Patent Application
20180038386
This disclosure relates to gas turbine engines, and more particularly to fan blades for gas turbine engines.
A typical gas turbine engine includes a fan section including a fan rotor. The fan rotor includes a fan hub, with a plurality of fan blades secured to the fan hub and extending radially outwardly from the fan hub. In some gas turbine engine fans, the fan blades are hollow, or have cavities extending through the fan blades to reduce weight of the fan blades and/or improve operational performance of the fan blades, when compared to a solid fan blade, having no cavities. The hollow fan blades are typically formed from a metal material, such as titanium, and are typically fabricated by diffusion bonding a relatively thin cover onto a blade body with hollow cavities. This manufacturing process requires extensive investment in capital equipment and often produces dimensionally non-conforming parts. Alternative processes have been explored, one of which consists of adhesively bonding the cover onto the blade body. Lighter weight cover materials, such as carbon/epoxy composite, have been considered as well. Manufacturing trials for this configuration indicated that the elevated cure temperature of the epoxy film adhesive (approximately 250° F.), combined with the coefficient of thermal expansion mismatch between the titanium body and the composite cover, results in a distorted blade shape at room temperature. This distortion would be more pronounced at lower temperatures where the difference between the stress-free temperature (200 F-250° F.) and the coldest expected operating temperature (−65 F) is even greater.
In one embodiment, a fan blade assembly for a gas turbine engine includes a blade body, a blade cover secured to the blade body and an adhesive layer to secure the blade cover to the blade body, the adhesive layer configured to set at ambient temperature.
Additionally or alternatively, in this or other embodiments the adhesive layer includes a urethane, silicone, epoxy or polysulfide material.
Additionally or alternatively, in this or other embodiments the blade cover and the blade body define one or more blade channels in the fan blade assembly.
Additionally or alternatively, in this or other embodiments the blade body includes one or more ribs.
Additionally or alternatively, in this or other embodiments the one or more blade channels extend in a substantially radial direction.
Additionally or alternatively, in this or other embodiments the fan blade assembly is configured for an operating temperature between −65 and 200 degrees Fahrenheit.
Additionally or alternatively, in this or other embodiments the blade body is formed from a first material and the blade cover is formed from a second material different from the first material.
Additionally or alternatively, in this or other embodiments the blade body is formed from a metal material and the blade cover is formed from a carbon fiber reinforced composite material.
In another embodiment, a method of forming a fan blade assembly for a gas turbine engine includes forming a blade body, forming a blade cover separate from the blade body, and adhering the blade cover to the blade body via an adhesive layer located between the blade body and the blade cover, the adhesive layer configured to set at ambient temperature.
Additionally or alternatively, in this or other embodiments the adhesive layer includes a urethane, silicone, epoxy or polysulfide material.
Additionally or alternatively, in this or other embodiments one or more blade channels are defined between the blade cover and the blade body.
Additionally or alternatively, in this or other embodiments one or more ribs are formed in the blade body.
Additionally or alternatively, in this or other embodiments the one or more blade channels extend in a substantially radial direction.
Additionally or alternatively, in this or other embodiments the fan blade assembly is configured for an operating temperature between −65 and 350 degrees Fahrenheit.
Additionally or alternatively, in this or other embodiments the blade body is formed from a first material and the blade cover is formed from a second material different from the first material.
Additionally or alternatively, in this or other embodiments the blade body is formed from a metal material and the blade cover is formed from a carbon fiber reinforced composite material.
In yet another embodiment, a fan assembly for a gas turbine engine includes a fan hub and a plurality of fan blades extending radially outwardly from the fan hub. At least one fan blade of the plurality of fan blades includes a blade body, a blade cover secured to the blade body, and an adhesive layer to secure the blade cover to the blade body. The adhesive layer is configured to set at ambient temperature.
Additionally or alternatively, in this or other embodiments the adhesive layer includes a urethane, silicone, epoxy or polysulfide material.
Additionally or alternatively, in this or other embodiments the blade body is formed from a first material and the blade cover is formed from a second material different from the first material.
Additionally or alternatively, in this or other embodiments the blade body is formed from a metal material and the blade cover is formed from a carbon fiber composite material.
The subject matter which is regarded as the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The gas turbine engine 10 further comprises a turbine section 20 for extracting energy from the combustion gases. Fuel is injected into the combustor 18 of the gas turbine engine 10 for mixing with the compressed air from the compressor 16 and ignition of the resultant mixture. The fan 12, compressor 16, combustor 18, and turbine 20 are typically all concentric about a common central longitudinal axis X of the gas turbine engine 10.
The gas turbine engine 10 may further comprise a low pressure compressor 22 located upstream of a high pressure compressor 24 and a high pressure turbine located upstream of a low pressure turbine. For example, the compressor 16 may be a multi-stage compressor 16 that has a low-pressure compressor 22 and a high-pressure compressor 24 and the turbine 20 may be a multistage turbine 20 that has a high-pressure turbine and a low-pressure turbine. In one embodiment, the low-pressure compressor 22 is connected to the low-pressure turbine and the high pressure compressor 24 is connected to the high-pressure turbine.
Referring now to
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While an elevated temperature cure cycle, at above room temperature, for example, 250 degrees F., is not necessary, in some embodiments such a cure may be performed to improve mechanical properties of the adhesive. Although some distortion may occur during the elevated temperature cure cycle, the since the stress-free condition of the fan blade 34 is at room temperature rather than at the elevated temperature, the magnitude of the distortion will be reduced.
While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
