Patent Application
20250043686
A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-pressure and temperature exhaust gas flow. The high-pressure and temperature exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section may include low and high pressure compressors, and the turbine section may also include low and high pressure turbines.
Airfoils in the fan section or other sections of the engine may be formed of metallic alloys or composite material. Composite materials may include a layup of fiber plies that are impregnated with a matrix material. However, relative to the in-plane strength of the fiber plies, the composite material is weaker along the matrix-rich interface between the plies and may thus delaminate.
An airfoil according to an example of the present disclosure includes an airfoil wall formed of a fiber-reinforced composite material that has a layup structure that includes groups of unidirectional fiber tows. The groups are oriented at angles Θ(theta) relative to a reference orientation. The unidirectional fiber tows cross-over each other according to a sequence N1, N2, N3, . . . Ni, wherein N is a whole number that indicates which numerical group the unidirectional fiber tows are in and i is a whole number that indicates a sequential layup order of the unidirectional fiber tows. Each of the unidirectional fiber tows in the sequence starting at N2 crosses-over the unidirectional fiber tows of the other ones of the groups that have a lower value of i in the sequence.
In a further embodiment of the foregoing embodiment, the unidirectional fiber tows are in tapes.
In a further embodiment of any of the foregoing embodiments, N is at least 2 and i is at least 16.
In a further embodiment of any of the foregoing embodiments, the angles Θ(theta) are selected from the group consisting of 0/−30/+30/90, 0/−45/+45/90, 0/−60/+60/90, and the sequence is 11, 22, 33, . . . Ni.
In a further embodiment of any of the foregoing embodiments, each of the unidirectional fiber tows has a unique Ni in the sequence.
In a further embodiment of any of the foregoing embodiments, the fiber-reinforced composite material includes an organic matrix.
In a further embodiment of any of the foregoing embodiments, the airfoil wall is in a gas turbine engine article selected from the group consisting of a blade and a vane.
In a further embodiment of any of the foregoing embodiments, the airfoil is a fan blade in a fan section of a gas turbine engine that further includes a compressor section, a combustor in fluid communication with the compressor section, a turbine section in fluid communication with the combustor.
In a further embodiment of any of the foregoing embodiments, the unidirectional fiber tows are in tapes.
In a further embodiment of any of the foregoing embodiments, N is at least 2 and i is at least 16.
In a further embodiment of any of the foregoing embodiments, each of the fiber tapes has a unique Ni in the sequence.
In a further embodiment of any of the foregoing embodiments, N is 4, the angles Θ(theta) are selected from the group consisting of 0/−30/+30/90, 0/−45/+45/90, 0/−60/+60/90, and the sequence is 11, 22, 33, . . . Ni.
In a further embodiment of any of the foregoing embodiments, the fiber-reinforced composite material includes an organic matrix.
A method of fabricating an airfoil according to an example of the present disclosure includes forming an airfoil wall of a fiber-reinforced composite material by placing fiber tows on a surface at predetermined angles Θ(theta) relative to a reference orientation and according to a sequence N1, N2, N3, . . . Ni, to produce a layup structure, wherein N is a whole number that indicates a numerical group that the fiber tows are in and i is a whole number that indicates a sequential layup order that the fiber tows are placed onto the surface and each of the fiber tows in the sequence starting at N2 crosses-over the unidirectional fiber tows of the other ones of the groups that have a lower value of i in the sequence.
In a further embodiment of any of the foregoing embodiments, the unidirectional fiber tows are in preimpregnated tapes.
The present disclosure may include any one or more of the individual features disclosed above and/or below alone or in any combination thereof.
The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding elements. Terms such as “first” and “second” used herein are to differentiate that there are two architecturally distinct components or features. Furthermore, the terms “first” and “second” are interchangeable in that a first component or feature could alternatively be termed as the second component or feature, and vice versa.
The exemplary engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided, and the location of bearing systems 38 may be varied as appropriate to the application.
The low speed spool 30 generally includes an inner shaft 40 that interconnects, a first (or low) pressure compressor 44 and a first (or low) pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a speed change mechanism, which in exemplary gas turbine engine 20 is illustrated as a geared architecture 48 to drive a fan 42 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 50 that interconnects a second (or high) pressure compressor 52 and a second (or high) pressure turbine 54. A combustor 56 is arranged in the exemplary gas turbine 20 between the high pressure compressor 52 and the high pressure turbine 54. A mid-turbine frame 57 of the engine static structure 36 may be arranged generally between the high pressure turbine 54 and the low pressure turbine 46. The mid-turbine frame 57 further supports bearing systems 38 in the turbine section 28. The inner shaft 40 and the outer shaft 50 are concentric and rotate via bearing systems 38 about the engine central longitudinal axis A which is collinear with their longitudinal axes.
The core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, then expanded through the high pressure turbine 54 and low pressure turbine 46. The mid-turbine frame 57 includes airfoils 59 which are in the core airflow path C. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion. It will be appreciated that each of the positions of the fan section 22, compressor section 24, combustor section 26, turbine section 28, and fan drive gear system 48 may be varied. For example, gear system 48 may be located aft of the low pressure compressor, or aft of the combustor section 26 or even aft of turbine section 28, and fan 42 may be positioned forward or aft of the location of gear system 48.
