Abstract:
An interchangeable combustor chute for directing airflow into a gas turbine engine combustor. In one aspect the combustor chute is secured to the combustor liner by mechanical fastener. The combustor chute is formed of a high temperature resistant material such as ceramics.

Description:
This invention was made with Government support under Contract No. N00019-96-C-0176 awarded by the United States Navy. The Government has certain rights in this invention. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to the design and construction of a gas turbine engine combustor having a high temperature chute for directing airflow into the combustor. More particularly, in one embodiment of the present invention, a combustor chute is secured to the combustor liner by a mechanical retaining ring. Although the present invention was developed for use in a gas turbine engine, certain applications may be outside this field. 
     A long-recognized need by many gas turbine engine designers is to achieve both a greater thermodynamic efficiency and increased power output per unit of engine weight. Currently, increased efficiency and engine performance can be obtained by increasing the operating temperature of the hot working fluid. Theoretically, a gas turbine engine could operate at stoichiometric combustion ratios in order to extract the greatest possible energy from the fuel consumed. However, temperatures at stoichiometric and even non-stoichiometric combustion are generally beyond the endurance capabilities of traditional metallic gas turbine engine components. 
     The hot working fluid in the gas turbine engine results from the combustion of a fuel mixture within a combustor. Air is introduced through an opening in a combustor liner into the combustion chamber to provide the desired fuel mixture. In order to enhance the combustion process, many gas turbine engine designs utilize a metal combustor chute that is welded to the combustor liner to direct the air into the combustor chamber. The welded metal chute design has limited the type of materials used in the combustor chute and does not facilitate replacement of combustor chutes that have been damaged or eroded by the environment. 
     Although the prior technique utilizing a welded metal combustor chute is a step in the right direction, the need for additional improvement still remains. The present invention satisfies this need in a novel and non-obvious way. 
     SUMMARY OF THE INVENTION 
     One form of the present invention contemplates a combustor chute formed of a high temperature resistant material. 
     Another form of the present invention contemplates a combustor chute assembly comprising a replaceable combustor chute and a mechanical fastener. 
     Another form of the present invention contemplates an apparatus, comprising: a mechanical housing; a combustor liner located within and spaced from the housing and having at least one opening therethrough, the combustor liner defining a space adapted for the combustion of a fuel; a member having a first end and a second end and a passageway therethrough adapted for the passage of a fluid into the space for the combustion of fuel, the first end received within the at least one opening and the second end extending into the space; and means for releasably fastening the first end with the liner. 
     Yet another form of the present invention contemplates a combustor for a gas turbine engine comprising: a mechanical housing; a combustor liner located within the housing and defining a combustion chamber adapted for the combustion of a fuel, the combustion liner having at least one opening therein; a passageway formed between the mechanical housing and the combustor liner, the passageway adapted for the passage of a fluid to the at least one opening; at least one combustor chute having a first portion received within the at least one opening and in fluid communication with the passageway and a second portion extending into the combustion chamber; and a removable fastener engaging with the at least one combustor chute to releasably secure the at least one combustor chute with the combustor liner. 
     Also, another form of the present invention contemplates a gas turbine engine combustor chute, comprising: a single piece body member having a first end and a second end with a passageway therethrough, the first end having a fastener-receiving portion adapted to receive a fastener therein and to secure the first end with a combustor liner. 
     Yet another form of the present invention contemplates a method of installing a combustor chute within a gas turbine engine combustor, comprising: positioning the combustor chute within the combustion chamber; inserting one end of the combustor chute into an opening formed in a combustor liner of the combustor; passing at least a portion of the one end of the combustor chute through the combustor liner so that it extends from the liner; and engaging a mechanical fastener with the portion of the combustor chute extending from the combustor liner. 
     One object of the present invention is to provide a unique combustor chute for a gas turbine engine. 
     Related objects and advantages of the present invention will be apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustrative view of a gas turbine engine. 
     FIG. 2 is a sectional view of a combustor comprising a portion of a gas turbine engine. 
     FIG. 3 is an enlarged exploded view of the combustor chute assembly of FIG.  2 . 
     FIG. 4 is perspective view of the combustor chute assembly of FIG. 3 coupled to a combustor liner. 
     FIG. 5 is a cross-sectional view of the combustor chute of FIG. 4 coupled to a combustor liner. 
     FIG. 6 is a cross-sectional view of the combustor chute taken along line  6 — 6  of FIG.  3 . 
