Variations in dilution hole design for combustor liners

Abstract

A combustor for a turbine engine includes a combustion chamber, a liner forming a boundary of the combustion chamber, and a plurality of dilution holes extending through the liner to allow airflow into the combustion chamber. The dilution holes include converging dilution holes having a converging cross-sectional profile and diverging dilution holes having a diverging cross-sectional profile.

Description

Technical Field

[0001] The present disclosure relates to a turbine engine including a combustor. Background Art

[0002] The combustor in a turbine engine receives a mixture of fuel and highly compressed air, which is ignited to produce hot combustion gases. These hot gases are used to provide torque in the turbine to provide mechanical power and thrust. Combustor performance is critical to the overall performance of a gas turbine engine and is related to fuel efficiency and reduced nitrogen oxide (NOx) emissions. The continuous demand for improved engine performance (e.g., higher cycle pressure ratio) and fuel efficiency (e.g., lower specific fuel consumption) poses a conflicting challenge with the economic requirement to meet environmental requirements for NOx emissions and longer combustor component life cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Features and advantages of the present disclosure will be apparent from the following description of various exemplary embodiments, as illustrated in the drawings, in which like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements.

[0004] Figure 1 An example of a turbine engine according to an embodiment of the present disclosure is shown.

[0005] Figure 2 Shown along Figure 1 Schematic cross-sectional view of the turbine engine shown in FIG. 1 taken along line 2 - 2 .

[0006] Figure 3 Shown along Figure 2 3 is a perspective cross-sectional view of a combustor of a turbine engine shown in FIG. 1 taken along line 3 - 3 .

[0007] Figure 4 Shown along Figure 3 Schematic cross-sectional view of the combustion chamber of the burner shown in FIG. 4 , taken along line 4 - 4 .

[0008] Figure 5A A view is provided from the cold side of the liner of the combustion chamber to the hot side of the liner toward the centerline axis.

[0009] Figure 5B Shown is a view taken along line 5B-5B from a position behind the combustion chamber looking forward. Figure 5A Cross section of the dilution hole in .

[0010] Figure 6 The effects of varying diverging and converging dilution holes on the fuel-air mixing zone are conceptually illustrated.

[0011] Figure 7AAn embodiment of varying dilution holes is shown, providing a view from the cold side of the liner of the combustor to the hot side of the liner toward the centerline axis.

[0012] Figure 7B Shown is a view taken along line 7B-7B. Figure 7A A cross-section of the dilution holes in the engine provides a view looking forward from a position behind the combustion chamber.

[0013] Figure 8A Another embodiment of a varying dilution hole is shown, providing a view from the cold side of the liner to the hot side of the liner toward the centerline axis of the combustor.

[0014] Figure 8B Shown is a view taken along line 8B-8B. Figure 8A A cross-section of the dilution holes in the engine provides a view looking forward from a position behind the combustion chamber.

[0015] Figure 9A Yet another embodiment of a varying dilution hole is shown, providing a view from the cold side of the liner of the combustor to the hot side of the liner toward the centerline axis.

[0016] Figure 9B Shown is a view taken along line 9B-9B. Figure 9A A cross-section of the dilution holes in the engine provides a view looking forward from a position behind the combustion chamber.

[0017] Figure 10A Another embodiment of a varying dilution hole is shown, providing a view from the cold side of the liner to the hot side of the liner toward the centerline axis of the combustor.

[0018] Figure 10B Shown is a section taken along line 10B-10B Figure 10A A cross-section of the dilution holes in the engine provides a view looking forward from a position behind the combustion chamber.

[0019] Figure 11A Yet another embodiment of a varying dilution hole is shown, providing a view from the cold side of the liner of the combustor to the hot side of the liner toward the centerline axis.

[0020] Figure 11B Shown is a view taken along line 11B-11B Figure 11A A cross-section of the dilution holes in the engine provides a view looking forward from a position behind the combustion chamber. DETAILED DESCRIPTION

[0021] The features, advantages and embodiments of the present disclosure are set forth or apparent through consideration of the following detailed description, drawings and claims. In addition, it should be understood that the following detailed description is exemplary and intended to provide further explanation, rather than limiting the scope of the present disclosure as claimed.

[0022] Various embodiments are discussed in detail below. Although specific embodiments are discussed, this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure.

[0023] As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of each component.

[0024] The terms "front" (or "forward") and "rear" refer to relative positions within a turbine engine or vehicle and refer to the normal operating attitude of the turbine engine or vehicle. For example, for a gas turbine engine, front (or forward) refers to a position closer to the engine inlet, while rear refers to a position closer to the engine nozzle or exhaust.

[0025] The terms "outer" and "inner" refer to relative positions within a turbine engine relative to the centerline axis of the engine. For example, outer refers to a position further away from the centerline axis, while inner refers to a position closer to the centerline axis.

[0026] Unless stated otherwise, the terms "coupled," "fixed," "attached," and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0027] One or more components of the turbine engine described below may be manufactured or formed using any suitable process, such as an additive manufacturing process, such as a three-dimensional (3D) printing process. The use of such a process may allow such components to be integrally formed as a single, unitary component, or formed into any suitable number of subcomponents. In particular, the additive manufacturing process may allow such components to be integrally formed and include a variety of features that are not possible using existing manufacturing methods. For example, the additive manufacturing methods described herein are capable of manufacturing combustors having unique features, configurations, thicknesses, materials, densities, passages, manifolds, and mounting structures that are not possible or practical using existing manufacturing methods. Some of these features are described herein.

[0028] The present disclosure and various embodiments relate to turbomachine engines, also known as gas turbine engines, turboprop engines, or turbines. These turbomachine engines can be applied to a variety of technologies and industries. Various embodiments may be described herein in the context of aerospace engines and aircraft machinery.

[0029] In some cases, the turbine engine is configured as a direct drive engine. In other cases, the turbine engine can be configured as a geared engine with a gearbox. In some cases, the propeller of the turbine engine can be a fan encapsulated in a fan casing and / or a nacelle. This type of turbine engine can be referred to as a "ducted engine". In other cases, the propeller of the turbine engine can be exposed (e.g., not in a fan casing or nacelle). This type of turbine engine can be referred to as an "open rotor engine" or a "non-ducted engine."

[0030] Figure 1 An example of a turbomachine engine 100 according to an embodiment of the present disclosure is shown. Types of such engines include turboprops, turbofans, turbines, and turbojets. The turbomachine engine 100 is a ducted engine covered by a protective shroud 105, so the only visible component in this external view is the fan assembly 110. Figure 1 A nozzle, not visible in FIG, also protrudes from the rear end of the turbine engine 100 , beyond the protective shroud 105 .

[0031] Figure 2 Shown along Figure 1 2 is a schematic cross-sectional view taken along line 2-2 of a turbine engine 100 shown in , which may incorporate one or more embodiments of the present disclosure. In this example, the turbine engine 100 is a dual-spool turbine that includes a high-speed system and a low-speed system, both of which are completely covered by a protective cover 105. The low-speed system of the turbine engine 100 includes a fan assembly 110, a low-pressure compressor 210 (also known as a supercharger), and a low-pressure turbine 215, all of which are coupled to low-pressure shafts 217, 218 that extend between the low-speed system components along a centerline axis 220 of the turbine engine 100. The low-pressure shafts 217, 218 enable the fan assembly 110, the low-pressure compressor 210, and the low-pressure turbine 215 to rotate in unison about the centerline axis 220.

