annular support member  34  is further shown as being connected to a nozzle support  33  by a plurality of bolts  37  and nuts  39 . In this way, convective cooling air is provided to the outer and inner surfaces of outer and inner liners  16  and  18 , respectively, and air for film cooling is provided to the inner and outer surfaces of such liners. A diffuser (not shown) receives the air flow from the compressor(s) and provides it to combustor  10 . 
   It will be appreciated that outer and inner liners  16  and  18  are preferably made of a Ceramic Matrix Composite (CMC), which is a non-metallic material having high temperature capability and low ductility. Exemplary composite materials utilized for such liners include silicon carbide, silicon, silica or alumina matrix materials and combinations thereof. Typically, ceramic fibers are embedded within the matrix such as oxidation stable reinforcing fibers including monofilaments like sapphire and silicon carbide (e.g., Textron&#39;s SCS-6), as well as rovings and yarn including silicon carbide (e.g., Nippon Carbon&#39;s NICALON®, Ube Industries&#39; TYRANNO®, and Dow Corning&#39;s SYLRAMIC®), alumina silicates (e.g., Nextel&#39;s 440 and 480), and chopped whiskers and fibers (e.g., Nextel&#39;s 440 and SAFFIL®), and optionally ceramic particles (e.g., oxides of Si, Al, Zr, Y and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite and montmorillonite). CMC materials typically have coefficients of thermal expansion in the range of about 1.3×10 −6  in/in/° F. to about 3.5×10 −6  in/in/° F. in a temperature of approximately 1000-1200° F. 
   By contrast, dome  20 , outer cowl  24 , and inner cowl  26  are typically made of a metal, such as a nickel-based superalloy (having a coefficient of thermal expansion of about 8.3-8.5×10 −6  in/in/° F. in a temperature of approximately 1000-1200° F.) or cobalt-based superalloy (having a coefficient of thermal expansion of about 7.8-8.1×10 −6  in/in/° F. in a temperature of approximately 1000-1200° F.). Thus, liners  16  and  18  are better able to handle the extreme temperature environment presented in combustion chamber  14  due to the materials utilized therefor, but attaching them to the different materials utilized for dome  20  and cowls  24  and  26  presents a separate challenge. Among other limitations, components cannot be welded to the CMC material of outer and inner liners  16  and  18 . 
   Accordingly, it will be seen in  FIGS. 2 and 3  that a mounting assembly  35  is provided for forward end  36  of outer liner  16 , an aft portion  38  of outer cowl  24 , and an outer portion  40  of dome  20  so as to accommodate varying thermal growth experienced by such components. It will be appreciated that the mounting arrangement shown in  FIG. 2  is prior to any thermal growth experienced by outer liner  16 , outer cowl aft portion  38  and dome outer portion  40 . As seen in  FIG. 3 , however, outer liner  16 , outer cowl aft portion  38  and dome outer portion  40  have each experienced thermal growth, with outer cowl aft portion  38  and dome outer portion  40  having experienced greater thermal growth than outer liner  16  due to their higher coefficients of thermal expansion. Accordingly, outer cowl aft portion  38  and dome outer portion  40  are depicted as being permitted to slide or move in a radial direction with respect to longitudinal centerline axis  12  toward outer liner  16 . 
   More specifically, it will be understood that outer liner forward end  36 , outer cowl aft portion  38  and dome outer portion  40  each include a plurality of circumferentially spaced openings  42 ,  44  and  46 , respectively, which are positioned so as to be in alignment. A pin member  48  preferably extends through each set of aligned openings and includes a head portion  50  at a first end thereof. Pin members  48  preferably include threads  52  formed thereon so that a nut  54  is adjustably connected to a second end of each pin member  48  opposite head portion  50 . It will be noted that each nut  54  preferably includes a flange portion  56  extending from an outer surface  58  thereof. A bushing  60  is also preferably located on each pin member  48  and fixed at a position intermediate head portion  50  and nut  54  between head portion  50  and dome outer portion  40 . In this way, nuts  54  and head portions  50  fixedly connect together cowl aft portion  38 , dome outer portion  40  and bushings  60 . It will be understood that while dome outer portion  40  is located between outer cowl aft portion  38  and bushings  60 , combustor  10  could be configured so that outer cowl aft portion  38  is located between dome outer portion  40  and bushings  60 . 