     FIG. 7 is an exploded view of an alternate embodiment of a combustor chute assembly coupled to a combustor liner. 
     FIG. 8 is a perspective view of the combustor chute assembly of FIG. 7 coupled to a combustor liner. 
     FIG. 9 is an exploded view of another embodiment of a combustor chute assembly coupled to a combustor liner. 
     FIG. 10 is a perspective view of the combustor chute assembly of FIG. 9 coupled to a combustor liner. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device and/or method, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
     Referring to FIG. 1, there is illustrated a schematic representation of a gas turbine engine  10 , which includes a fan section  12 , a compressor section  14 , a combustor section  16 , and a turbine section  18  that are integrated together to provide an aircraft flight propulsion engine. This type of gas turbine engine is generally referred to as a turbo-fan. One alternate form of a gas turbine engine includes a compressor section, a combustor section and a turbine section that have been integrated together to produce an aircraft flight propulsion engine without the fan section. The term aircraft is generic and includes helicopters, airplanes, missiles, unmanned space devices and any other substantially similar devices. It is important to realize that there are multitudes of ways in which the gas turbine engine components can be linked together. Additional compressors and turbines could be added with intercoolers connecting between the compressors, and reheat combustion chambers could be added between the turbines. The present invention is applicable to all types of gas turbine engines and is not intended to be limited herein to an engine similar to that shown in the schematic. 
     A gas turbine engine is equally suited to be used for an industrial application. Historically, there has been widespread application of industrial gas turbine engines, such as pumping sets for gas and oil transmission lines, electricity generation, and naval propulsion. 
     The compressor section  14  includes a rotor  20  having a plurality of compressor blades  22  coupled thereto. The rotor  20  is affixed to a shaft  24  that is rotatable within the gas turbine engine  10 . A plurality of compressor vanes  26  are positioned within the compressor section  14  to direct the fluid flow relative to blades  22 . Turbine section  18  includes a plurality of turbine blades  28  that are coupled to a rotor disk  30 . The rotor disk  30  is affixed to the shaft  24 , which is rotatable within the gas turbine engine  10 . Energy extracted in the turbine section  18  from the hot gas exiting the combustor section  16  is transmitted through shaft  24  to drive the compressor section  14 . Further, a plurality of turbine vanes  32  are positioned within the turbine section  18  to direct the hot gaseous flow stream exiting the combustor section  16 . 
     The turbine section  18  provides power to a fan shaft  34 , which drives the fan section  12 . The fan section  12  includes a fan  36  having a plurality of fan blades  38 . Air enters the gas turbine engine  10  in the direction of arrows A and passes through the fan section  12  into the compressor section  14  and a bypass duct  40 . 
     Referring to FIG. 2, there is illustrated a partial sectional view of the combustor section  16 . The combustor apparatus  110  comprises a mechanical housing/case  114 , an igniter  113 , an outer combustor liner  112   a,  an inner combustor liner  112   b,  a fueling nozzle (not illustrated) and at least one combustor chute assembly  123 . In the embodiment illustrated herein the outer combustor liner  112   a  and the inner combustor liner  112   b  define an annular combustion chamber  124  that is substantially symmetrical about a centerline Z. However, the present invention is not limited to an annular combustor and is applicable with other combustor apparatus configurations such as but not limited to a single can, multi-can and can-annular. The combustor liners  112   a  and  112   b  are spaced from the mechanical housing/case  114  and a passageway  116  provides for the passage of compressed fluid from the compressor section  14  in the general direction of arrow Y. 
     The combustor liners  112   a  and  112   b  include inner surfaces  126  and  128  respectively that are located within the combustion chamber  124  and are exposed to the hot gases generated during the combustion process. An aperture  118  is formed within at least one of the combustor liners  112   a  and  112   b  for the receipt of the combustor chute  123   a.  The combustor chute  123   a  is received within the aperture  118  and secured to the combustor liner by a mechanical fastener  121 . The present invention contemplates a combustor apparatus having at least one combustor chute  123   a,  and more preferably has a plurality of combustor chutes  123   a.  The position of the individual combustor chutes for a specific design can be determined by techniques such as rig testing and CFD analysis. The combustor chutes  123   a  may be staggered or aligned with fuel nozzles, spray bars, or any other orifice that delivers fuel within a combustor scheme. Axial orientation of the combustor chutes  123   a  may be in a single row or multiple rows, which are either staggered or aligned relative to each other. 
