BACKGROUND OF THE INVENTION
The field of the disclosure relates generally to gas turbine engines and, more particularly, to a gas turbine engine assembly and methods of assembling the same.
At least some known gas turbine engines are split into two major assemblies, a fan case assembly and a core engine assembly, simplifying maintenance and shipping. The fan case assembly and core engine assembly are generally coupled together via an outlet guide vane assembly. To remove the core engine assembly from the fan case assembly, the core engine assembly is decoupled from the outlet guide vane assembly such that the core engine assembly can be shifted axially and removed from the fan case assembly and the outlet guide vane assembly. For this disassembly, the outside diameter of the core engine assembly is smaller than the inside diameter of the outlet guide vane assembly such that the core engine assembly can fit therebetween. When the fan case assembly including the outlet guide vane assembly is sized to fit over the core engine assembly, the diameter of the fan case assembly, including core cowl, fan case, and nacelle, is increased, thereby increasing overall engine weight and drag.
BRIEF DESCRIPTION OF THE INVENTION
In one aspect, a turbofan engine assembly is provided. The turbofan engine assembly includes a core gas turbine engine with a booster compressor having a radially outer diameter, a fan case assembly, and an outlet guide vane assembly. The outlet guide vane assembly includes a plurality of outlet guide vane segments spaced circumferentially about the core gas turbine engine. Each outlet guide vane segment of the plurality of outlet guide vane segments includes a radially inner fan hub frame flange configured to couple to the core gas turbine engine, a radially outer fan case flange configured to couple to the fan case assembly, and a plurality of outlet guide vanes extending therebetween. The radially inner diameter of the outlet guide vane assembly is smaller than the radially outer diameter of the booster compressor.

In another aspect, an aircraft including an engine is provided. The engine includes a core gas turbine engine with a booster compressor having a radially outer diameter, a fan case assembly, and an outlet guide vane assembly. The outlet guide vane assembly includes a plurality of outlet guide vane segments spaced circumferentially about the core gas turbine engine. Each outlet guide vane segment of the plurality of outlet guide vane segments includes a radially inner fan hub frame flange configured to couple to the core gas turbine engine, a radially outer fan case flange configured to couple to the fan case assembly, and a plurality of outlet guide vanes extending therebetween. The radially inner diameter of the outlet guide vane assembly is smaller than the radially outer diameter of the booster compressor.
In yet another aspect, a method of assembling a turbofan engine assembly is provided. The method includes coupling a core gas turbine engine including a booster compressor having a radially outer diameter to a fan case assembly via an outlet guide vane assembly. The outlet guide vane assembly includes a plurality of outlet guide vane segments spaced circumferentially about the core gas turbine engine. The outlet guide vane segments include a radially inner fan hub frame flange, a radially outer fan case flange, and a plurality of outlet guides vanes extending therebetween. The coupling a core gas turbine engine includes coupling the radially outer fan case flange to the fan case assembly, and coupling the radially inner fan hub fame flange to the core gas turbine engine, wherein a radially inner diameter of the outlet guide vane assembly is smaller than the radially outer diameter of the booster compressor.
BRIEF DESCRIPTION OF THE DRAWINGS OF THE INVENTION
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic illustration of an exemplary gas turbine engine in accordance with an example embodiment of the present disclosure.
FIG. 2 is a schematic side view of an exemplary outer guide vane segment from the turbofan engine shown in FIG. 1.
FIG. 3 is a perspective view of an exemplary turbofan engine shown in FIGS. 1 and 2.
FIG. 4 is a flow diagram of an exemplary embodiment of a method of assembling a turbofan engine assembly, such as the turbofan engine shown in FIGS. 1-3.
Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of this disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of this disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.
DETAILED DESCRIPTION
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.
"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about,"

"approximately," and "substantially," are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged; such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
Embodiments of the turbofan engine assembly described herein facilitate reducing the outer diameter of the fan case assembly and/or increasing fan diameter. Specifically, the turbofan engine assemblies and methods described herein allow for the outer diameter of the core gas turbine engine to be smaller than the inner diameter of the outlet guide vane assembly. The outlet guide vane assembly includes a plurality of outlet guide vane segments spaced circumferentially about the core gas turbine engine. Each outlet guide vane segment includes a radially inner fan hub frame flange configured to couple to the core gas turbine engine, a radially outer fan case flange configured to couple to the fan case assembly, and a plurality of outlet guide vanes extending therebetween. The core gas turbine engine is removable from the fan case assembly by decoupling at least one outlet guide vane segment from the core gas turbine engine and/or fan case assembly and shifting the core gas turbine engine in a radial direction before moving in an axial direction. Disassembling the turbofan engine assembly as described herein provides for maintaining the time requirement to remove the turbofan engine assembly to one working shift and enabling conventional shipping means for the core gas engine turbine assembly. Additionally, the turbofan engine assembly described herein offers advantages that include, without limitation, reducing the outer diameter of the fan case assembly, reducing overall engine weight, reducing nacelle drag, reducing time to split core gas turbine engine and fan case assembly, increasing fan diameter and air flow, and increasing booster compressor outer diameter.
FIG. 1 is a schematic cross-sectional view of a gas turbine engine in accordance with an exemplary embodiment of the present disclosure. In the exemplary