   Openings  42  in outer liner forward end  36  are preferably sized, however, so that bushings  60  are able to slide radially therethrough as outer cowl aft portion  38  and dome outer portion  40  experience greater thermal growth than outer liner forward end  36 . Thus, outer cowl aft portion  38  and dome outer portion  40  are able to move between a first radial position (see  FIG. 2 ) and a second radial position (see FIG.  3 ). As seen in the figures, a height  66  of bushings  60  should be sized great enough to accommodate the radial thermal growth of outer cowl aft portion  38  and dome outer portion  40 . In order to provide the clamping of bushings  60  with dome outer portion  40  and outer cowl aft portion  38 , however, pin head portion  50  will have a diameter  62  greater than a diameter  61  of opening  63  in bushings  60 . 
   It is preferred that cowl aft portion  38  and dome outer portion  40  not be able to move axially or circumferentially with respect to outer liner forward end  36 . Accordingly, an annular member  68  (which preferably may include a plurality of arcuate segments) having a channel  70  formed therein is provided adjacent cowl aft portion  38 . A plurality of circumferentially spaced openings  72  are formed in annular member  68  which are aligned with openings  42  in outer liner forward end  36 , openings  44  in outer cowl aft portion  38  and openings  46  in dome outer portion  40 . Nuts  54  are then positioned so that flange portions  56  thereof are located within channel  70  and fixedly connect outer cowl aft portion  38 , dome outer portion  40 , bushings  60  and annular member  68 . 
   It will also be seen that outer cowl  24  is configured in a manner to accommodate mounting assembly  35 . More specifically, outer cowl  24  includes a forward portion  74 , aft portion  38 , and an intermediate portion  76 . Outer cowl aft portion  38  is preferably a flange which is stepped from outer cowl intermediate portion  76  by an amount substantially equivalent to height  66  of bushings  60  as seen by surface  78 . It will also be understood that outer cowl intermediate portion  76  is configured to shield mounting assembly  35 , and specifically bushings  60 , from undesirable air flow entering outer passage  28 . 
   Similarly, it will be seen in  FIG. 4  that a mounting assembly  80  is provided for a forward end  82  of inner liner  18 , an aft portion  84  of inner cowl  26 , and an inner portion  86  of dome  20  so as to accommodate differences in thermal growth experienced by such components. It will be appreciated that the mounting assembly shown in  FIG. 4  is prior to any thermal growth experienced by inner liner  18 , inner cowl aft portion  84  and dome inner portion  86 . As seen in  FIG. 5 , inner liner  18 , inner cowl aft portion  84  and dome inner portion  86  have each experienced thermal growth, with inner cowl aft portion  84  and dome inner portion  86  having experienced greater thermal growth than inner liner  18  due to their higher coefficients of thermal expansion. Accordingly, inner cowl aft portion  84  and dome inner portion  86  are depicted as being permitted to slide or move in a radial direction with respect to longitudinal centerline axis  12  away from inner liner  18 . 
   More specifically, it will be understood that inner liner forward end  82 , inner cowl aft portion  84  and dome inner portion  86  each include a plurality of circumferentially spaced openings  88 ,  90  and  92 , respectively, which are positioned so as to be in alignment. A pin member  94  preferably extends through each set of aligned openings and includes a head portion  96  at a first end thereof. Pin members  94  preferably include threads  98  formed thereon so that a nut  100  is adjustably connected to a second end of each pin member  94  opposite head portion  96 . It will be noted that each nut  100  preferably includes a flange portion  102  extending from an outer surface  104  thereof. A bushing  106  is also preferably located on each pin member  94  and fixed at a position intermediate head portion  96  and nut  100  between head portion  96  and inner cowl aft portion  84 . In this way, nuts  100  and head portions  96  fixedly connect together inner cowl aft portion  84 , dome inner portion  86  and bushings  106 . It will be understood that while inner cowl aft portion  84  is located between dome inner portion  86  and bushings  106 , combustor  10  could be configured so that dome inner portion  86  is located between inner cowl aft portion  84  and bushings  106 . 