     The combustor chute  123   a  extends into the combustion chamber  124  and is subjected to the hot gases from the combustion process. In a preferred form the combustor chute  123   a  is a unitary member, however an integral combustor chute formed of a plurality of interconnected pieces is also contemplated herein. The combustor chute  123   a  and the combustor liners  112   a  and  112   b  can be formed of the same material or of dissimilar materials. Combustor chute  123   a  is formed of a high temperature resistant material and more preferably the material is suitable for use in an environment where the temperature can be in excess of 3000° Fahrenheit. More preferably, the combustor chute  123   a  is formed of a high temperature metallic material, such as, but not limited to, Hastelloy X or Mar-M247, or an intermetallic material, and most preferably the combustor chute  123   a  is formed of a ceramic material. 
     Referring to FIGS. 3 and 4, there is illustrated an exploded view of the combustor chute assembly  123  proximate a portion of the outer combustor liner  112   a.  In one embodiment the combustor liner has a plurality of cooling holes  130  formed therethrough, however other combustor liners having no cooling holes and/or alternate cooling designs are contemplated herein. Combustor chute assembly  123  includes: combustor chute  123   a  having a first end  131 , an opposite second end  132 , and a passageway  133  therebetween for the passage of a fluid; and the mechanical fastener  121 . First end  131  includes a fastener—receiving portion  134  for receiving and retaining the mechanical fastener  121 . In one embodiment the fastener—receiving portion  134  is disposed between a first portion  135  and second portion  136 . The second portion  136  is sized to fit closely within the aperture  118  within the combustor liner  112   a.  A flange member  140  extends from the chute assembly  123   a  and has a surface  141  adapted for abutting the inner surface  126  or  128  of the respective combustor liner. The flange member  140  stopping further passage of the combustor chute  123   a  into the opening  118 . In one preferred embodiment, first portion  135  includes a first set of lobes  137  and second portion  136  includes a second set of lobes  138 . It is understood herein that the combustor chute assembly  123  can also be coupled with the inner combustor liner  112   b.    
     Mechanical fastener  121  is interengageable with fastener-receiving portion  134  and preferably is a retaining ring that is elastically deformed during placement. More preferably, the retaining ring has a two-turn design so that in the event of a fracture the combustor chute  123   a  will not fall into the combustion chamber. The present invention contemplates other types of mechanical fasteners for removably coupling the combustor chute  123   a  to the combustor liner  112   a,  such as but not limited to snap rings, pins, spring clips, and threaded fasteners. 
     As discussed previously, the combustor liner includes an opening  118  formed therethrough for receipt of the combustor chute  123   a.  The opening  118  extending through the respective combustor liner and has a sidewall surface  139  defining the opening. While opening  118  has been illustrated as a generally lobed-shaped opening, it is understood herein that the opening can be formed in alternative shapes including but not limited to circular, elliptical, polygonal, triangular, square, rectangular, and slots. The sidewall surface  139  is configured to substantially correspond with the outer surface  138   a  of the second set of lobes  138 . 
     In one embodiment the second set of lobes  138  define an anti-rotation portion that engages with the opening  118  to prevent rotation relative to the combustor liner. In one preferred form, the second set of lobes  138  includes at least one lobe and preferably a plurality of lobes. In a more preferred embodiment the second set of lobes comprises three lobed-shaped portions  138   b,    138   c  and  138   d  (not illustrated). The shape of the second set of lobes is selected to correspond with the shape of the opening  118 , and more particularly the sidewall surface  139 . It is understood that the lobe portions  138   b,    138   c  and  138   d  can be replaced by members having other shapes that would occur to those skilled in the art, such as, projections, tabs, ears, and the like, which can define any number of shapes, such as curved, triangular and/or rectangular shaped projections. In a preferred embodiment the first set lobes  137  and the second set of lobes  138  have substantially the same shape. However, in alternate embodiments the two sets of lobes  137  and  138  have different shapes. 
     Referring to FIG. 4, there is illustrated a perspective view of the combustor chute  123   a  coupled to the combustor liner  112   a.  The first end  131  of combustor chute  123   a  is received within the opening  118  and the flange member  140  abuts the inner surface  126  of the combustor liner  112   a.  Further, the fastener-receiving portion  134  is positioned above the surface  142  of the combustor liner  112   a.  The mechanical fastener  121  is positioned within the fastener-receiving portion  134  and extends over a portion of the surface  142  to hold the combustor chute  123   a  against the liner  112   a.    