[0032] The high-speed system of the turbine engine 100 includes a high-pressure compressor 225, a combustor 230, and a high-pressure turbine 235, all of which are coupled to a high-pressure shaft 237 that extends between the high-speed system components along the centerline axis 220 of the turbine engine 100. The high-pressure shaft 237 enables the high-pressure compressor 225 and the high-pressure turbine 235 to rotate in unison about the centerline axis 220 at a different rotational speed than the rotation of the low-pressure components (and, in some embodiments, at a higher rotational speed and / or in an opposite rotational direction relative to the low-pressure system).

[0033] The components of the low-pressure system and the high-pressure system are positioned so that a portion of the air drawn into turbine engine 100 flows through turbine engine 100 from front to rear through fan assembly 110, low-pressure compressor 210, high-pressure compressor 225, combustor 230, high-pressure turbine 235, and low-pressure turbine 215. Another portion of the air drawn into turbine engine 100 bypasses the low-pressure system and the high-pressure system and flows from front to rear as indicated by arrow 240.

[0034] The combustor 230 is located between the high pressure compressor 225 and the high pressure turbine 235. The combustor 230 may include a fuel cell for receiving fuel from a fuel system ( Figure 2 The mixture is one or more configurations of a mixture of fuel (not shown) and air from the high pressure compressor 225. The mixture is ignited by the ignition system ( Figure 2 The combustion gases (not shown) are ignited to produce hot combustion gases that flow from front to back through the high-pressure turbine 235, which provides torque to rotate the high-pressure shaft 237, thereby rotating the high-pressure compressor 225. After leaving the high-pressure turbine, the combustion gases continue to flow from front to back through the low-pressure turbine 215, which provides torque to rotate the low-pressure shafts 217, 218, thereby rotating the low-pressure compressor 210 and the fan assembly 110.

[0035] In other words, the front stages of the turbine engine 100 (i.e., the fan assembly 110, the low-pressure compressor 210, and the high-pressure compressor 225) are all preparing the intake air for ignition. The front stages all require power to rotate. The rear stages of the turbine engine 100 (i.e., the combustor 230, the high-pressure turbine 235, and the low-pressure turbine 215) provide the necessary power by igniting the compressed air and using the resulting hot combustion gases to rotate the low-pressure shafts 217, 218 and the high-pressure shaft 237 (also known as the rotor). In this way, the rear stages use air to physically drive the front stages, and the front stages are driven to provide air to the rear stages.

[0036] As the exhaust gas leaves the rear end of the rear stage, it reaches the nozzle ( Figure 2 When the exhaust gas passes through the nozzle and combines with the bypass air also driven by the fan assembly 110, an exhaust force is generated, which is the thrust generated by the turbine engine 100.

[0037] Figure 3 Shown along Figure 2 3 . A perspective cross-sectional view of a combustor 230 of a turbine engine 100 is shown taken along line 3-3. The combustor 230 has axial symmetry about a centerline axis 220 defining an axial direction. The combustor 230 also has an annular ring of fuel nozzles 305 spaced circumferentially (also referred to as the circumferential direction) and facing in an aft direction.

[0038] Compressed air 310 from the front stage of the turbine engine 100 flows into the combustor and mixes with fuel from the fuel nozzles 305 in the combustion chamber 315. Each fuel nozzle 305 delivers fuel to a separate area (referred to as the cup) of the total annular volume of the combustion chamber 315. Air enters the combustion chamber 315 from a swirler 317 surrounding each fuel nozzle 305 and through dilution holes 318 in the inner and outer surfaces (also referred to as the liner) of the combustion chamber 315. The fuel-air mixture is ignited in the combustion chamber 315 to produce a steady stream of combustion gases 320, which enters the turbine in the rear stage.

[0039] Figure 4 Shown along Figure 3 Schematic cross-sectional view of the combustion chamber 315 of the combustor 230 shown in FIG. This view shows a cross-sectional view through the mid-plane of a single cup along the axial length. The combustion chamber 315 is centered about the centerline axis 220 ( Figure 4 The annular open space (not shown) of the swirler 317 is defined at the front end by a dome 405 which supports and positions the fuel nozzles 305 and an outer liner 410 and an inner liner 415 on the outer annular surface and the inner annular surface, respectively. The outer liner 410 and the inner liner 415 are coaxial cylinders about the centerline axis 220, with the outer liner 410 and the inner liner 415 spaced radially outward. The dome 405 is oriented perpendicular to the axis of the swirler 317 and is symmetrical about the centerline axis 220, with circumferentially spaced orifices to receive each fuel nozzle 305. Due to its proximity to the combustion chamber, the hot gases and the extreme temperatures generated therein, the dome 405 must be constructed to withstand the harsh environment. The combustion chamber 315 opens in a rearward direction to allow the combustion gases to flow to the high pressure turbine 235 ( Figure 4 not shown).

[0040] The outer liner 410 and the inner liner 415 have a central axis 220 ( Figure 4 The outer liner 410 and the inner liner 415 are both extended in the rear direction along the centerline axis 220 and have dilution holes along their surfaces to allow the high pressure compressor 225 ( Figure 4 Additional air (not shown) is mixed with the fuel in the combustion chamber 315. Each liner has a cold side, which is the surface outside the combustion chamber 315 through which air enters the dilution holes, and a hot side, which is the surface inside the combustion chamber through which air exits the dilution holes.

[0041] exist Figure 4In the example shown, dome 405, outer liner 410, and inner liner 415 are all made of metal, but in some embodiments, at least some portions of outer liner 410 and inner liner 415 may instead be made of a ceramic matrix composite material. According to one embodiment, the liner may include integrally joined portions that are mechanically joined using overlapping portions. In other embodiments, the liner is formed as a single unit in an additive manufacturing process.

[0042] The dome 405 and the outer liner 410 are coupled together at an outer wall 417 of the dome 405, and the dome 405 and the inner liner 415 are coupled together at an inner wall 418 of the dome 405 by fastener arrays 420, 425. The fasteners in the arrays 420, 425 may include one or more of pins, bolts, nuts, nut plates, screws, and any other suitable type of fastener. The arrays 420, 425 are also used to couple the dome 405, the outer liner 410, and the inner liner 415 to a support structure 430 of the combustor 230.

[0043] The support structure 430 defines an inlet 435 for compressed air from the high pressure compressor 225 ( Figure 4 The air flows from front to back as shown by arrow 440 and enters the combustion chamber 315 through the swirler 317 positioned around the fuel nozzle 305. The air also flows into the combustion chamber 315 through the dilution holes in the outer liner 410 (e.g., along arrow 445) and the dilution holes in the inner liner 415 (e.g., along arrow 447). In addition, one or more heat shields and / or guide plates ( Figure 4 A flame retardant (not shown) may also be provided on dome 405 to help protect dome 405 from the heat of the combustion gases.

[0044] Additionally, support structure 430 supports dome 405 with mounting arms 455 connected to structural mounts 450 having annular symmetry about centerline axis 220, forming rearwardly facing channels to receive dome 405, and having forwardly facing apertures to receive fuel nozzles 305. Structural mounts 450 are coupled directly to outer wall 417 and inner wall 418 of dome 405 via fastener arrays 420, 425.