   Openings  88  in inner liner forward end  82  are preferably sized, however, so that bushings  106  are able to slide radially therethrough as inner cowl aft portion  84  and dome inner portion  86  experience thermal growth greater than inner liner forward end  82 . Thus, inner cowl aft portion  84  and dome inner portion  86  are able to move between a first radial position (see  FIG. 4 ) and a second radial position (see FIG.  5 ). As seen in the figures, a height  112  of bushings  106  should be sized great enough to accommodate the radial thermal growth of inner cowl aft portion  84  and dome inner portion  86 . In order to provide the clamping of bushings  106  with inner cowl aft portion  84  and dome inner portion  86 , however, pin head portion  96  will have a diameter  108  greater than a diameter  110  of an opening  111  in bushings  106 . 
   It is preferred that inner cowl aft portion  84  and dome inner portion  86  not be able to move axially or circumferentially with respect to inner liner forward end  82 . Accordingly, an annular member  114  having a channel  116  formed therein is provided adjacent dome inner portion  86 . A plurality of circumferentially spaced openings  118  are formed in annular member  114  which are aligned with openings  88  in inner liner forward end  82 , openings  90  in inner cowl aft portion  84  and openings  92  in dome inner portion  86 . Nuts  100  are then positioned so that flange portions  102  thereof are located within channel  116  and fixedly connect bushings  106 , inner cowl aft portion  84 , dome inner portion  86  and annular member  114 . 
   It will further be seen that a plurality of circumferentially spaced support members  120  (known as a drag link) are connected to inner support member  34  and extend axially forward to be movably connected with inner liner forward end  82 . In particular,  FIG. 6  shows that each drag link  120  has a wishbone-type shape and includes first and second portions  121  and  123  which extend from a common junction portion  125 . First and second drag link portions  121  and  123  each include an opening  122  and  127  formed in a forward portion  129  and  131 , respectively, thereof which are in alignment with adjacent openings  88 ,  90  and  92  of inner liner forward end  82 , inner cowl aft portion  84  and dome inner portion  86 . In this way, pin members  94  are able to extend therethrough so that first and second portions  121  and  123  of drag link  120  are clamped between pin head portions  96  and bushings  106 . Accordingly, forward portions  129  and  131  are spaced so that at least one pin member  94  of mounting assembly  80  is positioned therebetween. An aft portion  125  of each drag link  120  includes an opening  133  therein so that it may be connected to inner annular support member  34  via a bolt  135  and nut  137 . It will be appreciated that drag links  120  are provided to assist in minimizing vibrations by providing a measure of stiffness to combustor  10 . 
   It will also be seen that inner cowl  26  is also preferably configured in a manner to accommodate mounting assembly  80 . More specifically, inner cowl  26  includes a forward portion  124 , aft portion  84 , and an intermediate portion  126 . Inner cowl aft portion  84  is preferably a flange which is stepped from inner cowl intermediate portion  126  by an amount substantially equivalent to height  112  of bushings  106  as seen by surface  128 . It will also be understood that inner cowl intermediate portion  126  is configured to shield mounting assembly  80 , and specifically bushings  106 , from undesirable air flow entering inner passage  32 . 
   An alternative mounting assembly  130  for an inner liner  132  having an increased thickness  134  at a forward end  136  is depicted in  FIGS. 7-9 . It will be seen that a plurality of circumferentially spaced partial openings  138  are formed therein so as to be aligned with openings (preferably mated slots  155  and  157 ) formed in inner cowl aft portion  84  and dome inner portion  86 . A pin member  140  preferably extends through each set of mated slots  155  and  157  and includes a head portion  142  at a first end thereof which is sized so as to be located within each partial opening  138 . Pin members  140  preferably include threads  144  formed thereon so that a nut  146  is adjustably connected to a second end of each pin member  140  opposite head portion  142 . In this way, inner cowl aft portion  84  and dome inner portion  86  are fixedly connected between nut  146  and pin head portion  142 . Head portion  142  of pin members  140  is then able to slide radially in partial openings  138  as inner cowl aft portion  84  and dome inner portion  86  experience thermal growth greater than inner liner forward end  82 . Of course, a depth  148  of partial opening  138  and a height  150  of head portion  142  are sized so as to accommodate a designated amount of thermal growth for inner cowl aft portion  84  and dome inner portion  86 . It will be appreciated that any type of anti-rotational feature will preferably be utilized with pin member  166 , including one incorporated into the interior of pin head portion  168  instead of just the exterior feature to pin member  166  shown. 