     Referring to FIG. 5, there is illustrated a cross-sectional view of the combustor chute  123   a  coupled to the combustor liner  112   a.  In one embodiment the combustor chute  123  has a scarf angle θ formed on the second end  132  thereof, and preferably the scarf angle θ is within a range of about 60° to about 120°. In one embodiment, the combustor chute has a scarf angle of about 90°. The scarf angle θ is formed relative to a centerline X. Flange member  140  prevents the passage of the second end  132  of the combustor chute  123   a  into the opening  118 . In the illustrated embodiment the surface  141  defined on the flange member  140  abuts the inner surface  126  of the combustor liner  112   a  and the fastener  121  abuts the outer surface  142  of the combustor liner  112   a.  Further, while fastener  121  is used to mechanically secure the combustor chute  123   a  to the combustor liner  112   a  it can be readily removed to allow for removal of the combustor chute  123   a  for repair and/or replacement. 
     It will be appreciated that the combustor chute  123   a  can be configured so that it may or may not directly contact the combustor liner. Preferably, combustor chute  123   a  is sized to allow for differences in thermal expansions between the combustor liner  112   a  and the combustor chute  123   a  so as to inhibit cracking of the respective components during the heating and cooling cycles. Further, it is understood that a thermally resistive material can be placed between the combustor chute  123   a  and the combustor liner  112   a.    
     With reference to FIG. 6, there is illustrated a sectional view taken along line  6 — 6  of FIG.  3 . In a preferred embodiment the combustor chute  123   a  includes an alignment feature to insure that the combustor chute is oriented in a predetermined manner within the opening  118 . The alignment feature utilizes a geometric relationship that only allows the insertion of the combustor chute  123   a  into the opening  118  in one orientation. In a preferred embodiment the second set of lobes  138   b,    138   c  and  138   d  are configured about the combustor chute  123   a  in a non-equidistant relationship to each other. Thus, the configuration of lobes  138   b,    138   c  and  138   d  are adapted to align the combustor chute  123   a  in a predetermined orientation within the opening  118  of the liner  112   a.  One embodiment of the present invention does not include the alignment feature, and alternate embodiments of the alignment feature include varying structures utilized for affecting the alignment between the combustor chute  123   a  and the combustor liner  112   a.    
     With reference to FIGS. 7 and 8, there is illustrated an alternative embodiment of the combustor chute  123   a  coupled to the combustor liner  112   a.  The combustor chute  123   a  and combustor liner  112   a  are substantially similar to the previously described combustor chutes and liners and like feature numbers will be utilized to represent like features. In one embodiment mechanical fastener  221  is defined by an energizing device that preloads and retains the combustor chute  123   a  against the inner surface  126  of the combustor liner  112   a.  The mechanical fastener  221  is preferably a wave washer having a spring rate that preloads the combustor chute  123   a  against the liner  112   a.  Mechanical fasteners suitable to preload the combustor chute against the combustor liner are believed known to those of ordinary skill in the art. Smalley Steel Ring Co., 385 Gilman Aveneue, Wheeling Ill. is an example of one company that distributes a line of spring retaining rings. 
     With reference to FIGS. 9 and 10, there is illustrated an alternate embodiment of the combustor chute coupled to the combustor liner  112   a.  The combustor chute assembly  323  is substantially similar to the prior combustor chute assemblies and includes an energizing device  221 , a load distributing member  121  and the combustor chute  223   a.  Further, the components are substantially similar to the previously described components and like feature numbers will be utilized to represent like features. The combustor chute  223   a  is preloaded against the surface  126  of the liner  112   a.  In one embodiment the energizing devise is a wave washer having a spring rate that preloads the combustor chute  223   a  against the liner  112   a.  The load distributing member  121  functions to distribute the load applied from the energizing device  121  to the combustor chute  223   a.  Further, the load distributing member is preferably, but not limited to, utilized with a ceramic material combustor chute. 
     A method of installing the removable combustor chute  123   a  will now be set forth with the aid of FIGS. 1-6. The first end  131  of the combustor chute  123   a  is passed into the opening  118  within the combustion chamber  124 . The first end  131  is passed into the opening  118  to align the second set of lobes  138  within the opening and cause the flange member  140  to be brought into an abutting relation with the inner surface of the combustor liner. Fastener  121  is then engaged within the fastener-receiving portion  134  to releasably secure the combustor chute  123   a  to the combustor liner  112 . The combustor chute  123   a  can be removed by substantially reversing the above described installation procedure. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is considered to be illustrative and not restrictive in character, it is understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.