[0045] Figure 5A and 5B Shown Figure 4 A general example of dilution holes 501 , 502 , 503 in a liner 505 of a combustion chamber 315 . Figure 5A Provided towards the centerline axis 220 ( Figure 5A ) from the cold side 507 of the liner 505 (see Figure 5B ) (outside the combustion chamber 315) to the hot side 508 of the liner 505 (see Figure 5B ) (view inside combustion chamber 315). Figure 5BShown is a view taken along line 5B-5B. Figure 5A The cross section of the dilution holes 501, 502, 503 in Figure 4 The rear view (ALF) of the combustion chamber 315. The liner 505 may be Figure 4 The outer liner 410 or the inner liner 415. The dilution holes 501, 502, 503 are shown along Figure 4 The dilution holes are arranged in the circumferential direction of the burner 230 , and additional dilution holes (not shown) may also be arranged in the axial direction of the burner 230 .

[0046] From Figure 2 Air from the high pressure compressor 225 flows in an axial direction (indicated by arrow 510) along the cold side of the liner 505, enters the dilution holes 501, 502, 503 on the cold side 507 of the liner 505 in a lateral direction (indicated by arrow 511), and exits on the hot side 508 of the liner 505 into the combustion chamber 315.

[0047] In some embodiments, the dilution holes 501, 502, 503 are holes machined or drilled through the surface of the liner 505. In other embodiments, the dilution holes 501, 502, 503 are inserts made of metal, for example using additive manufacturing techniques, that are manufactured separately from the liner 505 and are inserted into pre-existing holes. The inserts can be brazed, threaded, press-fitted, or tack-welded into the pre-existing holes.

[0048] In some embodiments, the insert can have cold chutes extending outward from the cold side 507, hot chutes extending outward from the hot side 508 (i.e., into the combustion chamber 315), or both. For example, the dilution holes 501, 502, 503 are inserts having cold chutes 516, 517, 518 and hot chutes 521, 522, 523. In this example, the dilution holes 501, 502, 503 have circular orifices of the same diameter on both the cold side 507 and the hot side 508 of the liner 505. Thus, the dilution holes 501, 502, 503 have a rectangular profile. Alternatively, in some embodiments, one or more chutes on both sides of the liner 505 can be formed integrally with the liner 505 using manufacturing techniques (such as additive manufacturing) rather than as an insert.

[0049] Some embodiments improve the mixing of fuel and air in the combustion chamber 315 by using varying dilution hole profiles. For example, the varying dilution hole profiles can include diverging dilution holes and converging dilution holes, as described in further detail below. Converging dilution holes improve the penetration of air into the combustion chamber 315, which improves the mixing of fuel and air. Diverging dilution holes improve the lateral diffusion of air within the combustion chamber 315, which increases the surface area of ​​the mixing plane. In some embodiments, the dilution holes are designed such that the mass flow rate remains the same even though the profiles of the diverging and converging dilution holes vary.

[0050] Converging and diverging dilution holes have an inlet orifice on the cold side of the liner and an outlet orifice on the hot side of the liner. Converging dilution holes are typically characterized by having an outlet orifice with a transverse cross-sectional area that is smaller than the transverse cross-sectional area of ​​the inlet orifice. Diverging dilution holes are typically characterized by having an outlet orifice with a transverse cross-sectional area that is greater than (or in some cases equal to) the transverse cross-sectional area of ​​the inlet orifice.

[0051] Figure 6 Conceptual illustration of varying diverging and converging dilution holes. Figure 4 6. The effect of the fuel-air mixing zone within the combustion chamber 315 is shown. The view is from a position behind the combustion chamber 315 looking forward, with the circumferential direction indicated by the double-headed arrow 601. Portions of the outer liner 610 and the inner liner 615 are shown, with converging dilution holes 616, 617, 618, 619 and diverging dilution holes 620 and 621 visible and arranged in a staggered, alternating pattern in the two liners.

[0052] Air entering the combustion chamber 315 through converging dilution holes 616-619 creates low-pressure regions 626, 627, 628, and 629 near the corresponding exit orifices on the hot sides of the outer and inner liners 610 and 615. This occurs because the exit orifices are narrower than the inlet orifices on the cold side, causing the air to have a higher velocity upon exiting the orifices. The potential energy from the air pressure is converted into kinetic energy, resulting in a decrease in pressure and an increase in velocity. Conversely, air entering the combustion chamber 315 through diverging dilution holes 620 and 621 creates relatively high-pressure regions 630 and 631 near the corresponding exit orifices on the hot sides of the outer and inner liners 610 and 615.

[0053] The pressure differential created in the circumferential direction by the alternating arrangement of converging and diverging dilution holes causes a central recirculation zone 635 (also referred to as a bubble) of the hot recirculated gas within the combustion chamber 315 to stretch toward the low-pressure regions 626 to 629 and deflect away from the high-pressure regions 630, 631. These stretching and deflecting effects increase shear within the air flow and increase strain in the combustion flame, which increases the turbulent kinetic energy within the recirculation zone 635, thereby improving the mixing of the fuel and air.

[0054] Additionally, the higher penetration and higher diffusion staggered arrangement helps prevent hot gases from accumulating in the dilution wake region, which improves fuel efficiency and shortens the fuel-air mixing zone within the combustor 230. Some advantages of these improvements include reduced NOx emissions and shorter combustor length.

[0055] exist Figure 6 , one possible placement pattern of dilution holes is shown, with diverging dilution holes 620, 621 alternating with converging dilution holes 616, 617, 618, 619 in the outer liner 610 and inner liner 615 of the combustor. However, in different embodiments, many other patterns are possible, including random variations between converging and diverging dilution holes, and repeating groups of each type of dilution hole. For example, one possible pattern is two converging dilution holes followed by two diverging dilution holes. Other possible patterns include three converging dilution holes followed by one diverging dilution hole, or three diverging dilution holes followed by one converging dilution hole. The pattern can be repeated circumferentially, and can be repeated within each cup sector, and can have different patterns at the boundaries between cup sectors. Alternatively, the pattern can be repeated independently of the cup sector.

[0056] In some embodiments, the pattern also includes dilution holes of constant area (i.e., dilution holes that are not converging or diverging, but rather have a constant area). For example, one possible pattern may have converging dilution holes, followed by constant dilution holes, followed by diverging dilution holes, and then repeat. However, the pattern is not limited to a single type of dilution hole per dilution hole. Any number of constant, converging, and diverging dilution holes may be used in any repeating pattern, with the number of each type of dilution hole being different or the same. Furthermore, the pattern may be arranged circumferentially on the liner about the centerline axis 220, axially on the liner along the centerline axis 220, and / or some combination of the two, such as at an angle between 0 and 90 degrees relative to the centerline axis. More than one pattern of dilution holes may be used simultaneously on the liner. For example, a liner may have one repeating circumferential pattern, another repeating circumferential pattern parallel to the first pattern, and an axial pattern perpendicular to the circumferential pattern. Another liner may have the same type and / or number of dilution hole patterns, or may have a different number and / or type of dilution hole patterns.

[0057] In some embodiments, the repeating pattern can include any number (e.g., between 1 and 3) of converging dilution holes, any number (e.g., between 1 and 3) of diverging dilution holes, and any number (e.g., between 1 and 3) of constant area dilution holes, or one of the three types of dilution holes (converging, diluting, and / or constant area) can be omitted.

