Abstract:
A variable area air system means for air blast type fuel nozzles for use in gas turbine engines wherein fuel/air ratios are controlled for the purpose of controlling engine emission products to meet mandated emission standards over a wide range of engine operating conditions. The variable area air metering means is connected with a pressure responsive actuating means for controlling the air flow in single fuel system and dual fuel system air blast type fuel nozzle and support assemblies used in gas turbine engines.

Description:
This application is a continuation of application Ser. No. 212,281, filed 12-2-80, now abandoned. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to a variable area means for air systems of air blast type fuel nozzle. The variable area means is intended for use in the air systems of single fuel system and dual fuel system air blast type fuel nozzle assemblies for use in variable geometry (area) combustion systems of advanced design gas turbine engines. The purpose of controlling fuel/air ratios is to meet emission standards over a wide range of engine operating conditions. 
     Present technology for accomplishing movement of variable area air systems of nozzles and combustors has been through the use of elaborate mechanical linkage systems with imput means through the engine case, such as disclosed in U.S. Pat. No. 3,905,192. U.S. Pat. No. 4,044,533 issued Aug. 30, 1977 to Vaught discloses a variable geometry swirler in a combustion nozzle of a fuel system. 
     It is an object of this invention to provide a variable area air metering means connected with a pressure responsive actuating means integral within a nozzle assembly for controlling the air flow in the air systems of single fuel system and dual fuel system air blast type fuel nozzle and support assemblies used in gas turbine engines. A further object of the invention is to provide a passage for a pressurized actuating means, either liquid or gas, through the nozzle and support assembly to the inside of the engine case for the purpose of operating the variable area air system of the nozzle and combustor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a typical external view of an air blast type fuel nozzle and support assembly with a variable area air system means in the combustion system of a gas turbine engine. 
     FIG. 2 shows a detail cross-sectional view of a dual fuel system air blast fuel nozzle assembly with a variable area air system means for controlling air flow to both inner and outer air systems of a typical dual fuel system air blast type fuel nozzle assembly. 
     FIG. 3 shows a modification of the nozzle assembly and variable area air system means as shown in FIG. 2 for controlling air flow to the outer air system of applicants&#39; dual system air blast type fuel nozzle assembly. 
     FIG. 4 shows a further modification of the nozzle assembly and variable area air system means as shown in FIG. 2 for controlling air flow to the inner air system of applicants&#39; dual fuel system air blast type fuel nozzle assembly. 
     FIG. 5 shows a detail cross-sectional view of a single fuel system air blast type fuel nozzle assembly with a variable area air system means for controlling air flow to both inner and outer air systems of a typical single fuel system air blast type fuel nozzle assembly. 
     FIG. 6 shows a further modification of the nozzle assembly and variable area air system means as shown for controlling air flow to the outer air system of applicant&#39;s single fuel system air blast type fuel nozzle assembly. 
     FIG. 7 shows a modification of the nozzle assembly and variable area air system means as shown in FIG. 5 for controlling air flow to the inner air system of applicant&#39;s single fuel system air blast type fuel nozzle assembly. 
     FIG. 8 shows a detail cross-sectional view of a dual fuel system air blast fuel nozzle assembly with a variable area air system means for controlling air flow to both inner and outer air systems of a typical fuel system air blast fuel nozzle assembly with the integral pressure responsive actuating means connected to the primary nozzle fuel passage. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the fuel feeding system for the invention disclosed is most particularly adapted for gas turbine engines as indicated by the fragmentary representation thereon. In such engines, air is compressed by compressor and is discharged through an opening 10. A portion of the air enters a combustion chamber 12 for ignition with fuel discharged from nozzles 14. The remainder of the air passes on opposite sides of the combustion chamber 12 through passage 16 defined by the outer engine case 18 and an inner engine case 20 not shown. The products of combustion are discharged from the combustion chamber 12 on to a turbine (not shown) in a known fashion to drive the compressor and to generate a power output such as a propulsive jet force. 
     The amount of fuel supplied to the nozzle 14 varies for different engine operating conditions. Pressurized fuel is supplied to the nozzle 14 through the support assembly 22 by means of the primary nozzle fuel inlet fitting 24, and the secondary nozzle fuel inlet fitting 26. A primary nozzle fuel passage 28 provides pressurized fuel to the primary fuel system. A secondary nozzle fuel passage 30 provides pressurized fuel to the secondary fuel system. The variable area air system actuating means 32, using either liquid or gas, comprises an inlet fitting 34 and passage 36 to the interior of nozzle 14 in a manner to be herein described. 
     It is apparent as shown in FIG. 1, the nozzle and support is a unitary assembly and mounted to the outer engine casing 18 by bolts 38, with a typical prechamber 40 at the end of nozzle 14 mounted within an opening 42 of the combustion chamber 12. An engine spark igniter 44 is mounted to the outer engine case 18 and extends through the combustion chamber liner wall 19 to provide ignition in the combustion chamber 12 to the combustible mixture emanating from the nozzle 14. 