The engine 20 in one example is a high-bypass geared aircraft engine. In a further example, the engine 20 bypass ratio is greater than about six (6), with an example embodiment being greater than about ten (10), and can be less than or equal to about 18.0, or more narrowly can be less than or equal to 16.0. The geared architecture 48 is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3. The gear reduction ratio may be less than or equal to 4.0. The low pressure turbine 46 has a pressure ratio that is greater than about five. The low pressure turbine pressure ratio can be less than or equal to 13.0, or more narrowly less than or equal to 12.0. In one disclosed embodiment, the engine 20 bypass ratio is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor 44, and the low pressure turbine 46 has a pressure ratio that is greater than about five 5:1. Low pressure turbine 46 pressure ratio is pressure measured prior to an inlet of low pressure turbine 46 as related to the pressure at the outlet of the low pressure turbine 46 prior to an exhaust nozzle. The geared architecture 48 may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about 2.3:1 and less than about 5:1. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including direct drive turbofans.
A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section 22 of the engine 20 is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet (10,668 meters). The flight condition of 0.8 Mach and 35,000 ft (10,668 meters), with the engine at its best fuel consumption—also known as “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. The engine parameters described above and those in this paragraph are measured at this condition unless otherwise specified. “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.45, or more narrowly greater than or equal to 1.25. “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram ° R)/(518.7° R)]0.5. The “Low corrected fan tip speed” as disclosed herein according to one non-limiting embodiment is less than about 1150.0 ft/second (350.5 meters/second), and can be greater than or equal to 1000.0 ft/second (304.8 meters/second).
As indicated earlier herein, relative to the in-plane strength of fiber plies, a laminated composite material is typically weaker along the matrix-rich interface between plies. The fiber tows 66 of the fiber-reinforced composite material 64, however, are provided in a sequenced layup structure that in essence eliminates such laminate interfaces.
Referring to
In the sequenced layup structure 70 the fiber tows 66 cross-over each other according to a sequence N1, N2, N3, . . . Ni, wherein N is a whole number representing the numerical group 1-4 that the unidirectional fiber tows are in and i is a whole number indicating a sequential layup order of the fiber tows 66 (i.e., the order in which the tows or tapes are placed when forming the layup). Each of the fiber tows 66 in the sequence starting at N2 crosses-over the fiber tows 66 of the other ones of the groups 1-4 that have a lower value of i in the sequence. As used herein, the term “crosses-over” or variations thereof are not intended to imply any particular crossing angle between tows or tapes, and the crossing angle will be dictated by the relative angles Θ(theta) of groups
For instance, in forming the sequenced layup structure 70, the fiber tows 66 (or alternatively preimpregnated fiber tapes) are individually placed into a substrate (e.g., a mandrel or mold surface) according to the sequence. A process known as automated fiber placement is used to conduct tow or tape placement. In such a process, a machine places each tow or tape in accordance with computer-aided design data that contains programmed information of the sequence. In the example shown (which in
In the illustrated example, each group 1-4 contains eight fiber tows (or tapes) and so the last tow 66 to be placed would be from group 4 and would designated 432 under the present nomenclature. In other words, as each tow 66 is placed onto the mold surface, it crosses-over the tows 66 of the other groups that were placed before it. Of course, in a given implementation each group may include fewer than eight tows 66 or, more likely, more than eight tows 66. Moreover, although demonstrated with four groups in this example, the sequenced layup structure 70 can alternatively have two groups, three groups, or more than four groups, such as up to nine groups (e.g., at 20° intervals).
As the fiber tows 66 of each group 1-4 are interleaved with the fiber tows 66 of the other groups, the resulting sequenced layup structure 70 in essence eliminates interlaminar interfaces that would otherwise be present if the groups 1-4 were instead provided as ply layers that are stacked one upon the next. Rather, there are local interfaces between adjacent overlapping fiber tows 66 (or tapes), but since the tows 66 are sequenced these local interfaces are at different “levels” in the sequence and are thus discontinuous from each other. In further examples, the thickness and/or width of the fiber tows or tapes are varied in order to modify the mechanical properties of the resulting composite article and create undulations that serve to interlock the tows/tapes together. For example, in the composite article a portion of the tows/tapes are of a first common thickness and width, and another portion of the tows/tapes are of a second common thickness and width that differs from the first common thickness and width. In this regard, thicker and wider tows/tapes billow into adjacent tow/tape levels and thereby limit lateral movement of the adjacent tows/tapes, thus serving to interlock tows/tapes between levels. In another example, the tapes/tows of one composite article of a first common thickness and width, and the tows/tapes are of a second composite article are of a second common thickness and width that differs from the first common thickness and width. In this regard, the properties of the composites can be varied by varying the selected thickness and width of the tows/tapes.
In the example of
A method of fabricating the blades 60 or other type of composite article of the fiber-reinforced material 64 includes placing the fiber tows (or tapes) 66 according to the sequence N1, N2, N3, . . . Ni, such as any of the sequences described above. The placing is conducted by automated fiber placement in which a machine places each tow or tape in accordance with computer-aided design data that contains programmed information of the sequence N1, N2, N3, . . . Ni. After placement of all of the tows or tapes 66, the preform may be further processed by the application of heat to cure the matrix material 68. Such heating may be conducted in a mold that has the design shape of the component being formed. If the tows or tapes are not preimpregnated with the matrix material 68 (or precursor thereof), the further processing may include infiltrating or depositing the matrix material in the fiber preform, such as by resin transfer molding, vacuum molding, or injection molding. As will be appreciated, the processing will depend to a large extent on the type of matrix material 68 being used.
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