[0058] The placement pattern of the dilution holes may also depend on the design of the combustor 230. For example, having more converging dilution holes near the center of each cup to achieve higher jet penetration, and having more diverging holes near the boundaries between the cups to achieve higher diffusion, may be beneficial in some embodiments because in these areas the overall velocity of the airflow is lower, and higher penetration can be achieved at lower velocities.

[0059] In addition, Figure 6 In the embodiment, the dilution hole pattern type on the outer liner 610 is aligned with the dilution hole pattern type on the inner liner 615 (i.e., the converging dilution holes 616, 617 on the outer liner 610 face the converging dilution holes 618, 619 on the inner liner 615, and the diverging dilution holes 620 on the outer liner 610 face the diverging dilution holes 621 on the inner liner 615). However, in other embodiments, a combination of staggered arrangements between the outer liner 610 and the inner liner 615 (i.e., the converging dilution holes on the outer liner face the diverging dilution holes on the inner liner, and vice versa) can further increase the turbulent kinetic energy within the recirculation zone 635. In some embodiments, the dilution hole pattern can also vary in the axial direction to provide additional pressure differential across the recirculation zone 635 along the length of the combustor to achieve better air-fuel mixing, reduce hot and cold spots within the combustion chamber 315, and further reduce NOx emissions.

[0060] Converging dilution holes 616 to 619 Figure 6 615 is conceptually represented by a trapezoidal profile that is wider on the cold side of the liners 610, 615 and narrower on the hot side of the liners 610, 615. Similarly, the diverging dilution holes 620, 621 are Figure 6 615 are conceptually represented by a trapezoidal profile that is wider on the hot side of the liners 610, 615 and narrower on the cold side of the liners 610, 615. In practice, however, the profiles of both the converging and diverging dilution holes may vary in different embodiments, some examples of which are described in more detail below.

[0061] Figure 7A and 7B Shown Figure 4 1 and 2. Embodiments of varying dilution holes 701, 702, 703, 704 in the liner 705 of the combustion chamber 315. Figure 7A Provides a cool side 707 (see Figure 7B ) (outside the combustion chamber 315) to the hot side 708 of the liner 705 (see Figure 7B ) (Inside the combustion chamber 315) View toward the centerline axis 220. Figure 7B Shown is a view of the combustion chamber 315 taken along line 7B-7B from the rear to the front. Figure 7ACross-section of dilution holes 701, 702, 703, 704 in FIG. Liner 705 can be an outer liner or an inner liner. Dilution holes 701 to 704 are shown along Figure 4 The dilution holes are arranged in the circumferential direction of the burner 230 , and additional dilution holes (not shown) may also be arranged in the axial direction of the burner 230 .

[0062] Air from the high pressure compressor flows in an axial direction (indicated by arrow 710 ) along the cold side 707 of the liner 705 , enters the dilution holes 701 to 704 in a lateral direction (indicated by arrow 711 ), and exits the dilution holes 701 to 704 on the hot side 708 of the liner 705 into the combustion chamber 315 .

[0063] The dilution holes 701-704 include converging dilution holes 701, 702 and diverging dilution holes 703, 704. In this embodiment, the converging dilution holes 701, 702 are inserts with cold chutes 713, 714 extending above the surface of the cold side 707 of the liner 705. In this case, the converging dilution holes 701, 702 lack any hot side chutes. The converging dilution holes 701, 702 have circular inlet orifices 715, 716 on the cold side 707 of the liner 705 and circular outlet orifices 717, 718 on the hot side 708 of the liner 705. The diameter of the inlet orifices 715, 716 is larger than the diameter of the outlet orifices 717, 718. Thus, the diameter of the converging dilution holes 701 , 702 decreases linearly, resulting in the converging dilution holes 701 , 702 having a trapezoidal profile that is narrower on the hot side 708 of the liner 705 and wider on the cold side 707 of the liner 705 .

[0064] Note that the outlet openings 717, 718 and the corresponding inlet openings 715, 716 are Figure 7A Depicted with solid circles in FIG, to indicate that two orifices are directly visible in this view.

[0065] In this embodiment, the diverging dilution holes 703, 704 are also inserts, with cold chutes 721, 722 extending above the surface of the cold side 707 of the liner 705. In this case, the diverging dilution holes 703, 704 lack any hot side chutes. The diverging dilution holes 703, 704 have circular inlet orifices 723, 724 on the cold side 707 of the liner 705 and circular outlet orifices 725, 726 on the hot side 708 of the liner 705. The diameter of the diverging dilution holes 703, 704 decreases linearly from the inlet orifices 723, 724 to the surface of the cold side 707, and then increases linearly from the cold side 707 to the surface of the hot side 708. Thus, the diverging dilution holes 703, 704 have a double trapezoidal profile, which is wider at the orifices 723-726 but narrower in the middle. The wider inlet apertures 723 , 724 allow more air to enter the diverging dilution holes 703 , 704 , which further increases the diffusion of air from the outlet apertures 725 , 726 .

[0066] Note that the outlet openings 725, 726 are Figure 7A 724 to indicate that in this example, their diameters are larger than the diameters of the corresponding inlet orifices 723, 724, and therefore the outlet orifices 725, 726 are not directly visible in this view. However, in some embodiments, the diameters of the outlet orifices 725, 726 may be smaller than the diameters of the corresponding inlet orifices 723, 724, depending on the geometry of the cold chutes 721, 722, since the inlet orifices 723, 724 are located at the ends of the cold chutes 721, 722.

[0067] In this example, all dilution holes 701, 702, 703, 704 are inserts, with cold chutes 713, 714, 721, 722. However, similar arrangements of varying converging and diverging dilution holes are possible, where the dilution holes are not inserts. Furthermore, the dilution holes may have hot side chutes in addition to or in place of the cold side chutes, or may have no chutes at all.

[0068] In various embodiments, the inlet shapes of the converging and diverging dilution holes can be rounded, chamfered, and / or bell-shaped to improve inlet streamlines and better align the flow. Converging dilution holes can variously have straight holes, converging channels, or contoured converging rectangular elliptical racetrack designs. Diverging dilution holes can have wavy and / or non-wavy cross-sections, converging and / or diverging cross-sections, and multiple holes at the inlet to form a grid across the surface. The cross-sectional profile of the diverging dilution holes can be a linear, diverging cross-section or a smoothly varying curve.

[0069] In various embodiments, the converging and diverging dilution holes may have a different profile in the circumferential direction than in the axial direction, and the inlet and / or outlet apertures may have shapes other than circular, including triangles, ellipses, rectangular ovals (i.e., "racetracks"), and other geometric shapes rotated at any suitable angle relative to the circumferential or axial directions. Some embodiments also vary the shape and angle of the outlet apertures to further optimize the diffusion and penetration patterns.

[0070] The transverse cross-sectional area of ​​the dilution hole changes continuously from the inlet hole to the outlet hole as the shape changes from one geometry and / or size at the inlet hole to another geometry and / or size at the outlet hole. When both holes have circular profiles, the cross-sectional profile changes linearly. When the holes have different geometries, the cross-sectional profile can change nonlinearly or piecewise linearly. For example, a trapezoidal profile has a piecewise linear profile, while an hourglass profile has a nonlinear profile. For a converging dilution hole, the ratio of the transverse cross-sectional area of ​​the inlet hole to the outlet hole is generally greater than 1. For a diverging dilution hole, the ratio of the transverse cross-sectional area of ​​the inlet hole to the outlet hole is generally less than 1.

[0071] The dilution hole design is available in the form of an insert with the cold side chute having a top hat profile. In a preferred embodiment, the height of the cold side chute can be in the range of 100 mm to 250 mm above the cold side surface, depending on the burner channel velocity. The insert can also be formed in the form of a hot side chute with an inverted top hat profile. This allows for better diffusion within the core of the burner. Since the hot side chute is exposed to higher temperatures, various cooling solutions can be used, such as slots in the chute. In a preferred embodiment, the height on the hot side can be in the range of 50 mm to 350 mm above the hot side surface. Based on the burner design, each design can have cold side features, hot side chute features, or both to achieve the desired flow field.

[0072] In some embodiments, individual panels of dilution holes may be formed with an aerodynamic foil shape, with suction and pressure sides simulating the same flow behavior and generating a circumferential pressure gradient at a given radial position.

[0073] The location and pattern of diverging and converging dilution holes, the geometry of the inlet and outlet orifices, and additional features such as cold and hot chutes are all variables that can be optimized for each turbine engine design. For example, these variables can be selected to selectively reduce the turbine engine's speed when operating at critical speeds (e.g., during takeoff and landing of an aircraft). Figure 4 Hot spots within the combustion chamber 315. Existing turbine engines can also be retrofitted using the inserts to improve the characteristics of their combustion chamber 315 and overall performance.

[0074] Figure 8A 、 8B , 9A, 9B, 10A, 10B, 11A and 11B schematically show some additional embodiments of convergent dilution holes and divergent dilution holes. These embodiments are similar to those described above with respect to Figure 7A and 7B The present invention relates to the embodiments described herein, and the same reference numerals have been used to refer to the same or similar components. Detailed descriptions of some of these components will be omitted, and the following discussion will focus on the differences between these embodiments. Any of the various features discussed in conjunction with any one of the embodiments discussed herein may also be applied to and used with any other embodiment.

[0075] Figure 8A and 8B Shown Figure 4 Another embodiment of varying dilution holes 801 , 802 , 803 , 804 in the liner 805 of the combustion chamber 315 . Figure 8A Provides a cool side 807 (see Figure 8B ) (outside the combustion chamber 315) to the hot side 808 of the liner 805 (see Figure 8B ) (inside the combustion chamber 315) toward the centerline axis 220 (see Figure 4 ) view. Figure 8B Shown is a view of the combustion chamber 315 taken along line 8B-8B from the rear to the front. Figure 8A The cross section of the dilution holes 801, 802, 803, 804 in FIG. 805 can be an outer liner or an inner liner. The dilution holes 801 to 804 are shown as being arranged along the circumferential direction of the burner 230. Additional dilution holes (not shown) can also be arranged along the axial direction of the burner 230 (see FIG. 806 ). Figure 4 ).

[0076] Air from the high pressure compressor flows in an axial direction (indicated by arrow 810 ) along the cold side 807 of the liner 805 , enters the dilution holes 801 to 804 in a lateral direction (indicated by arrow 811 ), and exits the dilution holes 801 to 804 on the hot side 808 of the liner 805 into the combustion chamber 315 .

[0077] The dilution holes 801 to 804 include convergent dilution holes 801, 802 and divergent dilution holes 803, 804. The convergent dilution holes 801, 802 in this example are similar to those in the embodiment of FIG. Figure 7A and 7B805 . In this embodiment, the diverging dilution holes 803, 804 are also inserts, with cold chutes 821, 822 extending above the surface of the cold side 807 of the liner 805. In this case, the diverging dilution holes 803, 804 lack any hot side chutes. The diverging dilution holes 803, 804 have circular inlet orifices 823, 824 on the cold side 807 of the liner 805 and circular outlet orifices 825, 826 on the hot side 808 of the liner 805. In addition, the diverging dilution holes 803, 804 each have a porous grid 833, 834 forming a mesh surface across the inlet orifices 823, 824.

[0078] The diameter of the diverging dilution holes 803, 804 decreases smoothly from the inlet orifices 823, 824 to the surface of the cold side 807, and then increases smoothly from the cold side 807 to the surface of the hot side 808. Thus, the diverging dilution holes 803, 804 have an hourglass profile that is wider at the orifices 823-826 but narrower in the middle. The wider inlet orifices 823, 824 allow more air to enter the diverging dilution holes 803, 804, which further increases the diffusion of the air from the outlet orifices 825, 826. In addition, the porous grids 833, 834 provide an additional pressure differential at the inlet of the diverging dilution holes 803, 804, which causes the velocity to be further reduced and, therefore, further increases the diffusion of the air upon exiting. By adding the porous grids 833, 834, the reduced pressure also reduces the penetration of cold air into the combustion chamber 315, which helps to offset hot spots near the liner 805.

[0079] In some embodiments, the porous grids 833, 834 provide a sufficient pressure differential so that the diverging dilution holes 803, 804 do not need to have a varying cross-sectional area from the inlet orifice to the outlet orifice in order to provide diffusion of air from the outlet orifices 825, 826. In such embodiments, the diameter of the diverging dilution holes 803, 804 can remain constant from the cold side 807 to the hot side 808 and have a diameter similar to Figure 5B The rectangular outline shown in .

[0080] Note that the outlet openings 825, 826 are Figure 8A 824, and therefore, the outlet orifices 825, 826 are not directly visible in this view. However, in some embodiments, the diameter of the outlet orifices 825, 826 may be smaller than the diameter of the corresponding inlet orifices 823, 824, depending on the geometry of the cold chutes 821, 822, since the inlet orifices 823, 824 are located at the ends of the cold chutes 821, 822.

[0081] Figure 9A and 9BShown Figure 4 Another embodiment of varying dilution holes 901 , 902 , 903 , 904 in a liner 905 of a combustion chamber 315 . Figure 9A Provides a cool side 907 (see Figure 9B ) (outside the combustion chamber 315) to the hot side 908 of the liner 905 (see Figure 9B ) (inside the combustion chamber 315) toward the centerline axis 220 (see Figure 4 ) view. Figure 9B Shown is a view of the combustion chamber 315 taken along line 9B-9B from the rear to the front. Figure 9A Cross-section of dilution holes 901, 902, 903, 904 in FIG. Liner 905 may be an outer liner or an inner liner. Dilution holes 901 to 904 are shown along the combustor 230 (see FIG. Figure 4 ), and additional dilution holes (not shown) may also be arranged along the axial direction of the combustor 230.

[0082] Air from the high pressure compressor flows in an axial direction (indicated by arrow 910 ) along the cold side 907 of the liner 905 , enters the dilution holes 901 to 904 in a lateral direction (indicated by arrow 911 ), and exits the dilution holes 901 to 904 on the hot side 908 of the liner 905 into the combustion chamber 315 .

[0083] The dilution holes 901 to 904 include convergent dilution holes 901, 902 and divergent dilution holes 903, 904. The convergent dilution holes 901, 902 in this example are similar to those in the embodiment of FIG. Figure 7A and 7B 905 . In this embodiment, the diverging dilution holes 903, 904 are also inserts, with cold chutes 921, 922 extending above the surface of the cold side 907 of the liner 905. In this case, the diverging dilution holes 903, 904 lack any hot side chutes. The diverging dilution holes 903, 904 have circular inlet orifices 923, 924 on the cold side 907 of the liner 905 and circular outlet orifices 925, 926 on the hot side 908 of the liner 905. In addition, the diverging dilution holes 903, 904 each have a porous grid 933, 934 forming a mesh surface across the inlet orifices 923, 924.

[0084] The diameter of the diverging dilution holes 903, 904 decreases linearly from the inlet orifices 923, 924 to the surface of the cold side 907, and then increases linearly from the cold side 907 to the surface of the hot side 908. Therefore, the diverging dilution holes 903, 904 have a double trapezoidal profile, which is wider at the orifice but narrower in the middle. The wider inlet orifices 923, 924 allow more air to enter the diverging dilution holes 903, 904, which further increases the diffusion of air from the outlet orifices 925, 926.

[0085] Note that the outlet openings 925, 926 are Figure 9A 924 are depicted with dashed circles to indicate that in this example, their diameters are larger than the diameters of the corresponding inlet orifices 923, 924, and therefore the outlet orifices 925, 926 are not directly visible in this view. However, in some embodiments, the diameters of the outlet orifices 925, 926 may be smaller than the diameters of the corresponding inlet orifices 923, 924, depending on the geometry of the cold chutes 921, 922, since the inlet orifices 923, 924 are located at the ends of the cold chutes 921, 922.

[0086] Figure 10A and 10B Shown Figure 4 Another embodiment of varying dilution holes 1001 , 1002 , 1003 , 1004 in a liner 1005 of a combustion chamber 315 . Figure 10A Provides a cool side 1007 (see Figure 10B ) (outside the combustion chamber 315) to the hot side 1008 of the liner 1005 (see Figure 10B ) (Inside the combustion chamber 315) View toward the centerline axis 220. Figure 10B Shown is a view of the combustion chamber 315 taken along line 10B-10B from the rear to the front. Figure 10A Figure 1 shows a cross section of dilution holes 1001, 1002, 1003, and 1004 in the combustor 230. Liner 1005 may be an outer liner or an inner liner. Dilution holes 1001 to 1004 are shown as being arranged along the circumferential direction of combustor 230, and additional dilution holes (not shown) may also be arranged along the axial direction of combustor 230.

[0087] Air from the high pressure compressor flows in an axial direction (indicated by arrow 1010 ) along the cold side 1007 of the liner 1005 , enters the dilution holes 1001 to 1004 in a lateral direction (indicated by arrow 1011 ), and exits the dilution holes 1001 to 1004 on the hot side 1008 of the liner 1005 into the combustion chamber 315 .

[0088] The dilution holes 1001 to 1004 include convergent dilution holes 1001, 1002 and divergent dilution holes 1003, 1004. The convergent dilution holes 1001, 1002 in this example are similar to those in the embodiment of FIG. Figure 7A and 7B Converging dilution holes 701, 702 are depicted.

[0089] In this embodiment, the diverging dilution holes 1003, 1004 are also inserts, with the cold chutes 1021, 1022 extending above the surface of the cold side 1007 of the liner 1005. In this case, the diverging dilution holes 1003, 1004 do not have any hot side chutes. The diverging dilution holes 1003, 1004 have rectangular oval (i.e., "racetrack") shaped inlet apertures 1023, 1024 on the cold side 1007 of the liner 1005, and racetrack-shaped outlet apertures 1025, 1026 on the hot side 1008 of the liner 1005. In this example, the minor axis of the racetrack of the inlet apertures 1023, 1024 is equal to the minor axis of the racetrack of the outlet apertures 1025, 1026 and is aligned in the axial direction (e.g., parallel to arrow 1010). The long axes of the racetracks of inlet apertures 1023, 1024 are smaller than the long axes of the racetracks of outlet apertures 1025, 1026 and are aligned in the circumferential direction. Note that outlet apertures 1025, 1026 are depicted with dashed outlines in FIG10 to indicate that outlet apertures 1025, 1026 are not directly visible in this view.

[0090] Because the major axis of the outlet orifices 1025, 1026 is greater than the major axis of the inlet orifices 1023, 1024, the circumferential diameter of the diverging dilution holes 1003, 1004 increases linearly from the inlet orifices 1023, 1024 to the surface of the cold side 1007, and then to the outlet orifices 1025, 1026 at the surface of the hot side 1008. Therefore, the diverging dilution holes 1003, 1004 have a trapezoidal profile that is wider on the hot side 1008 of the liner 1005 and narrower on the cold side 1007 of the liner 1005. The combination of circular converging dilution holes for higher penetration and racetrack diverging dilution holes for higher dilution jet late diffusion helps control penetration and circumferential diffusion to reduce high temperatures in the core of the combustor 315 and near the hot side 1008 of the liner 1005.

[0091] As described above, the minor axis of the outlet orifices 1025, 1026 is equal to the diameter of the corresponding inlet orifices 1023, 1024. However, in some embodiments of the diverging dilution holes 1003, 1004, the minor axis of the outlet orifices 1025, 1026 may be smaller or larger than the diameter of the corresponding inlet orifices 1023, 1024, depending on the geometry of the cold chutes 1021, 1022, since the inlet orifices 1023, 1024 are located at the ends of the cold chutes 1021, 1022.

[0092] Figure 11A and 11B Shown Figure 4 Another embodiment of varying dilution holes 1101 , 1102 , 1103 , 1104 in the liner 1105 of the combustion chamber 315 . Figure 11A Provides a cool side 1107 (see Figure 11B ) (outside the combustion chamber 315) to the hot side 1108 of the liner 1105 (see Figure 11B ) (Inside the combustion chamber 315) View toward the centerline axis 220. Figure 11B Shown is a view of the combustion chamber 315 taken along line 11B-11B from the rear to the front. Figure 11A The cross section of the dilution holes 1101, 1102, 1103, 1104 in FIG. The liner 1105 can be an outer liner or an inner liner. The dilution holes 1101 to 1104 are shown to be arranged along the circumferential direction of the combustor 230 (see FIG. Figure 4 ), additional dilution holes (not shown) may also be arranged along the axial direction of the burner 230.

[0093] Air from the high pressure compressor flows in an axial direction (indicated by arrow 1110 ) along the cold side 1107 of the liner 1105 , enters the dilution holes 1101 to 1104 in a lateral direction (indicated by arrow 1111 ), and exits the dilution holes 1101 to 1104 on the hot side 1108 of the liner 1105 into the combustion chamber 315 .

[0094] The dilution holes 1101 to 1104 include converging dilution holes 1101, 1102 and diverging dilution holes 1103, 1104. The converging dilution holes 1101, 1102 in this example are similar to the converging dilution holes 701, 702 described with respect to Figures 7A and 7B.

[0095] In this embodiment, the diverging dilution holes 1103, 1104 are also inserts, with the cold chutes 1121, 1122 extending above the surface of the cold side 1107 of the liner 1105. In this case, the diverging dilution holes 1103, 1104 do not have any hot side chutes. The diverging dilution holes 1103, 1104 have circular inlet orifices 1123, 1124 on the cold side 1107 of the liner 1105 and racetrack-shaped outlet orifices 1125, 1126 on the hot side 1108 of the liner 1105. The minor axes of the racetracks of the outlet orifices 1125, 1126 are aligned in the axial direction (e.g., parallel to arrow 1110), and the major axes of the racetracks of the outlet orifices 1125, 1126 are aligned in the circumferential direction. In this example, the diameter of the inlet apertures 1123, 1124 is larger than the minor axis of the racetrack of the outlet apertures 1125, 1126. The diameter of the inlet apertures 1123, 1124 is smaller than the major axis of the racetrack of the outlet apertures 1125, 1126. In some embodiments, the inlet apertures 1123, 1124 have chamfered edges for smoother airflow entry, and the outlet apertures 1125, 1126 are smoothly rounded to further improve lateral diffusion.

[0096] Note that the portion of the outlet openings 1125, 1126 is Figure 11A 1124 to indicate that in this example, their long axes are larger than the long axes of the corresponding diameters of the inlet orifices 1123, 1124, and therefore, portions of the outlet orifices 1125, 1126 are not directly visible in this view. However, in some embodiments of the diverging dilution holes 1103, 1104, the diameters of the inlet orifices 1123, 1124 may be equal to or larger than the long axes of the raceways of the outlet orifices 1125, 1126, depending on the geometry of the cold chutes 1121, 1122, since the inlet orifices 1123, 1124 are located at the ends of the cold chutes 1121, 1122.

[0097] Because the diameter of the inlet apertures 1123, 1124 is smaller than the long axis of the raceway of the outlet apertures 1125, 1126, the circumferential diameter of the diverging dilution holes 1103, 1104 increases nonlinearly from the inlet apertures 1123, 1124, to the surface of the cold side 1107, and to the surface of the hot side 1108. As a result, the diverging dilution holes 1103, 1104 have a bell-shaped profile that is narrower on the hot side 1108 of the liner 1105 and wider on the cold side 1107 of the liner 1105.

[0098] Further aspects of the disclosure are provided by the subject matter of the following clauses.

[0099] A combustor for a turbine engine, the combustor comprising: a combustion chamber; a liner forming a boundary of the combustion chamber; and a plurality of dilution holes through the liner to allow airflow into the combustion chamber, wherein the plurality of dilution holes include converging dilution holes having a converging cross-sectional profile and diverging dilution holes having a diverging cross-sectional profile.

[0100] The combustor of the preceding clause, wherein at least one of the diverging dilution holes has a cross-sectional profile that is one of rectangular, trapezoidal, hourglass-shaped, and double-trapezoidal.

[0101] The combustor of any preceding clause, wherein the liner is one of an outer liner and an inner liner, the outer liner and the inner liner both having a cylindrical shape about a centerline axis of the turbine engine, the outer liner having a radius greater than a radius of the inner liner, an outer boundary of an annular volume of the combustion chamber being defined by the outer liner, and an inner boundary of the annular volume of the combustion chamber being defined by the inner liner, wherein the plurality of dilution holes are arranged in a repeating pattern on the liner, the repeating pattern having a first number of converging dilution holes and a second number of diverging dilution holes.

[0102] The combustor of any preceding clause, wherein the repeating pattern is one of a circumferential pattern arranged on the liner about the centerline axis of the turbine engine and an axial pattern arranged on the liner along the centerline axis of the turbine engine, wherein the plurality of dilution holes further includes constant area dilution holes having a constant cross-sectional profile, and the repeating pattern includes a third number of constant area dilution holes.

[0103] The combustor of any preceding clause, wherein the first number of converging dilution holes is between 1 and 3, the second number of diverging dilution holes is between 1 and 3, and the third number of constant area dilution holes is between 1 and 3.

[0104] The combustor of any preceding clause, wherein the liner is the outer liner, the repeating pattern is a first repeating pattern, the plurality of dilution holes are arranged in the first repeating pattern on the outer liner, and the combustor further comprises: an inner liner; and a second plurality of dilution holes passing through the inner liner to allow airflow into the combustion chamber, the second plurality of dilution holes comprising converging dilution holes and diverging dilution holes arranged in a second repeating pattern on the inner liner.

[0105] The combustor of any preceding clause, wherein the first repeating pattern on the outer liner and the second repeating pattern on the inner liner each alternate between a single converging dilution hole and a single diverging dilution hole, the diverging dilution holes on the outer liner being arranged opposite the diverging dilution holes on the inner liner, and the converging dilution holes on the outer liner being arranged opposite the converging dilution holes on the inner liner.

[0106] The combustor of any preceding clause, wherein the diverging dilution holes on the outer liner are arranged opposite the diverging dilution holes on the inner liner, and the converging dilution holes on the outer liner are arranged opposite the converging dilution holes on the inner liner.

[0107] The combustor of any preceding clause, wherein the diverging dilution holes on the outer liner are arranged opposite the converging dilution holes on the inner liner, and the diverging dilution holes on the outer liner are arranged opposite the converging dilution holes on the inner liner.

[0108] The combustor of any preceding clause, wherein each dilution hole of the plurality of dilution holes has an inlet aperture on a cold surface of the liner outside the combustion chamber and an outlet aperture on a hot surface of the liner inside the combustion chamber.

[0109] The combustor of any preceding clause, wherein at least one of the plurality of dilution holes is an insert extending through an existing hole in the liner from the cold surface to the hot surface.

[0110] The combustor of any preceding clause, wherein the insert comprises at least one of a cold chute extending beyond the cold surface outside the combustion chamber and a hot chute extending beyond the hot surface inside the combustion chamber.

[0111] The combustor of any preceding clause, wherein the inlet orifice of at least one of the converging dilution holes has a first area and the outlet orifice of the at least one converging dilution hole has a second area, the second area being smaller than the first area, and wherein the inlet orifice of at least one of the diverging dilution holes has a third area and the outlet orifice of the at least one diverging dilution hole has a fourth area, the fourth area being larger than the third area.

[0112] The combustor of any preceding clause, wherein at least one of the inlet aperture and the outlet aperture of at least one of the plurality of dilution holes is one of a circular aperture, a chamfered aperture, and a bell-shaped aperture.

[0113] The combustor of any preceding clause, wherein the shape of at least one of the inlet aperture and the outlet aperture of at least one of the diverging dilution holes is one of a circle and a racetrack.

[0114] The combustor of any preceding clause, wherein at least one of the diverging dilution holes has a grid across the inlet aperture, and wherein air entering the dilution hole through the grid across the inlet aperture is reduced in velocity within the dilution hole to create a high pressure region near the outlet aperture on the hot surface of the liner within the combustion chamber.

[0115] A combustor according to any preceding clause, wherein air entering the combustion chamber through converging dilution holes has its velocity increased to create a low pressure region near the outlet orifice on the hot surface of the liner within the combustion chamber, wherein air entering the combustion chamber through diverging dilution holes has its velocity reduced to create a high pressure region near the outlet orifice on the hot surface of the liner within the combustion chamber, and wherein gases within the combustion chamber stretch toward and deflect away from the low pressure region.

[0116] A turbomachine engine comprises: (A) a compressor section; (B) a fan assembly providing intake air to the compressor section; (C) a turbine section driving the compressor section; and (D) a combustor arranged to receive compressed air from the compressor section and provide hot gas to the turbine section. The combustor comprises: (a) a combustion chamber; (b) a liner forming a boundary of the combustion chamber; and (c) a plurality of dilution holes passing through the liner to allow airflow into the combustion chamber, wherein the plurality of dilution holes comprises converging dilution holes and diverging dilution holes, the converging dilution holes having a converging cross-sectional profile and the diverging dilution holes having a diverging cross-sectional profile.

[0117] The turbine engine of the preceding clause, wherein the liner is one of an outer liner and an inner liner, the outer liner and the inner liner both having a cylindrical shape about a centerline axis of the turbine engine, the outer liner having a radius greater than a radius of the inner liner, an outer boundary of an annular volume of the combustion chamber being defined by the outer liner, and an inner boundary of the annular volume of the combustion chamber being defined by the inner liner, wherein the plurality of dilution holes are arranged in a repeating pattern on the liner, the repeating pattern having a first number of converging dilution holes and a second number of diverging dilution holes.

[0118] A turbine engine according to any preceding clause, wherein the repeating pattern is one of a circumferential pattern arranged on the liner about the centerline axis of the turbine engine and an axial pattern arranged on the liner along the centerline axis of the turbine engine.

[0119] Although the foregoing description is directed to preferred embodiments, it should be noted that other variations and modifications are apparent to those skilled in the art and may be made without departing from the spirit or scope of the present disclosure. In addition, features described in conjunction with one embodiment may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A combustor for a turbine engine, characterized in that: The burner comprises: combustion chamber; a liner forming a boundary of the combustion chamber; and a plurality of dilution holes through the liner to allow airflow into the combustion chamber, wherein each of the plurality of dilution holes has an inlet orifice on a cold surface of the liner outside the combustion chamber and an outlet orifice on a hot surface of the liner inside the combustion chamber, and The plurality of dilution holes include converging dilution holes having a converging cross-sectional profile that is wider at the cold surface of the liner and narrower at the hot surface of the liner, and diverging dilution holes having a diverging cross-sectional profile that is wider at the hot surface of the liner and narrower at the cold surface of the liner.

2. The burner according to claim 1, characterized in that At least one of the diverging dilution holes has a cross-sectional profile that is one of a trapezoidal shape, an hourglass shape, and a double trapezoidal shape.

3. The burner according to claim 1, characterized in that wherein the liner is one of an outer liner and an inner liner, both the outer liner and the inner liner having a cylindrical shape about a centerline axis of the turbine engine, the radius of the outer liner being greater than the radius of the inner liner, an outer boundary of an annular volume of the combustion chamber being defined by the outer liner, and an inner boundary of the annular volume of the combustion chamber being defined by the inner liner, and The plurality of dilution holes are arranged in a repeating pattern on the liner, the repeating pattern having a first number of converging dilution holes and a second number of diverging dilution holes.

4. The burner according to claim 3, characterized in that wherein the repeating pattern is one of a circumferential pattern about the centerline axis of the turbine engine and an axial pattern along the centerline axis of the turbine engine, wherein the plurality of dilution holes further comprises constant area dilution holes having a constant cross-sectional profile, and wherein the repeating pattern comprises a third number of constant area dilution holes.

5. The burner according to claim 4, characterized in that The first number of converging dilution holes is between 1 and 3, the second number of diverging dilution holes is between 1 and 3, and the third number of constant area dilution holes is between 1 and 3.

6. The burner according to claim 3, characterized in that wherein the liner is the outer liner, the repeating pattern is a first repeating pattern, the plurality of dilution holes are arranged in the first repeating pattern, and the combustor further comprises: the lining; and a second plurality of dilution holes through the liner to allow airflow into the combustion chamber, The second plurality of dilution holes includes converging dilution holes and diverging dilution holes arranged in a second repeating pattern on the liner.

7. The burner according to claim 6, characterized in that wherein the first repeating pattern on the outer liner and the second repeating pattern on the inner liner each alternate between a single converging dilution hole and a single diverging dilution hole, the diverging dilution holes through the outer liner are arranged opposite the diverging dilution holes through the inner liner, and the converging dilution holes through the outer liner are arranged opposite the converging dilution holes through the inner liner.

8. The burner according to claim 6, characterized in that The diverging dilution holes through the outer liner are arranged opposite to the diverging dilution holes through the inner liner, and the converging dilution holes through the outer liner are arranged opposite to the converging dilution holes through the inner liner.

9. The burner according to claim 6, characterized in that The diverging dilution holes through the outer liner are arranged opposite to the converging dilution holes through the inner liner, and the diverging dilution holes through the outer liner are arranged opposite to the converging dilution holes through the inner liner.

10. The burner according to claim 1, characterized in that Wherein at least one of the plurality of dilution holes is an insert that extends through an existing hole in the liner from the cold surface to the hot surface.

11. The burner according to claim 10, characterized in that wherein the insert includes at least one of a cold chute extending beyond the cold surface outside the combustion chamber and a hot chute extending beyond the hot surface inside the combustion chamber.

12. The burner according to claim 1, characterized in that At least one of the inlet orifice and the outlet orifice of at least one dilution hole among the plurality of dilution holes is one of a circular orifice, a chamfered orifice, and a bell-shaped orifice.

13. The burner according to claim 1, characterized in that At least one of the inlet orifice and the outlet orifice of at least one of the diverging dilution holes has a shape selected from the group consisting of a circle and a racetrack.

14. The burner according to claim 1, characterized in that wherein air entering the combustion chamber through converging dilution holes increases in velocity to create a low pressure region proximate the exit orifice on the hot surface of the liner within the combustion chamber, wherein air entering the combustion chamber through diverging dilution holes reduces its velocity to create a high pressure region proximate the exit orifice on the hot surface of the liner within the combustion chamber, and The gas in the combustion chamber extends toward the low-pressure region and deflects away from the high-pressure region.

15. A turbine engine, characterized in that: include: (A) Compressor section; (B) a fan assembly providing intake air to the compressor section; (C) a turbine section driving the compressor section; as well as (D) a combustor arranged to receive compressed air from the compressor section and provide hot gas to the turbine section, the combustor comprising: (a) Combustion chamber; (b) a liner forming a boundary of the combustion chamber; and (c) a plurality of dilution holes through the liner to allow airflow into the combustion chamber, wherein each of the plurality of dilution holes has an inlet orifice on a cold surface of the liner outside the combustion chamber and an outlet orifice on a hot surface of the liner inside the combustion chamber, and The plurality of dilution holes include converging dilution holes having a converging cross-sectional profile that is wider at the cold surface of the liner and narrower at the hot surface of the liner, and diverging dilution holes having a diverging cross-sectional profile that is wider at the hot surface of the liner and narrower at the cold surface of the liner.

16. The turbine engine according to claim 15, characterized in that wherein the liner is one of an outer liner and an inner liner, both the outer liner and the inner liner having a cylindrical shape about a centerline axis of the turbine engine, the radius of the outer liner being greater than the radius of the inner liner, an outer boundary of an annular volume of the combustion chamber being defined by the outer liner, and an inner boundary of the annular volume of the combustion chamber being defined by the inner liner, and The plurality of dilution holes are arranged in a repeating pattern on the liner, the repeating pattern having a first number of converging dilution holes and a second number of diverging dilution holes.

17. The turbine engine according to claim 16, characterized in that Wherein the repeating pattern is one of a circumferential pattern around the centerline axis of the turbine engine and an axial pattern along the centerline axis of the turbine engine.

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