     Referring to FIG. 2, the passages 28, 30 and 36 through the nozzle support 22 are shown in broken cross-section view of the nozzle 14. 
     The nozzle support 22 is fabricated to the nozzle adaptor or housing 48 by means of brazing rings 50, and the nozzle adaptor 48 is fabricated to the prechamber 40 by brazing ring 52, in a manner to be described hereinafter. 
     The nozzle adaptor 48 comprises the main body section of the nozzle 14 in that it includes passages 28&#39;, 30&#39; and 36&#39; which join the passages 28, 30 and 36 in the nozzle support 22. 
     The primary nozzle fuel passages 28, 28&#39; extend into a chamber 54, which includes a primary nozzle fuel filter 56. Primary fuel is thus adapted to flow into the primary nozzle means 55 through the fuel filter 56 into a recess 58, through slots 60 of the primary nozzle swirler 62, through recessed area 64 and through the primary nozzle swirl holes 66 into the primary nozzle swirl chamber 68. The primary fuel is discharged through the primary nozzle orifice 70 of the primary nozzle swirl chamber in a hollow cone spray out of the primary nozzle orifice 70. 
     Around the exit portion of the primary nozzle an air shroud 72 is welded at 74 to the primary nozzle body 76. The primary nozzle body 76 has passages 78 to supply air from the inner air system under the air shroud 72 and washes across the nozzle face to prevent carbon formations on the face of the nozzle. 
     The secondary nozzle fuel passages 30, 30&#39; extend into an area 90 and is adapted to provide fuel flow through angled secondary swirl slots 92, through area 94, past slots 95 of secondary nozzle swirler 96 and exits through annulus 98. 
     The outer air system 100 is adapted to exit through outer air swirl vanes or helical slots 101 to prechamber area 41 while the inner air system 102 is adopted to exit through the inner air swirl vanes 103 to prechamber area 41 via chamber 104. The actuating means to control the metering for the outer and inner air systems 100 and 102, respectively comprises, either air, gas, or liquid, through the passages 36 and 36&#39; to control metering of the air to the outer and inner air systems. For example, air is adopted to enter the bore 105 and is adapted to move the piston 107 against the bias of spring 109. That is, the piston 107 is a spring biased pressure responsive valve means. The piston 107 is slidable in the actuating piston sleeve 111 that is fabricated by means of brazing ring 113 to the rear portion of the housing or nozzle adaptor 48. A spring retainer 115 holds the concentricity of the spring in the piston sleeve 111 with a snap ring 117 mounted in recess 119 of the sleeve 111 to hold the actuating piston 107 and spring 109 within the sleeve 111. 
     The piston is biased against the spring and moves against it. The piston face comprises an effective area, with an operating pressure flowing through the passages 36, 36&#39; operating against the piston 107 which in turn moves two valves which are attached to the piston rod 121. That is, both outer and inner air systems are controlled by the movement of the piston 107. The outer air system metering valve 123 is mounted on to the end 125 of the piston rod 121 and held in place by a retaining ring 127 secured in a recessed portion 129 of the piston rod end 125. The outer air system metering valve 123 and the inner air system metering valve 141 is adapted to move axially or longitudinally as indicated by arrow 131. The opening 133 is adapted to be opened to allow more air to enter the outer air system chamber 135. That is, the outer air system 100 is adapted to flow through the opening 133 through the chamber 135, which is between the body of the nozzle adaptor 48 and the member 137, and is adapted to flow past the outer air swirl vanes 101 to exit into the prechamber area 41. The member 137 separates the outer air system 100 from the inner air system 102. Simultaneous with the movement of air through the outer air system, the inner air system air metering valve 141 is adapted to move to allow air to enter the inner air system chamber 155 via openings 143 in the closed end portion 145 of the outer air system air metering valve 123 and through the opening 149 that exists between the inner air system air metering valve 141 and the end of the outer air system air metering valve sleeve 151. The inner air system 102 thus is adapted to flow through the openings 143 of the outer air system air metering valve 123, past the opening 149 through chambers 153 and 155, past the inner air swirl vanes 103 on the primary nozzle body and through chamber 104 to exit into the prechamber area 41 through annulus 156. An air scoop 157 is fabricated to the air metering valve 123 by means of brazing ring 159 in a manner to be described hereinafter. 
     It is thus apparent that in the dual fuel system air blast type nozzle having a variable area air system actuating means that the piston is adapted to move both valves; that is, the outer air system air metering valve 123 and the inner air system air metering valve 141 is moved to control the ratio of air in relation to the fuel in the nozzle. 
     The nozzle and support is a unitary structure in that all the parts are fitted together and brazing rings are placed within the annular recesses of the various members and the completely assembled unit is then placed in a furnace. The elevated temperature in the furnace melts the brazing rods, such as shown in FIG. 2 namely, 50, 113, 161, 162, 163, and 167, to the mating members to form a unitary assembly. A brazing method similar to the method disclosed herein is disclosed in U.S. Pat. No. 3,827,638 issued Aug. 6, 1974 and U.S. Pat. No. 3,871,063 issued Mar. 18, 1975 to Robert M. Halvorsen. 