embodiment, the gas turbine engine is a high-bypass turbofan jet engine 110, referred to herein as "turbofan engine 110." As shown in FIG. 1, turbofan engine 110 defines an axial direction A (extending parallel to a longitudinal centerline 112 provided for reference) and a radial direction R (extending perpendicular to longitudinal centerline 112). In general, turbofan engine 110 includes a fan case assembly 114 and a core gas turbine engine 116 disposed downstream from fan case assembly 114.
Core gas turbine engine 116 includes a substantially tubular outer casing 118 that defines an annular inlet 120. Outer casing 118 encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor 122 and a high pressure (HP) compressor 124; a combustion section 126; a turbine section including a high pressure (HP) turbine 128 and a low pressure (LP) turbine 130; and a jet exhaust nozzle section 132. A high pressure (HP) shaft or spool 134 drivingly connects HP turbine 128 to HP compressor 124. A low pressure (LP) shaft or spool 136 drivingly connects LP turbine 130 to booster compressor 122. The compressor section, combustion section 126, turbine section, and nozzle section 132 together define a core air flow path 137.
In the exemplary embodiment, fan case assembly 114 includes a fan 138 having a plurality of fan blades 140 coupled to a disk 142 in a spaced apart manner. As depicted, fan blades 140 extend outwardly from disk 142 generally along radial direction R. Fan blades 140 and disk 142 are together rotatable about longitudinal centerline 112 by LP shaft 136.
Referring still to the exemplary embodiment of FIG. 1, disk 142 is covered by rotatable front hub 144 aerodynamically contoured to promote an airflow through plurality of fan blades 140. Additionally, exemplary fan case assembly 114 includes an annular fan casing or outer nacelle 150 that circumferentially surrounds fan 138 and/or at least a portion of core gas turbine engine 116. It should be appreciated that nacelle 150 may be configured to be supported relative to core gas turbine engine 116 by an outlet guide vane assembly 152. Moreover, a

downstream section 154 of nacelle 150 may extend over an outer portion of core gas turbine engine 116 so as to define a bypass airflow passage 156 therebetween.
Moreover, in the exemplary embodiment, outlet guide vane assembly 152 includes a plurality of outlet guide vane segments 149 spaced circumferentially about core gas turbine engine 116. Each outlet guide vane segment 149 includes a plurality of outlet guide vanes 151 that are removable and extend between a radially inner fan hub frame flange 153 and a radially outer fan case flange 155. Radially inner fan hub frame flange 153 is removably coupled to core gas turbine engine 116 via a fan frame hub 157. Specifically, radially inner fan hub frame flange 153 is removably coupled to fan frame hub 157 between booster compressor 122 and HP compressor 124. Additionally, each outlet guide vane segment 149 includes radially outer fan case flange 155 that is removably coupled to fan case assembly 114. Specifically, radially outer fan case flange 155 is removably coupled to outer nacelle 150. Generally, outlet guide vane assembly 152 facilitates fan case assembly 114 removably coupling to core gas turbine engine 116 such that at least a portion of core gas turbine 116 engine is circumferentially surround by fan case assembly 114 as illustrated in FIG. 1.
During operation of turbofan engine 110, a volume of air 158 enters turbofan 110 through an associated inlet 160 of nacelle 150 and/or fan case assembly 114. As air 158 passes across fan blades 140, a first portion of air 158 as indicated by arrows 162 is directed or routed into bypass airflow passage 156 and a second portion of air 158 as indicated by arrows 164 is directed or routed into core air flow path 137, or more specifically into booster compressor 122. The ratio between first portion of air 162 and second portion of air 164 is commonly known as a bypass ratio. The pressure of second portion of air 164 is then increased as it is routed through HP compressor 124 and into combustion section 126, where it is mixed with fuel and burned to provide combustion gases 166.
Combustion gases 166 are routed through HP turbine 128 where a portion of thermal and/or kinetic energy from combustion gases 166 is extracted via

sequential stages of HP turbine stator vanes 168 that are coupled to outer casing 118 and HP turbine rotor blades 170 that are coupled to HP shaft or spool 134, thus causing HP shaft or spool 134 to rotate, thereby supporting operation of HP compressor 124. Combustion gases 166 are then routed through LP turbine 130 where a second portion of thermal and kinetic energy is extracted from combustion gasses 166 via sequential stages of LP turbine stator vanes 172 that are coupled to outer casing 118 and LP turbine rotor blades 174 that are coupled to LP shaft or spool 136, thus causing LP shaft or spool 136 to rotate, thereby supporting operation of booster compressor 122 and/or rotation of fan 138. Combustion gases 166 are subsequently routed through jet exhaust nozzle section 132 of core gas turbine engine 116 to provide propulsive thrust. Simultaneously, the pressure of first portion of air 162 is substantially increased as first portion of air 162 is routed through bypass airflow passage 156, including through outlet guide vane assembly 152 wherein radially inner fan hub frame flange 153 defines the inner flowpath and radially outer fan case flange 155 defines the outer flowpath through outlet guide vanes 151, before it is exhausted from a fan nozzle exhaust section 176 of turbofan 110, also providing propulsive thrust. HP turbine 128, LP turbine 130, and jet exhaust nozzle section 132 at least partially define a hot gas path 178 for routing combustion gases 166 through core gas turbine engine 116.
It should be appreciated, however, that exemplary turbofan engine 110 depicted in FIG. 1 is by way of example only, and that in other exemplary embodiments, turbofan engine 110 may have any other suitable configuration. It should also be appreciated, that in still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine. For example, in other exemplary embodiments, aspects of the present disclosure may be incorporated into, e.g., a turboprop engine.
FIG. 2 is a schematic side view of outlet guide vane segment 149 from turbofan engine 110 (shown in FIG. 1). In the exemplary embodiment, outlet guide vane segment 149 is coupled to a booster compressor casing 179 aft of booster

compressor 122. Specifically, radially inner fan hub frame flange 153 is removably coupled via a plurality of bolts 180 and bolt flanges 182 spaced circumferentially about core gas turbine engine 116 to a structural support member, such as fan frame hub 157, which is coupled to booster compressor casing 179. Additionally, outlet guide vane segment 149 via radially outer fan case flange 155 is removably coupled to fan case assembly 114 via a similar plurality of bolts 180 and bolt flanges 182 spaced circumferentially about core gas turbine engine 116. In alternative embodiments, outlet guide vane segment 149 is coupled to core gas turbine engine 116 and/or fan case assembly 114 using any other connection method that enables turbofan engine 110 to be assembled as described herein.
In the exemplary embodiment, booster compressor 122 has a radially outer diameter defined by a radius 186 from longitudinal centerline 112. Additionally, outlet guide vane assembly 152 has a radially inner diameter defined by a radius 188 from longitudinal centerline 112. Fan case assembly 114 is removably coupled to core gas turbine engine 116 via outlet guide vane assembly 152 such that the radially inner diameter of outlet guide vane assembly 152 is smaller than the radially outer diameter of booster compressor 122. When the radially inner diameter of outlet guide vane assembly 152 is reduced the diameter of fan case assembly 114 and outer nacelle 150 may be reduced such that turbofan engine 110 weight and drag is lowered. Additionally, when the radially inner diameter of outlet guide vane assembly 152 is reduced turbofan engine 110 may receive a larger diameter fan 138 such that air flow 158 therethrough is increased without increasing the diameter of outer nacelle 150. Moreover, when the radially outer diameter of booster compressor 122 is not linked to the radially inner diameter of outlet guide vane assembly 152, turbofan engine 110 may receive booster compressor 122 with a larger radially outer diameter such that engine power is increased.
FIG. 3 is a perspective view of an exemplary turbofan engine 110 including fan case assembly 114, core gas turbine engine 116, and outlet guide vane assembly

152 (as shown in FIGS. 1 and 2). In the exemplary embodiment outlet guide vane assembly 152 includes the plurality of outlet guide vane segments 149 such as a first outlet guide vane segment 190 and a second outlet guide vane segment 192. First outlet guide vane segment 190 is split from second outlet guide vane segment 192 at a radially inner fan hub frame flange split line 194 and a radially outer fan case flange split line 196. It should be appreciated that outlet guide vane assembly 152 is shown as first and second outlet guide vane segments 190 and 192, outlet guide vane assembly 152 may be split into any number of segments that enables turbofan engine 110 to function as described herein.
In the exemplary embodiment, turbofan engine 110 includes two assemblies, fan case assembly 114 and core gas turbine engine 116, simplifying maintenance and shipping. For example, to separate fan case assembly 114 from core gas turbine engine 116 for maintenance, outlet guide van assembly 152 is split into first and second outlet guide vane segments 190 and 192. First outlet guide vane segment 190 is decoupled from core gas turbine engine 116 at radially inner fan hub frame flange 153. Second outlet guide vane segment 192 is decoupled from fan case assembly 114 at radially outer fan case flange 155. Core gas turbine engine 116 is shifted in a radial direction away from the remaining first outlet guide vane segment 190. Core gas turbine engine 116 is then shifted radially to clear the radially inner diameter of first outlet guide vane segment 190 that is smaller than the radially outer diameter of booster compressor 122. Core gas turbine engine 116 with second outlet guide vane segment 192 is removed from fan case assembly 114 with first outlet guide vane segment 190 in axial direction A (shown in FIG. 1). In some embodiments second outlet guide vane segment 192 may also be decoupled and removed from core gas turbine engine 116 at radially inner fan hub frame flange 153 such that outlet guide vane assembly 152 is not coupled to either fan case assembly 114 nor core gas turbine engine 116.
Conversely, to assemble turbofan engine 110, core gas turbine engine 116 with second outlet guide vane segment 192 is inserted in axial direction A (shown in FIG. 1) into fan case assembly 114 with first outlet guide vane segment 190. Core