   It will be noted that each nut  146  preferably includes a flange portion  152  extending from an outer surface  154  thereof. Although not shown, it will be appreciated that an annular member having a channel like those identified by reference numerals  68  and  114  and described above may be positioned between nut  146  and dome inner portion  86  to prevent axial and circumferential movement of inner cowl aft portion  84  and dome inner portion  86  with respect to inner liner forward end  82 . 
   It will be seen in  FIG. 9  that a plurality of circumferentially spaced and corresponding slots  155  and  157  are preferably formed in inner cowl aft portion  84  and dome inner portion  86 , respectively, in order to assist in the assembly of inner cowl aft portion  84  and dome inner portion  86  via mounting assembly  80 . Pin members  140  are preferably pre-positioned in partial openings  138 . Thereafter, inner cowl aft portion  84  is moved aft and dome inner portion  86  is moved forward so that each pin member  140  is located therebetween. Nuts  146  are then threaded onto pin members  140  to fixedly connect inner cowl aft portion  84  and inner dome portion  86  between head portions  142  of pin members  140  and nuts  146 . It will also be appreciated that mounting assembly  80  may be utilized with an inner cowl and dome which are segmented circumferentially. 
   A second alternative mounting assembly  156  for an inner liner  158  having a substantially uniform thickness at a forward end  162  is depicted in  FIGS. 10 and 11 . It will be seen that a plurality of circumferentially spaced openings  164  are formed therein so as to be aligned with openings  90  and  92  formed in inner cowl aft portion  84  and dome inner portion  86 . A pin member  166  preferably extends through each set of aligned openings  90  and  92  and includes a head portion  168  at a first end thereof which is sized so as to be radially movable through each opening  164 . Pin members  166  preferably include threads  170  formed thereon so that a nut  172  is adjustably connected to a second end of each pin member  166  opposite head portion  168 . In this way, inner cowl aft portion  84  and dome inner portion  86  are fixedly connected between nut  172  and pin head portion  168 . Head portion  168  of pin members  166  is then able to slide radially through openings  164  as inner cowl aft portion  84  and dome inner portion  86  experience thermal growth greater than inner liner forward end  82 . Of course, a height  173  of head portion  168  is sized so as to accommodate a designated amount of thermal growth for inner cowl aft portion  84  and dome inner portion  86 . 
   It will be noted that each nut  172  preferably includes a flange portion  174  extending from an outer surface  176  thereof. Although not shown, it will be appreciated that an annular member having a channel like those identified by reference numerals  68  and  114  and described above may be positioned between nut  172  and dome inner portion  86  to prevent axial and circumferential movement of inner cowl aft portion  84  and dome inner portion  86  with respect to inner liner forward end  82 . 
   Each of the mounting assemblies described herein reflect a method of mounting outer liner  16  to dome  20  and an outer cowl  24  in a combustor  10 . Since outer liner  16  is made of a material having a lower coefficient of thermal expansion than dome  20  and outer cowl  24 , the method includes a first step of fixedly connecting outer cowl aft portion  38  and dome outer portion  40 . Secondly, outer liner forward end  36  is connected to outer cowl aft portion  38  and dome outer portion  40  in a manner so as to permit radial movement of outer cowl aft portion  38  and dome outer portion  40  with respect to outer liner forward end  36 . An additional step of the method preferably includes connecting outer liner forward end  36  to outer cowl aft portion  38  and dome outer portion  40  in a manner so as to prevent axial movement of outer cowl aft end  38  and dome outer portion  40  with respect to outer liner forward end  36 . A further additional step of the method preferably includes connecting outer liner forward end  36  to outer cowl aft portion  38  and dome outer portion  40  in a manner so as to prevent circumferential movement of outer cowl aft end  38  and dome outer portion  40  with respect to outer liner forward end  36 . Of course, such method steps are equally applicable to inner liner forward end  82 , inner cowl aft portion  84  and dome inner portion  86  in a similar manner. 
   Having shown and described the preferred embodiment of the present invention, further adaptations of the mounting assemblies for a forward end of a combustor liner can be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the invention. In particular, it will be appreciated that mounting assemblies  130  and  156 , while described with respect to an inner liner, may also be utilized with an outer liner having a similar configuration (i.e., increased thickness at a forward end thereof for mounting assembly  130 ) with either partial openings or complete openings formed therein.