     BRIEF DESCRIPTION OF THE MODIFICATIONS 
     FIG. 3 shows a modification of the nozzle assembly showing essentially the same elements as in FIG. 2, with the exception of the inner air system air metering valve. That is, movement of the piston 307 longitudinally along the direction of arrow 331 moves the piston rod 325. The outer air metering valve 323 is attached to the end of the piston rod 325 by a retaining ring 327 which is secured thereto in annular recess 329. It is thus apparent that as the pressure in the variable air system actuating means increases, the piston moves axially to allow more air to enter the outer air system 300 through the opening 333, while the inner air system 302 has a constant flow of air through the open vent means 343 of the closed end portion 345 of air metering valve 323. 
     FIG. 4 shows a further modification of the nozzle assembly showing a pressure responsive variable area metering means for controlling air flow to the inner air system of a dual fuel system air blast type fuel nozzle assembly. That is, the outer air metering valve is removed and only the inner air system air metering valve is adapted to be moved longitudinally along the direction of arrow 431. As the pressure in the variable area air system actuating means increases, the piston 407 moves axially, moving the inner air system air metering valve 441, allowing more air to enter the inner air system 402 through the opening 449. The air metering valve 441 is connected to the end portion 425 of piston rod 421 by means of a retaining ring 427 sitting in recess 429 of the piston rod. It is apparent that the outer air system 400 is adapted to flow through the chamber 435 of nozzle adaptor 448 without hindrance at a constant flow. 
     FIG. 5 shows another modification of the nozzle assembly showing a pressure responsive variable area air metering means for controlling air flow to both inner and outer air systems of a typical single fuel system air blast type fuel nozzle assembly. This is evident by the view of FIG. 5 in cross-section showing the deletion of the primary nozzle system, and showing instead a nozzle 514 and support assembly 522 with the fuel passages 530 and 530&#39; adapted to supply fuel to chamber 590, through angled swirl slots 592, through area 594, past slots 595 of nozzle swirler 596 to exit through annulus 598. Piston 507 is adapted to move longitudinally in the direction of arrow 531 when pressurized through passages 536 and 536&#39; to move both inner air metering valve 541 and outer air metering valve 523 and allow more air to flow through openings 549 and 533 of the inner and outer air systems 500 and 502 respectively. The inner air system 502 flows through chambers 553, 555, past the inner air swirl vanes 503 through chamber 504 and exits into the prechamber area through annulus 556. The annulus 556 is an opening formed between the core 571 and the orifice of nozzle swirler 596. 
     FIG. 6 is a further modification of the nozzle assembly showing a pressure responsive variable area air metering means for controlling air flow to the outer air system of a typical single fuel system air blast type fuel nozzle assembly. The single nozzle fuel system shown in FIG. 5 is modified to include the outer air system 600 which is adapted to be moved longitudinally along the direction of arrow 631 by piston 607. The actuating means to control the movement of the metering valve 623 for the outer air system is adapted to flow through passage 636 and 636&#39; into piston chamber 605 to move piston 607. Movement of piston 607 will effect movement of the outer air metering valve 623 allowing more air to enter through opening 633. The outer air metering valve 623 is connected to the end portion 625 of piston rod 621 by a retaining ring 627. The inner air flow 602 is adapted to be constant. 
     FIG. 7 shows a further modification of the nozzle assembly showing a pressure responsive variable area air metering means for controlling air flow to the inner air system of a typical single fuel system air blast type fuel nozzle assembly. The single system air blast type fuel nozzle shown in FIG. 5 is modified to include the inner air system 702 adapted to flow through opening 749 when the inner air metering valve 741 is moved longitudinally in the direction of arrow 731. The piston 707 is adapted to be moved axially in the piston sleeve 711 by an increase of a pressure medium flowing through passages 730 and 730&#39; into piston chamber 705. The inner air metering valve 741 is connected to the end portion 725 of piston rod 721 by a retaining ring 727. It is thus apparent that the outer air flow 700 remains constant while the inner air flow 702 is variable. 
     FIG. 8 is a modification of the nozzle assembly shown in FIG. 2, showing a pressure responsive variable area air metering means for controlling outer and inner air flow as a function of the fuel pressure. That is, by increasing the supply of fuel through the primary nozzle passages 828 and 828&#39; to the chamber 854, the fluid is divided between the piston area chamber 805 and the primary nozzle exit orifice 870 of the primary nozzle means 855. Thus, increasing the fuel pressure in chamber 805 is adapted to move the piston 807 in the direction of arrow 831 and thus simultaneously move the outer air metering valve 823 and the inner air metering valve 841. Movement of the outer and inner air metering valves 823 and 841, allows more air to flow through openings 833 and 849, in the outer and inner air flow systems 800 and 802, respectively. 
     While the best mode for practicing the invention has been described in detail, and other modes have been described generally in detail, those familiar with the art will recognize various alternative designs and embodiments for practicing the invention as defined by the claims: