Turbofan engine with angled inlet pre-swirling impeller blades

Abstract

A turbofan engine is provided. The turbofan engine includes a fan having a plurality of fan blades; a turbine operatively coupled to the fan to drive the fan, the turbine having a compressor section, a combustion section and a turbine section in series flow sequence and together defining a core airflow path; a nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius and a longitudinal axis; and an inlet pre-swirl impeller located upstream of the plurality of fan blades and defining a chord, the inlet pre-swirl impeller being coupled to the nacelle, wherein the inlet pre-swirl impeller forms a first angle with respect to the radius of the nacelle, and wherein the chord of the inlet pre-swirl impeller forms a second angle with respect to the longitudinal axis of the nacelle.

Description

Technical Field

[0001] This topic generally relates to a gas turbine engine, or more specifically to a gas turbine engine configured to direct airflow at the nacelle entrance and direct incoming objects to the outer part of the engine and away from the engine core. Background Technology

[0002] A turbofan engine typically comprises a fan and a turbine with multiple fan blades arranged in flow communication with each other. Furthermore, the turbine of a turbofan engine typically includes, in series flow sequence, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is supplied from the fan to the inlet of the compressor section, where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are then directed from the combustion section to the turbine section. The flow of combustion gases through the turbine section drives the turbine section and is then directed through the exhaust section to, for example, the atmosphere. Attached Figure Description

[0003] The specification sets forth a complete and practical disclosure for those skilled in the art, including its best mode, which is referenced in the accompanying drawings, wherein:

[0004] Figure 1 This is a schematic cross-sectional view of an exemplary gas turbine engine according to an exemplary embodiment of this subject matter.

[0005] Figure 2 This is an exemplary embodiment based on this topic. Figure 1 A close-up schematic cross-sectional view of the front end of an exemplary gas turbine engine.

[0006] Figure 3 This is along the exemplary embodiments of this topic. Figure 1 The axial direction of the gas turbine engine Figure 1 A schematic diagram of the inlet of an exemplary gas turbine engine.

[0007] Figure 4 This is a schematic diagram of the inlet of a gas turbine engine according to another exemplary embodiment of the present disclosure.

[0008] Figure 5 This is along another exemplary embodiment of the subject matter. Figure 1 The axial direction of the gas turbine engine Figure 1 A schematic diagram of the inlet of an exemplary gas turbine engine.

[0009] Figure 6 yes Figure 1A cross-sectional view of a portion span inlet guide vane of an exemplary gas turbine engine at a first position along the span of the portion span inlet guide vane.

[0010] Figure 7 yes Figure 1 A cross-sectional view of a portion-span inlet guide vane of an exemplary gas turbine engine at a second position along the span of the portion-span inlet guide vane.

[0011] Figure 8 This is along another exemplary embodiment of the subject matter. Figure 1 The axial direction of the gas turbine engine Figure 1 A schematic diagram of the inlet of an exemplary gas turbine engine.

[0012] Figure 9 This is along another exemplary embodiment of the subject matter. Figure 1 The axial direction of the gas turbine engine Figure 1 A schematic diagram of the inlet of an exemplary gas turbine engine.

[0013] Figure 10 This is along another exemplary embodiment of the subject matter. Figure 1 The axial direction of the gas turbine engine Figure 1 A schematic diagram of the inlet of an exemplary gas turbine engine.

[0014] Figure 11 This is along another exemplary embodiment of the subject matter. Figure 1 The axial direction of the gas turbine engine Figure 1 A schematic diagram of the inlet of an exemplary gas turbine engine.

[0015] The corresponding reference numerals indicate the respective portions of several views. The examples set forth herein illustrate exemplary embodiments of this disclosure, and such examples should not be construed as limiting the scope of this disclosure in any way. Detailed Implementation

[0016] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. Detailed description uses numerals and letter designations to refer to features in the drawings. Similar or identical reference numerals in the drawings and description have been used to refer to similar or identical portions of the present disclosure.

[0017] The following description is provided to enable those skilled in the art to make and use the described embodiments, which are contemplated for performing this disclosure. However, various modifications, equivalents, variations, and substitutions will be apparent to those skilled in the art. Any and all such modifications, variations, equivalents, and substitutions are intended to fall within the scope of this disclosure.

[0018] The term "exemplary" as used herein means "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as superior or better than other implementations. Furthermore, unless specifically stated otherwise, all embodiments described herein should be considered exemplary.

[0019] For the purposes described below, the terms “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” and their derivatives should be used in relation to the orientation of the disclosure in the accompanying drawings. However, it should be understood that this disclosure may take various alternative variations unless expressly stated to the contrary. It should also be understood that the specific devices shown in the accompanying drawings and described in the following specification are merely exemplary embodiments of this disclosure. Therefore, the specific dimensions and other physical characteristics associated with the embodiments disclosed herein should not be considered limiting.

[0020] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0021] The terms "front" and "rear" refer to relative positions within a gas turbine engine. "Front" refers to the position closer to the engine inlet, while "rear" refers to the position closer to the engine nozzle or exhaust port.

[0022] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction in which the fluid flows.

[0023] The singular forms “one,” “a,” and “the” include plural references unless the context clearly indicates otherwise.

[0024] Furthermore, the terms “low,” “high,” or their respective degrees of comparison (e.g., lower, higher, where applicable) refer to relative speed or pressure within the engine, unless otherwise specified. For example, a “low-pressure turbine” operates at pressures typically lower than a “high-pressure turbine.” Alternatively, unless otherwise specified, the above terms may be understood in their superlative sense. For example, a “low-pressure turbine” may refer to the turbine with the lowest maximum pressure within a turbine section, while a “high-pressure turbine” may refer to the turbine with the highest maximum pressure within a turbine section. The engines disclosed herein may also include intermediate-pressure turbines, such as engines with three spools.

[0025] As used throughout the specification and claims, approximate language is applied to modify any quantitative expression that allows for variation without altering its underlying function. Therefore, values ​​modified by one or more terms such as “approximately,” “about,” and “substantially” are not limited to specified exact values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, approximate language may refer to a margin of 1%, 2%, 4%, 10%, 15%, or 20%. These approximate margins may apply to a single value, to either or both endpoints of a defined numerical range, and / or to a margin within a range between endpoints.

[0026] Throughout this specification and claims, scope limitations are combined and interchanged, and such scopes are identified and include all subscopes contained therein, unless the context or language otherwise indicates. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0027] As used herein, the term "fan pressure ratio" refers to the ratio of the air pressure immediately downstream of the fan blades during fan operation to the air pressure immediately upstream of the fan blades during fan operation.

[0028] As used herein, the term "rated speed" for turbofan engines refers to the maximum rotational speed that a turbofan engine can achieve during normal operation. For example, a turbofan engine can operate at rated speed during maximum load operation, such as during takeoff operations.

[0029] As used in this article, the term "fan tip speed," defined by the multiple fan blades of a fan, refers to the linear velocity of the outer tip of the fan blades in the radial direction during fan operation.

[0030] This disclosure generally relates to an inlet pre-swirl vane configured for use in a turbofan engine with multiple partial-span inlet guide vanes. In this disclosure, the multiple partial-span inlet guide vanes form a first angle relative to the radius of the turbofan engine's outer nacelle. Furthermore, the multiple partial-span inlet guide vanes define a chord, and the chord of the partial-span inlet guide vanes forms a second angle relative to the longitudinal axis of the outer nacelle.

[0031] In this manner, multiple partial-span inlet guide vanes are configured to direct incoming objects toward the outer portion of the turbofan engine. These vanes are also configured to direct incoming objects away from the core airflow path of the turbofan engine and toward a bypass airflow channel. This provides a deflection mechanism that facilitates the intake of objects into the outer portion of the turbofan engine by minimizing the chance of the object traveling to the core of the turbofan engine. These objects may include bird strikes, hail, ice, dust storms, debris, and other foreign objects.

[0032] Furthermore, in this manner, the multiple partial-span inlet guide vanes are also configured to pre-swirl the airflow supplied through the inlet of the outer nacelle (upstream of the multiple fan blades). As discussed herein, pre-swirl the airflow supplied through the inlet of the outer nacelle before it reaches the multiple fan blades reduces separation losses and / or impingement losses, allowing the fan to operate at relatively high fan tip speeds with minimal efficiency losses. Additionally, in this manner, the multiple partial-span inlet guide vanes are also configured to minimize flutter and maintain laminar airflow through the partial-span inlet guide vanes while minimizing turbulence in the inlet.

[0033] Referring now to the accompanying drawings, where the same numerals throughout the drawings indicate the same elements. Figure 1 This is a schematic cross-sectional view of a gas turbine engine according to exemplary embodiments of the present disclosure. More specifically, for Figure 1 In one embodiment, the gas turbine engine is an aircraft turbofan jet engine 10, referred to herein as "turbofan engine 10," configured to be mounted on an aircraft, for example, in an underwing configuration or a tail-mounted configuration. Figure 1 As shown, the turbofan engine 10 defines an axial direction A (extending parallel to a longitudinal centerline 12 for reference), a radial direction R, and a circumferential direction (i.e., the direction extending about the axial direction A; not depicted). Generally, the turbofan engine 10 includes a fan section 14 and a turbine 16 (sometimes or alternatively referred to as the "core turbine engine") disposed downstream of the fan section 14.

[0034] The exemplary turbine 16 shown typically includes a basic tubular housing 18 defining an annular inlet 20. The housing 18 surrounds, in a series flow relationship: a compressor section including a first turbocharger or low-pressure (LP) compressor 22 and a second high-pressure (HP) compressor 24; a combustion section 26; a turbine section including a first high-pressure (HP) turbine 28 and a second low-pressure (LP) turbine 30; and an exhaust nozzle section 32. A high-pressure (HP) shaft 34 drives the HP turbine 28 to the HP compressor 24. A low-pressure (LP) shaft 36 drives the LP turbine 30 to the LP compressor 22. The compressor section, combustion section 26, turbine section, and exhaust nozzle section 32 are arranged in a series flow sequence and together define a core airflow path 37 through the turbine 16. This disclosure is also contemplated for compatibility with engines having intermediate-pressure turbines, such as engines with three spools.

[0035] Still referencing Figure 1 In one embodiment, fan section 14 includes a single-stage fan 38 with variable pitch, to which turbine 16 is operatively coupled to drive fan 38. Fan 38 includes a plurality of rotatable fan blades 40 spaced apart from disk 42. As shown, the fan blades 40 extend generally radially outward from disk 42. Each fan blade 40 is operatively coupled to a suitable actuating member 44, which is configured to collectively, for example, uniformly change the pitch of the fan blade 40, because the fan blades 40 are operatively coupled to a suitable actuating member 44. The fan blades 40, disk 42, and actuating member 44 are operatively rotatable together about longitudinal centerline 12 via a power gearbox 46 through LP shaft 36. Power gearbox 46 includes a plurality of gears for reducing the rotational speed of LP shaft 36 to a more efficient fan rotation speed. Thus, in the illustrated embodiment, turbine 16 is operatively coupled to fan 38 via power gearbox 46.

[0036] In an exemplary embodiment, fan section 14 includes twenty-two (22) or fewer fan blades 40. In some exemplary embodiments, fan section 14 includes twenty (20) or fewer fan blades 40. In some exemplary embodiments, fan section 14 includes eighteen (18) or fewer fan blades 40. In some exemplary embodiments, fan section 14 includes sixteen (16) or fewer fan blades 40. In some exemplary embodiments, it is contemplated that fan section 14 may include other numbers of fan blades 40 for a particular application.

[0037] During operation of the turbofan engine 10, fan 38 defines a fan pressure ratio and the plurality of fan blades 40 each define a fan tip velocity. The exemplary turbofan engine 10 depicted defines a relatively high fan tip velocity and a relatively low fan pressure ratio during operation of the turbofan engine at rated speed. As used herein, the term "fan pressure ratio" refers to the ratio of the air pressure immediately downstream of fan blades 40 during operation of fan 38 to the air pressure immediately upstream of fan blades 40 during operation of fan 38. Figure 1 In the illustrated embodiment, the fan 38 of the turbofan engine 10 defines a relatively low fan pressure ratio. For example, the described turbofan engine 10 defines a fan pressure ratio less than or equal to about 1.5. For example, in some exemplary embodiments, the turbofan engine 10 may define a fan pressure ratio less than or equal to about 1.4. In some exemplary embodiments, it is envisioned that the turbofan engine 10 may define other fan pressure ratios for a particular application. The fan pressure ratio may be the fan pressure ratio of the fan 38 during operation of the turbofan engine 10, such as during operation of the turbofan engine 10 at rated speed.

[0038] As used herein, the term "rated speed" with respect to turbofan engine 10 refers to the maximum rotational speed that turbofan engine 10 can achieve during normal operation. For example, turbofan engine 10 can operate at rated speed during maximum load operation, such as during takeoff operations.

[0039] As used herein, the term "fan tip speed," defined by the plurality of fan blades 40, refers to the linear velocity of the outer tip of the fan blade 40 in the circumferential direction during operation of the fan 38. In exemplary embodiments, the turbofan engine 10 of this disclosure rotates the fan blades 40 of the fan 38 at relatively high rotational speeds. For example, during operation of the turbofan engine 10 at rated speed, the fan tip speed of each of the plurality of fan blades 40 is greater than or equal to 1,000 feet per second and less than or equal to 2,250 feet per second. In some exemplary embodiments, during operation of the turbofan engine 10 at rated speed, the fan tip speed of each fan blade 40 may be greater than or equal to 1,250 feet per second and less than or equal to 2,250 feet per second. In some exemplary embodiments, during operation of the turbofan engine 10 at rated speed, the fan tip speed of each fan blade 40 may be greater than or equal to approximately 1,350 feet per second, for example greater than approximately 1,450 feet per second, for example greater than approximately 1,550 feet per second, and less than or equal to 2,250 feet per second. In some exemplary embodiments, it is envisioned that during operation of the turbofan engine 10 at rated speed, the fan tip speed of each fan blade 40 may be limited to a different range for a particular application.

[0040] Still referencing Figure 1 In an exemplary embodiment, the disk 42 is covered by a rotatable front nacelle or hub 48 having an aerodynamic profile to facilitate airflow through the plurality of fan blades 40. Additionally, the exemplary fan section 14 includes an annular fan housing or outer nacelle 50 that at least partially, and in the described embodiment, circumferentially surrounds at least a portion of the fan 38 and turbine 16.

[0041] More specifically, the outer nacelle 50 includes an inner wall 52, and a downstream section 54 of the inner wall 52 of the outer nacelle 50 extends over the outer portion of the turbine 16 to define a bypass airflow passage 56 therebetween. Additionally, in the illustrated embodiment, the outer nacelle 50 is supported relative to the turbine 16 by a plurality of circumferentially spaced outlet guide vanes 55. The outer nacelle 50 includes an inlet 60 at its leading edge 61.

[0042] During operation of the turbofan engine 10, a volume of air 58 enters the turbofan engine 10 through the inlet 60 of the outer nacelle 50 and / or the fan section 14. As the volume of air 58 passes through the fan blades 40, a first portion of the air 58 is directed or guided into the bypass airflow passage 56 as indicated by arrow 62, and a second portion of the air 58 is directed or guided into the core airflow path 37 as indicated by arrow 64. The ratio between the airflow through the bypass airflow passage 56 (i.e., the first portion of air indicated by arrow 62) and the airflow through the core airflow path 37 (i.e., the second portion of air indicated by arrow 64) is called the bypass ratio.

[0043] Still referencing Figure 1 The compressed second portion of air from the compressor section, indicated by arrow 64, is mixed with fuel and burned in the combustion section to provide combustion gas 66. Combustion gas 66 is guided from combustion section 26 through HP turbine 28, where a portion of the thermal and / or kinetic energy from combustion gas 66 is extracted via a sequential stage of HP turbine stator blades 68 connected to housing 18 and HP turbine rotor blades 70 connected to HP shaft 34, thereby causing HP shaft 34 to rotate and thus supporting the operation of HP compressor 24. Combustion gas 66 is then guided through LP turbine 30, where a second portion of the thermal and kinetic energy from combustion gas 66 is extracted via a sequential stage of LP turbine stator blades 72 connected to housing 18 and LP turbine rotor blades 74 connected to LP shaft 36, thereby causing LP shaft 36 to rotate and thus supporting the operation of LP compressor 22 and / or fan 38.

[0044] Combustion gas 66 is then directed through the injection exhaust nozzle section 32 of turbine 16 to provide propulsive thrust. Simultaneously, as the first portion of air 62 is directed through the bypass airflow passage 56 before exiting from the fan nozzle exhaust section 76 of turbofan 10, the pressure of the first portion of air, indicated by arrow 62, increases significantly, also providing propulsive thrust. HP turbine 28, LP turbine 30, and injection exhaust nozzle section 32 at least partially define the hot gas path 78 for directing combustion gas 66 through turbine 16.

[0045] Still referencing Figure 1 The turbofan engine 10 of this disclosure also provides a pre-swirl in front of the tip of the fan blade 40 as described herein. For example, the turbofan engine 10 further includes inlet pre-swirl impellers, such as configured as a plurality of partial span inlet guide impellers 100, as described in more detail herein.

[0046] In some exemplary embodiments, it should be understood that the exemplary turbofan engine 10 of this disclosure may be a relatively high-power class turbofan engine 10. Therefore, when operating at rated speed, the turbofan engine 10 may be configured to produce relatively large thrust. More specifically, when operating at rated speed, the turbofan engine 10 may be configured to produce at least approximately 20,000 pounds of thrust, for example at least approximately 25,000 pounds of thrust, for example at least approximately 30,000 pounds of thrust, and up to, for example, approximately 150,000 pounds of thrust. Therefore, the turbofan engine 10 may be referred to as a relatively high-power class gas turbine engine.

[0047] Furthermore, it should be understood that Figure 1 The exemplary turbofan engine 10 depicted is merely an example, and in other exemplary embodiments, the turbofan engine 10 may have any other suitable configuration. For example, in some exemplary embodiments, the fan may not be a variable pitch fan, the engine may not include a reduction gearbox (e.g., power gearbox 46) that drives the fan, and may include any other suitable number or arrangement of shafts, spools, compressors, turbines, etc.

[0048] As described above, the turbofan engine 10 of this disclosure also provides a pre-swirl in front of the tip of the fan blade 40. Reference now also... Figure 2 Provided Figure 1 A close-up cross-sectional view of the fan section 14 and the front end of the turbine 16 of an exemplary turbofan engine 10. In an exemplary embodiment, the turbofan engine 10 includes an inlet pre-swirl impeller located upstream of a plurality of fan blades 40 of a fan 38 and coupled to an outer nacelle 50. For example, the inlet pre-swirl impeller may be directly attached, indirectly attached, or integrated into the outer nacelle 50. More specifically, for Figure 1 and Figure 2 In one embodiment, the inlet pre-swirling impeller is configured as a plurality of partial-span inlet guide impellers 100. Each of the plurality of partial-span inlet guide impellers 100 extends cantilevered from the outer nacelle 50 (e.g., from the inner wall 52 of the outer nacelle 50) in an axial direction A, in front of the plurality of fan blades 40 of the fan 38 and behind the inlet 60 of the outer nacelle 50. More specifically, each of the plurality of partial-span inlet guide impellers 100 defines an outer end 102 in a radial direction R and is coupled to the outer nacelle 50 at its radial outer end 102 by a suitable connecting means (not shown). For example, each of the plurality of partial-span inlet guide impellers 100 may be bolted to the inner wall 52 of the outer nacelle 50 at its outer end 102, welded to the inner wall 52 of the outer nacelle 50 at its outer end 102, or coupled to the outer nacelle 50 at its outer end 102 in any other suitable manner.

[0049] Still refer to Figure 2 In an exemplary embodiment, the nacelle assembly 80 of this disclosure includes an outer nacelle 50 and inlet pre-swirling impellers, such as a plurality of partial-span inlet guide impellers 100. Furthermore, for the illustrated embodiment, the plurality of partial-span inlet guide impellers 100 extend generally in a radial direction R from an outer end 102 to an inner end 104 (i.e., the inner end 104 in the radial direction R). Moreover, as will be understood, for the depicted embodiment, each of the plurality of partial-span inlet guide impellers 100 is not connected to an adjacent partial-span inlet guide impeller 100 at its respective inner end 104 (i.e., adjacent partial-span inlet guide impellers 100 do not contact each other at their radially inner ends 104, and no intermediate connecting member, such as a connecting ring, strut, etc., is included at the radially inner ends 104). More specifically, in the described embodiment, each partial span inlet guide vane 100 is fully supported at its respective outer end 102 by its connection to the outer nacelle 50 (and not by any structure extending between adjacent partial span inlet guide vanes 100, for example, at a position inward in the radial direction R at the outer end 102). As will be discussed below, this can reduce the turbulence generated by the partial span inlet guide vanes 100.

[0050] Furthermore, as shown in the figure, each of the plurality of partial-span inlet guide vanes 100 does not extend entirely between the outer nacelle 50 and, for example, the hub 48 of the turbofan engine 10. More specifically, for the described embodiment, each of the plurality of inlet guide vanes defines an inlet guide vane (“IGV”) span 106 in the radial direction R, which refers to the dimension in the radial direction R between the outer end 102 and the inner end 104 of the partial-span inlet guide vane 100 at its leading edge 108. Each of the plurality of partial-span inlet guide vanes 100 also defines a leading edge 108 and a trailing edge 110. Similarly, it should be understood that the plurality of fan blades 40 of the fan 38 defines a fan blade span 112 in the radial direction R, which refers to the dimension in the radial direction R between the radially outer tip and the base of the respective fan blade 40 at its leading edge 114. Each of the plurality of fan blades 40 of the fan 38 also defines a leading edge 114 and a trailing edge 116.

[0051] For the illustrated embodiment, the IGV span 106 is at least about five percent of the fan blade span 112 and up to about fifty-five percent of the fan blade span 112. For example, in some exemplary embodiments, the IGV span 106 may be between about fifteen percent and about forty-five percent of the fan blade span 112, such as between about thirty percent and about forty percent of the fan blade span 112.

[0052] Now will also refer to Figure 3 It provides Figure 1 and Figure 2An axial view of the inlet 60 of the turbofan engine 10. It should be understood that the plurality of partial-span inlet guide vanes 100 of the turbofan engine 10 comprises a relatively large number of partial-span inlet guide vanes 100. For example, in the illustrated embodiment, the plurality of partial-span inlet guide vanes 100 of the turbofan engine 10 comprises thirty-two partial-span inlet guide vanes 100. In other exemplary embodiments, it is envisioned that the plurality of partial-span inlet guide vanes 100 comprises approximately ten to approximately fifty partial-span inlet guide vanes 100. In yet another exemplary embodiment, it is envisioned that the plurality of partial-span inlet guide vanes 100 comprises approximately twenty and approximately forty-five partial-span inlet guide vanes 100. Furthermore, in the illustrated embodiment, each of the plurality of partial-span inlet guide vanes 100 is substantially uniformly (e.g., equidistantly) spaced along the circumferential direction C. More specifically, each of the plurality of partial span inlet guide vanes 100 defines a circumferential spacing 118 with the adjacent partial span inlet guide vane 100, and the circumferential spacing 118 between each adjacent partial span inlet guide vane 100 is substantially equal.

[0053] Although not depicted, in some exemplary embodiments, the number of partial span inlet guide vanes 100 may be substantially equal to the number of fans 38 of the turbofan engine 10. Figure 1 ) fan blades 40 ( Figure 1 The number of partial span inlet guide vanes 100 may be greater than the number of fan blades 40 of fan 38 of turbofan engine 10, or alternatively, may be less than the number of fan blades 40 of fan 38 of turbofan engine 10.

[0054] Furthermore, it should be understood that in other exemplary embodiments, the turbofan engine 10 may include any other suitable number of partial span inlet guide vanes 100 and / or the circumferential spacing 118 of the partial span inlet guide vanes 100. For example, reference is now briefly made to... Figure 4 An axial view of the inlet 60 of a turbofan engine 10 according to another exemplary embodiment of the present disclosure is provided. For Figure 4 In one embodiment, the turbofan engine 10 includes fewer than twenty component span inlet guide vanes 100. More specifically, for Figure 4 In one embodiment, the turbofan engine 10 includes at least eight partial-span inlet guide vanes 100, or more specifically, exactly eight partial-span inlet guide vanes 100. Additionally, for Figure 4In this embodiment, the plurality of partial span inlet guide vanes 100 are not substantially uniformly spaced along the circumferential direction C. For example, at least some of the plurality of partial span inlet guide vanes 100 define a first circumferential spacing 118A, while other partial span inlet guide vanes 100 define a second circumferential spacing 118B. For the illustrated embodiment, the first circumferential spacing 118A is at least about 20 percent larger than the second circumferential spacing 118B, for example, at least about 25 percent, for example, at least about 30 percent, for example, up to about 200 percent. It is worth noting that the circumferential spacing 118 refers to the average circumferential spacing between adjacent partial span inlet guide vanes 100. The non-uniform circumferential spacing can, for example, offset the structure upstream of the partial span inlet guide vanes 100.

[0055] Return to reference Figure 3 The outer nacelle 50 defines a radius NR. In the illustrated embodiment, multiple partial span inlet guide vanes 100 are angled (e.g., tilted) relative to the radius NR of the outer nacelle 50, i.e., at a first angle A1.

[0056] In this way, multiple partial span inlet guide vanes 100 are configured to guide incoming objects toward the turbofan engine 10. Figure 1 The outer radial portion of the turbine fan engine 100 is configured to guide incoming objects away from the core airflow path 37 of the turbine fan engine 10. Figure 1 And toward the bypass airflow channel 56 ( Figure 1 This provides a deflection mechanism that helps to draw objects into the turbofan engine 10. Figure 1 The outer radial portion of the object minimizes the chance of it traveling to the core of the turbofan engine 10.

[0057] Furthermore, in this manner, multiple partial span inlet guide vanes 100 are also configured to provide pre-swirling flow through inlet 60 of outer nacelle 50 (in fan 38). Figure 1 ) multiple fan blades 40 ( Figure 1 The upstream airflow of 58 ( Figure 1 As discussed herein, the pre-swirling flow provided by the airflow 58 through the inlet 60 of the nacelle 50 before this airflow 58 reaches the multiple fan blades 40 of the fan 38 can reduce separation losses and / or shock wave losses, allowing the fan 38 to operate at the relatively high fan tip speeds described above with minimal efficiency losses. Furthermore, in this way, the multiple partial-span inlet guide vanes 100 are also configured to minimize flutter and maintain laminar airflow through the partial-span inlet guide vanes 100 and minimize turbulence in the inlet 60.

[0058] In some exemplary embodiments, the first angle A1 is between approximately 2 degrees and approximately 45 degrees. In other exemplary embodiments, the first angle A1 is envisioned to be within other ranges for a particular application.

[0059] exist Figure 3 In the exemplary embodiment shown, a plurality of partial span inlet guide vanes 100 are in a clockwise direction CW (i.e., with respect to fan blades 40). Figure 2 (Rotate in the same direction) relative to the radius NR of the outer cabin 50 at a first angle A1.

[0060] In one exemplary embodiment, the plurality of partial span inlet guide vanes 100 each form the same first angle A1 relative to the radius NR of the outer nacelle 50. In other exemplary embodiments, the plurality of partial span inlet guide vanes 100 form different first angles A1 relative to the radius NR of the outer nacelle 50, which will be described in more detail below.

[0061] Now for reference Figure 5 Provided according to another exemplary embodiment Figure 1 and Figure 2 Axial view of the inlet 60 of the turbofan engine 10. (Reference) Figure 5 In another exemplary embodiment, a plurality of partial span inlet guide vanes 100 are in the counterclockwise direction CCW (i.e., with the fan blades 40). Figure 2 (Rotate in the opposite direction) relative to the radius NR of the outer cabin 50 at a first angle A1.

[0062] Now back Figure 2 As described above, each of the multiple partial-span inlet guide vanes 100 is configured to provide pre-swirling airflow 58 through the inlet 60 of the nacelle 50 (upstream of the multiple fan blades 40 of the fan 38). As described above, the pre-swirling airflow 58 provided by the inlet 60 of the nacelle 50 before the airflow 58 reaches the multiple fan blades 40 of the fan 38 can reduce separation losses and / or shock wave losses, allowing the fan 38 to operate at the relatively high fan tip speeds described above with minimal efficiency loss.

[0063] For example, first refer to Figure 6 It provides such as Figure 2Line 6-6 shows a cross-sectional view of a partial span inlet guide vane 100 along the span of the partial span inlet guide vane 100. As shown, the partial span inlet guide vane 100 is generally constructed as an airfoil having a pressure side 120 and an opposing suction side 122, and extending along an arc 124 between the leading edge 108 and the trailing edge 110. Furthermore, the partial span inlet guide vane 100 defines a chord 126 extending directly from the leading edge 108 to the trailing edge 110. The chord 126 of the partial span inlet guide vane 100 is relative to the longitudinal axis 12 of the outer nacelle 50. Figure 2 An angle (e.g., torsion), i.e., a second angle or angle of attack 128. For example, the chord 126 is perpendicular to the entrance 60 through the cabin 50. Figure 2 The airflow direction 129 of the airflow 58 defines a second angle or angle of attack 128. It is noteworthy that, for the illustrated embodiment, the airflow direction 129 is substantially parallel to the axial direction A and longitudinal axis 12 of the outer nacelle 50 of the turbofan engine 10. For the illustrated embodiment, the angle of attack 128 at the location depicted along the span 106 of the partial span inlet guide vane 100 is at least approximately five degrees and up to approximately thirty-five degrees. For example, in some embodiments, the angle of attack 128 at the location depicted along the span 106 of the partial span inlet guide vane 100 can be between approximately ten degrees and approximately thirty degrees, for example, between approximately fifteen degrees and approximately twenty-five degrees.

[0064] Furthermore, along the span 106 of the guide vane 100 at the partial span inlet... Figure 2 At the location depicted, the partial-span inlet guide vane 100 defines a local swirl angle 130 at its trailing edge 110. As used herein, the "swirl angle" at the trailing edge 110 of the partial-span inlet guide vane 100 refers to the angle of flow through the nacelle 50 ( Figure 2 ) entrance 60 ( Figure 2 The angle between the airflow direction 129 of the airflow 58 and the reference line 132 defined by the trailing edge segment of the pressure side 120 of the partial span inlet guide vane 100. More specifically, the reference line 132 is defined by the last twenty percent of the pressure side 120 measured along the chord 126. It is worth noting that when the last twenty percent of the pressure side 120 defines a curve, the reference line 132 can be a linear average fit to such a curve (e.g., using the least mean square).

[0065] Furthermore, it should be understood that the maximum swirl angle 130° refers to the span 106° along the partial span inlet guide vane 100. Figure 2 The maximum swirl angle is 130°. For the illustrated embodiment, the maximum swirl angle 130 is limited to the radially outer end 102 of the partial span inlet guide vane 100. Figure 2Near (e.g., at the outer 100th of the span 106 of the partial span inlet guide vane 100), such as Figure 6 The cross-section depicted is shown in the figure. For the illustrated embodiment, the maximum swirl angle 130 of each partial span inlet guide vane 100 at the trailing edge 110 is between approximately five degrees and approximately thirty-five degrees. For example, in some exemplary embodiments, the maximum swirl angle 130 of each partial span inlet guide vane 100 at the trailing edge 110 may be between twelve degrees and twenty-five degrees.

[0066] Furthermore, it should be understood that, for Figure 2 In this embodiment, a local swirl angle 130 is provided from the radial inner end 104 of the guide vane 100 at the inlet of each partial span. Figure 2 ) towards the radial outer end 102 ( Figure 2 ) Add. For example, now also refer to Figure 7 It provides such as Figure 2 The partial span of the inlet guide vane 100 shown in line 7-7 is from... Figure 6 A cross-sectional view at a radially inward location observed in the cross-section. (See image.) Figure 7 As shown and as described above, the partial span inlet guide vane 100 defines a pressure side 120, a suction side 122, a leading edge 108, a trailing edge 110, an arc 124, and a chord 126. Furthermore, the airflow direction 129, formed by the chord 126 and the airflow 58 passing through the inlet 60 of the nacelle 50, is along... Figure 7 The second angle or angle of attack 128, defined at the position of span 106 shown, is less than along the... Figure 6 The angle of attack 128 at the position of span 106 depicted in the diagram (e.g., it may be at least about 20 percent smaller, for example at least about 50 percent smaller, for example at most about 100 percent smaller). Furthermore, the partial span inlet guide vane 100 defines a local swirl angle 130 at its trailing edge 110 near the inner end 104 at the position of span 106 along the partial span inlet guide vane 100, as... Figure 7 As shown. As described above, the local swirl angle 130 increases from the radially inner end 104 to the radially outer end 102 of each partial span inlet guide vane 100. Therefore, the local swirl angle 130 near the outer end 102 (see...) Figure 6 The local swirl angle 130° is greater than that near the radial inner end 104 (see...). Figure 7 For example, 10 percent of the radial interior of span 106. For example, the local swirl angle 130 may be close to zero degrees at the radial interior end 104 (e.g., less than about five degrees, for example less than about two degrees).

[0067] It is worth noting that including a partial span inlet guide vane 100 with this configuration can reduce the radial inner end 104 of each corresponding partial span inlet guide vane 100. Figure 2Turbulent flow at ) . Furthermore, such a configuration can be implemented in fan 38 ( Figure 2 ) multiple fan blades 40 ( Figure 2 The desired amount of pre-swirling flow is provided at the radially outer end of the turbine fan 10 (where the fan blade 40 rotates at its maximum speed) to provide a desired reduction in flow separation and / or shock wave losses, otherwise in the turbofan engine 10. Figure 2 During operation, flow separation and / or shock wave loss may occur due to the relatively high speed of the multiple fan blades 40 at the fan tip.

[0068] Now for reference Figure 8 Provided according to another exemplary embodiment Figure 1 and Figure 2 Axial view of the inlet 60 of the turbofan engine 10. (Reference) Figure 8 In another exemplary embodiment, multiple partial span inlet guide vanes 100 are at different first angles A1 relative to the radius NR of the outer nacelle 50.

[0069] The outer nacelle 50 includes a top 210, a bottom 212, a first side 214, and a second side 216. In an exemplary embodiment, a first portion of the partial span inlet guide vane 100, such as the top 210, forms a first angle A1 relative to the radius NR of the outer nacelle 50. For example, the partial span inlet guide vane 100 forms a first angle A1 of five or seven degrees relative to the radius NR of the outer nacelle 50 at the top 210. Furthermore, a second portion of the partial span inlet guide vane 100, such as the first side 214, forms a different angle relative to the radius NR of the outer nacelle 50. For example, the partial span inlet guide vane 100 forms a first angle A1 of ten or fifteen degrees relative to the radius NR of the outer nacelle 50 at the first side 214. In such an exemplary embodiment, multiple partial span inlet guide vanes 100 form different first angles A1 relative to the radius NR of the outer nacelle 50 along the circumferential direction C.

[0070] In such an exemplary embodiment, circumferential variations in the tilt angle, such as a circumferential variation of a first angle A1 relative to the radius NR of the outer nacelle 50, can address numerous issues, including crosswinds, high angle-of-attack maneuvers such as takeoff, and engine mounting on one or the other side of the aircraft. For example, crosswinds are more likely to affect the 3 o'clock or 9 o'clock positions on the engine, such as the second side 216 and the first side 214, which could make the 3 / 9 o'clock position on the engine require a different tilt angle than the 6 / 12 o'clock position (e.g., bottom 212 and top 210). Furthermore, mounting on one or the other side of the aircraft may make the crosswind effect more pronounced on the side of the engine farther from the fuselage. Similarly, high angles of attack may make different tilt angles at the 6 / 12 o'clock position (e.g., bottom 212 and top 210) desirable. For these reasons, it is envisioned that the first angle A1 relative to the radius NR of the outer cabin 50 can vary for a specific application and can be different at the top 210, bottom 212, first side 214 and / or second side 216 of the outer cabin 50.

[0071] Now for reference Figure 9 Provided according to another exemplary embodiment Figure 1 and Figure 2 Axial view of the inlet 60 of the turbofan engine 10. (Reference) Figure 9 In another exemplary embodiment, multiple partial span inlet guide vanes 100 are at different first angles A1 relative to the radius NR of the outer nacelle 50.

[0072] The outer nacelle 50 includes a top 210, a bottom 212, a first side 214, and a second side 216. In an exemplary embodiment, the partial span inlet guide vane 100 forms different first angles A1 with respect to the radius NR of the outer nacelle 50 at the top 210 and bottom 212. For example, the top 210 of the partial span inlet guide vane 100 forms a first angle A1 with respect to the radius NR of the outer nacelle 50. For example, the partial span inlet guide vane 100 forms a first angle A1 of five degrees or seven degrees with respect to the radius NR of the outer nacelle 50 at the top 210. Furthermore, the bottom 212 of the partial span inlet guide vane 100 forms a different angle with respect to the radius NR of the outer nacelle 50. For example, the partial span inlet guide vane 100 forms a first angle A1 of ten degrees with respect to the radius NR of the outer nacelle 50 at the bottom 212. In such an exemplary embodiment, multiple partial span inlet guide vanes 100 are at different first angles A1 relative to the radius NR of the outer nacelle 50 at the top 210 and bottom 212.

[0073] In such an exemplary embodiment, circumferential variations in the tilt angle, such as a circumferential variation of a first angle A1 relative to the radius NR of the outer nacelle 50, can address numerous issues, including crosswinds, high angle-of-attack maneuvers such as takeoff, and engine mounting on one or the other side of the aircraft. For example, crosswinds are more likely to affect the 3 o'clock or 9 o'clock positions on the engine, such as the second side 216 and the first side 214, which could make the 3 / 9 o'clock position on the engine require a different tilt angle than the 6 / 12 o'clock position (e.g., bottom 212 and top 210). Furthermore, mounting on one or the other side of the aircraft may make the crosswind effect more pronounced on the side of the engine farther from the fuselage. Similarly, high angles of attack may make different tilt angles at the 6 / 12 o'clock position (e.g., bottom 212 and top 210) desirable. For these reasons, it is envisioned that the first angle A1 relative to the radius NR of the outer cabin 50 can vary for a specific application and can be different at the top 210, bottom 212, first side 214 and / or second side 216 of the outer cabin 50.

[0074] Now for reference Figure 10 Provided according to another exemplary embodiment Figure 1 and Figure 2 Axial view of the inlet 60 of the turbofan engine 10. (Reference) Figure 10 In another exemplary embodiment, one of the partial span inlet guide vanes 100 is at a different angle relative to the radius NR of the outer nacelle 50 at different portions of the partial span inlet guide vane 100.

[0075] For example, the partial span inlet guide vane 100 forms a first angle A1 with respect to the radius NR of the outer nacelle 50 at a first position 250, and a second angle A2 with respect to the radius NR of the outer nacelle 50 at a second position 252. In such an embodiment, the first angle A1 is different from the second angle A2. For example, in Figure 10 In the embodiment shown, the first angle A1 is greater than the second angle A2.

[0076] In such an exemplary embodiment, when you approach / move away from the wall 52 of the outer cabin 50 ( Figure 2 When changing the bottom of the guide vane 100 from the partial span inlet (e.g., the outer end 102), the guide vane 100 is changed. Figure 2 ()) to the tip of the partial span inlet guide vane 100 (e.g., inner end 104) Figure 2 The tilt angle (e.g., first angle A1 and second angle A2) can resolve different degrees of turbulence caused by boundary layer effects. When you approach / move away from the axis 12 of engine 10 ( Figure 1At the same time, tilt angle and sweep angle can also be used to improve the swirl of incoming air and fan blades 40 ( Figure 2 Matching the changing linear velocity of the fan blades. (40) Figure 2 The linear velocity of the fan blades is greatest at the tip, while it is greatest at 40°. Figure 2 The slowest speed is at the root of the axis, even if the rotation speed is the same.

[0077] Now for reference Figure 11 Provided according to another exemplary embodiment Figure 1 and Figure 2 Axial view of the inlet 60 of the turbofan engine 10. (Reference) Figure 11 In another exemplary embodiment, one of the partial span inlet guide vanes 100 is at different angles relative to the radius NR of the outer nacelle 50 at different locations of the partial span inlet guide vane 100.

[0078] For example, the partial span inlet guide vane 100 forms a first angle A1 with respect to the radius NR of the outer nacelle 50 at a first position 250, and a second angle A2 with respect to the radius NR of the outer nacelle 50 at a second position 252. In such an embodiment, the first angle A1 is different from the second angle A2. For example, in Figure 11 In the embodiment shown, the first angle A1 is smaller than the second angle A2.

[0079] In such an exemplary embodiment, when you approach / move away from the wall 52 of the outer cabin 50 ( Figure 2 When changing the bottom of the guide vane 100 from the partial span inlet (e.g., the outer end 102), the guide vane 100 is changed. Figure 2 ()) to the tip of the partial span inlet guide vane 100 (e.g., inner end 104) Figure 2 The tilt angle (e.g., first angle A1 and second angle A2) can resolve different degrees of turbulence caused by boundary layer effects. When you approach / move away from the axis 12 of engine 10 ( Figure 1 At the same time, tilt angle and sweep angle can also be used to improve the swirl of incoming air and fan blades 40 ( Figure 2 Matching the changing linear velocity of the fan blades. (40) Figure 2 The linear velocity of the fan blades is greatest at the tip, while it is greatest at 40°. Figure 2 The slowest speed is at the root of the axis, even if the rotation speed is the same.

[0080] Other aspects of this disclosure are provided by the subject matter of the following clauses:

[0081] A turbofan engine includes: a fan including a plurality of fan blades; a turbine operatively coupled to the fan to drive the fan, the turbine including a compressor section, a combustion section and a turbine section in series flow sequence and together defining a core airflow path; a nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius and a longitudinal axis; and an inlet pre-swirl impeller located upstream of the plurality of fan blades and defining a chord, the inlet pre-swirl impeller coupled to the nacelle, wherein the inlet pre-swirl impeller forms a first angle relative to the radius of the nacelle, and wherein the chord of the inlet pre-swirl impeller forms a second angle relative to the longitudinal axis of the nacelle.

[0082] According to any of the preceding clauses of the turbofan engine, wherein the inlet pre-swirl impeller blades are at the first angle relative to the radius of the nacelle in a clockwise direction from the inlet of the nacelle.

[0083] According to any of the preceding clauses of the turbofan engine, wherein the inlet pre-swirl impeller blades are at the first angle relative to the radius of the nacelle in a counterclockwise direction from the inlet of the nacelle.

[0084] The turbofan engine according to any of the preceding clauses, wherein the first angle is between approximately 2 degrees and approximately 45 degrees.

[0085] According to any of the preceding clauses, the turbofan engine wherein the second angle is between approximately 5 degrees and approximately 35 degrees.

[0086] According to any of the preceding clauses of the turbofan engine, wherein the inlet pre-swirl impeller is one of a plurality of partial span inlet guide impellers extending from the nacelle upstream of the plurality of fan blades and behind the nacelle inlet.

[0087] According to any of the preceding clauses of the turbofan engine, each of the plurality of partial span inlet guide vanes forms the same first angle relative to the radius of the nacelle.

[0088] According to any of the preceding clauses of the turbofan engine, a first portion of each of the plurality of partial span inlet guide vanes forms a first angle relative to the radius of the nacelle, a second portion of each of the plurality of partial span inlet guide vanes forms a third angle relative to the radius of the nacelle, and wherein the first angle is different from the third angle.

[0089] According to any of the preceding clauses of the turbofan engine, wherein the nacelle includes a top, a bottom, a first side and a second side, wherein a first portion of each of the plurality of partial span inlet guide vanes forms a first angle at the top relative to the radius of the nacelle, wherein a second portion of each of the plurality of partial span inlet guide vanes forms a third angle at the bottom relative to the radius of the nacelle, and wherein the first angle is different from the third angle.

[0090] A nacelle assembly for a turbofan engine, the turbofan engine including a fan including a plurality of fan blades, the nacelle assembly including: a nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius and a longitudinal axis; and an inlet pre-swirl impeller located upstream of the plurality of fan blades and defining a chord, the inlet pre-swirl impeller being coupled to the nacelle, wherein the inlet pre-swirl impeller forms a first angle relative to the radius of the nacelle, and wherein the chord of the inlet pre-swirl impeller forms a second angle relative to the longitudinal axis of the nacelle.

[0091] According to any of the preceding clauses, the inlet pre-swirling impeller blades are arranged at the first angle relative to the radius of the nacelle in a clockwise direction from the nacelle inlet.

[0092] According to any of the preceding clauses, the inlet pre-swirling impeller blades are arranged at the first angle from the inlet of the nacelle in a counterclockwise direction relative to the radius of the nacelle.

[0093] According to any of the preceding clauses, the first angle is between approximately 2 degrees and approximately 45 degrees.

[0094] According to any of the preceding clauses, the second angle is between approximately 5 degrees and approximately 35 degrees.

[0095] According to any of the preceding clauses, the inlet pre-swirling impeller is one of a plurality of partial-span inlet guide impellers extending from the nacelle upstream of the plurality of fan blades and behind the nacelle inlet.

[0096] According to any of the preceding clauses, each of the plurality of partial span inlet guide vanes forms the same first angle relative to the radius of the nacelle.

[0097] According to any of the preceding clauses, in the nacelle assembly, a first portion of each of the plurality of partial span inlet guide vanes forms a first angle relative to the radius of the nacelle, a second portion of each of the plurality of partial span inlet guide vanes forms a third angle relative to the radius of the nacelle, and wherein the first angle is different from the third angle.

[0098] According to any of the preceding clauses, the nacelle includes a top, a bottom, a first side, and a second side, wherein a first portion of each of the plurality of partial span inlet guide vanes forms a first angle at the top relative to the radius of the nacelle, a second portion of each of the plurality of partial span inlet guide vanes forms a third angle at the bottom relative to the radius of the nacelle, and wherein the first angle is different from the third angle.

[0099] A nacelle assembly for a turbofan engine, the turbofan engine including a fan including a plurality of fan blades, the nacelle assembly including: a nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius; and an inlet pre-swirl impeller located upstream of the plurality of fan blades, the inlet pre-swirl impeller coupled to the nacelle, wherein the inlet pre-swirl impeller forms a first angle relative to the radius of the nacelle at a first position of the inlet pre-swirl impeller, wherein the inlet pre-swirl impeller forms a second angle relative to the radius of the nacelle at a second position of the inlet pre-swirl impeller, and wherein the first angle is different from the second angle.

[0100] According to any of the preceding clauses, the nacelle defines a longitudinal axis, the inlet pre-swirling impeller defines a chord, and the chord of the inlet pre-swirling impeller forms a third angle with respect to the longitudinal axis of the nacelle.

[0101] This written description uses examples to disclose this disclosure, including best practices, and also enables any person skilled in the art to practice this disclosure, including making and using any device or system and methods of making any combination. The patentable scope of this disclosure is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0102] While this disclosure is described as having an exemplary design, it can be further modified within its scope. Therefore, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Furthermore, this application is intended to cover any deviations from this disclosure within the scope of known or conventional practice in the art to which this disclosure pertains and within the scope of the appended claims.

Claims

1. A turbofan engine, characterized in that, include: The fan includes a plurality of fan blades; A turbine operatively coupled to the fan to drive the fan, the turbine comprising a compressor section, a combustion section and a turbine section in series flow sequence and together defining a core airflow path; A nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius and a longitudinal axis; and An inlet pre-swirling impeller is located upstream of the plurality of fan blades and defines a chord. The inlet pre-swirling impeller is coupled to the nacelle. The inlet pre-swirling impeller forms a first angle with respect to the radius of the nacelle, and the chord of the inlet pre-swirling impeller forms a second angle with respect to the longitudinal axis of the nacelle. The inlet pre-swirling impeller is one of a plurality of partial-span inlet guide impellers extending from the nacelle upstream of the plurality of fan blades and behind the inlet of the nacelle. The plurality of partial-span inlet guide impellers includes a first portion and a second portion of a partial-span inlet guide impeller. The first portion of the partial-span inlet guide impeller forms the first angle with respect to the radius of the nacelle, and the second portion of the partial-span inlet guide impeller forms a third angle with respect to the radius of the nacelle. The first angle is different from the third angle.

2. The turbofan engine according to claim 1, characterized in that, The inlet pre-swirling impeller blades are arranged at the first angle relative to the radius of the nacelle in a clockwise direction from the inlet of the nacelle.

3. The turbofan engine according to claim 1, characterized in that, The inlet pre-swirling impeller blades are arranged at the first angle relative to the radius of the nacelle in a counterclockwise direction from the inlet of the nacelle.

4. The turbofan engine according to claim 1, characterized in that, The first angle is between 2 degrees and 45 degrees.

5. The turbofan engine according to claim 1, characterized in that, The second angle is between 5 degrees and 35 degrees.

6. The turbofan engine according to claim 1, characterized in that, The inlet pre-swirling impeller blade includes an outer end and an inner end, wherein the inner end extends radially inward from the outer end, and wherein the second angle of the chord at the outer end is greater than the second angle of the chord at the inner end.

7. The turbofan engine according to claim 1, characterized in that, The cabin includes a top, a bottom, a first side, and a second side. The first portion of the partial span inlet guide vane is located at one of the top, the bottom, the first side, or the second side. The second portion of the partial span inlet guide vane is located at another location among the top, the bottom, the first side, or the second side.

8. The turbofan engine according to claim 1, characterized in that, The inlet pre-swirling impeller blade includes an outer end and an inner end, wherein the inner end extends radially inward from the outer end, and wherein the second angle of the chord increases from the inner end to the outer end.

9. A nacelle assembly for a turbofan engine, the turbofan engine including a fan, the fan including a plurality of fan blades, characterized in that, The cabin components include: A nacelle surrounds and at least partially encloses the fan, the nacelle defining a radius and a longitudinal axis; and An inlet pre-swirling impeller is located upstream of and defines a chord of the plurality of fan blades. The inlet pre-swirling impeller is coupled to the nacelle. The inlet pre-swirling impeller is one of a plurality of partial-span inlet guide impellers extending from the nacelle upstream of the plurality of fan blades and downstream of the nacelle inlet. The plurality of partial-span inlet guide impellers includes a first portion and a second portion of a partial-span inlet guide impeller. The first portion of a portion of the span-inlet guide vane forms a first angle with respect to the radius of the nacelle, and the second portion of a portion of the span-inlet guide vane forms a third angle with respect to the radius of the nacelle, wherein the first angle is different from the third angle. The chord of the inlet pre-swirling impeller blade forms a second angle with respect to the longitudinal axis of the nacelle.

10. The cabin assembly according to claim 9, characterized in that, The inlet pre-swirling impeller blades are arranged at the first angle relative to the radius of the nacelle in a clockwise direction from the inlet of the nacelle.

11. The cabin assembly according to claim 9, characterized in that, The inlet pre-swirling impeller blades are arranged at the first angle relative to the radius of the nacelle in a counterclockwise direction from the inlet of the nacelle.

12. The cabin assembly according to claim 9, characterized in that, The first angle is between 2 degrees and 45 degrees.

13. The cabin assembly according to claim 9, characterized in that, The second angle is between 5 degrees and 35 degrees.

14. The cabin assembly according to claim 9, characterized in that, The first angle, the second angle, and the third angle can vary.

15. The cabin assembly according to claim 9, characterized in that, The first angle is 5 degrees or 7 degrees.

16. The cabin assembly according to claim 15, characterized in that, The third angle is 10 degrees or 15 degrees.

17. The cabin assembly according to claim 14, characterized in that, The cabin includes a top, a bottom, a first side, and a second side. The first portion of the partial span inlet guide vane is located at one of the top, the bottom, the first side, or the second side. The second portion of the partial span inlet guide vane is located at another location among the top, the bottom, the first side, or the second side.

18. A turbofan engine, characterized in that, include: The fan includes multiple fan blades. A turbine operatively coupled to the fan to drive the fan, the turbine comprising a compressor section, a combustion section, and a turbine section in series flow sequence and together defining a core airflow path. A nacelle surrounding and at least partially enclosing the fan, the nacelle defining a radius and a longitudinal axis; and A plurality of partial span inlet guide vanes extend from the nacelle upstream of a plurality of fan blades and behind the nacelle inlet, wherein the plurality of partial span inlet guide vanes include a first portion and a second portion, wherein the first portion of the plurality of partial span inlet guide vanes forms a first angle with respect to the radius of the nacelle, and wherein the second portion of the plurality of partial span inlet guide vanes forms a third angle with respect to the radius of the nacelle, wherein the first angle is different from the third angle.

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