Altering structural response of two-piece hollow-vane assembly by changing the cover composition

A hollow vane assembly including an open body including an interior; at least one cover support structure formed in said open body proximate the interior; a cover brazed to the open body to form at least one flow passage; and at least one ply formed in the cover.

BACKGROUND

The present disclosure is directed to a hollow vane with an open body and a cover with altered composition to modify the structural response of the vane.

Hollow vanes are typically utilized to enable air, either hot or cold, to flow through the part to achieve a desired thermal effect. Historically, hollow vanes have been manufactured by casting the external airfoil shape with cores located internally within the mold. This method results in a hollow cavity within the cast part, however, castings, from both a process capability and supplier willingness perspectives, are not capable of meeting the dimensional and material requirements as demanded by the engine operating environment.

What is needed is a vane cover that can be modified to adapt the vibratory characteristics of the vane for a predetermined operating service.

SUMMARY

In accordance with the present disclosure, there is provided a process of tailoring vibratory characteristics of a cover for an open body hollow vane assembly comprising forming the open body, the open body including an interior; forming at least one cover support structure in said open body proximate the interior; forming a cover, the cover being configured to attach to the open body to form at least one flow passage; forming at least one ply in the cover; and brazing the cover to the open body.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming the at least one ply integral with the surface of the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising disposing a dampener material between an outer layer and an inner layer of the cover to form the at least one ply in the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming an airfoil from the combination of the open body brazed together with the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming a dual walled structure having contoured surfaces including the at least ply formed by additive and/or subtractive processes.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising modifying a vibratory characteristic of the cover with the at least one ply.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising changing a modal shape of the cover to enhance the stiffness of the cover locally responsive to aerodynamic forces created by a working fluid flowing over the hollow vane assembly.

In accordance with the present disclosure, there is provided a hollow vane assembly comprising an open body including an interior; at least one cover support structure formed in said open body proximate the interior; a cover brazed to the open body to form at least one flow passage; and at least one ply formed in the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the at least one ply includes a dampener material between an outer layer and an inner layer of the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the at least one ply includes material attached to the surface of the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include a dual walled structure having contoured surfaces and the at least one ply is formed by the open body together with the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the at least one ply is configured to modify a vibratory characteristic of the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the at least one ply includes layers of material that are distributed across the surface of the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the at least one ply is formed by layering material on the surface of the cover.

In accordance with the present disclosure, there is provided a process for modifying a vibratory characteristic of a cover to an open body comprising forming an open body, the open body includes a leading edge opposite a trailing edge, the open body includes a pressure side and suction side opposite the pressure side, the open body including an interior; forming a cover, the cover being configured to couple with the open body proximate the pressure side to form at least one flow passage; forming at least one ply in the cover; and attaching the cover to the open body.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprises layering a dampener material between an outer layer and an inner layer of the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising modifying a vibratory characteristic of the cover with the at least one ply formed in the cover.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising changing a modal shape of the cover to enhance the stiffness of the cover locally responsive to aerodynamic forces created by a working fluid flowing over the hollow vane assembly.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming a dual walled structure having contoured surfaces including the at least one ply formed by additive and/or subtractive processes.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising forming an airfoil from the combination of the open body together with the cover having the at least one ply, the airfoil being responsive to the at least one ply.

A further embodiment of any of the foregoing embodiments may additionally and/or alternatively include the process further comprising adding layers of mass at a predetermined location on the surface of the cover.

Other details of the hollow vane assembly are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.

DETAILED DESCRIPTION

FIG.1schematically illustrates a gas turbine engine20. The gas turbine engine20is disclosed herein as a two-spool turbofan that generally incorporates a fan section22, a compressor section24, a combustor section26and a turbine section28. The fan section22may include a single-stage fan42having a plurality of fan blades43. The fan blades43may have a fixed stagger angle or may have a variable pitch to direct incoming airflow from an engine inlet. The fan42drives air along a bypass flow path B in a bypass duct13defined within a housing15such as a fan case or nacelle, and also drives air along a core flow path C for compression and communication into the combustor section26then expansion through the turbine section28. A splitter29aft of the fan42divides the air between the bypass flow path B and the core flow path C. The housing15may surround the fan42to establish an outer diameter of the bypass duct13. The splitter29may establish an inner diameter of the bypass duct13. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

The low speed spool30generally includes an inner shaft40that interconnects, a first (or low) pressure compressor44and a first (or low) pressure turbine46. The inner shaft40is connected to the fan42through a speed change mechanism, which in the exemplary gas turbine engine20is illustrated as a geared architecture48to drive the fan42at a lower speed than the low speed spool30. The inner shaft40may interconnect the low pressure compressor44and low pressure turbine46such that the low pressure compressor44and low pressure turbine46are rotatable at a common speed and in a common direction. In other embodiments, the low pressure turbine46drives both the fan42and low pressure compressor44through the geared architecture48such that the fan42and low pressure compressor44are rotatable at a common speed. Although this application discloses geared architecture48, its teaching may benefit direct drive engines having no geared architecture. The high speed spool32includes an outer shaft50that interconnects a second (or high) pressure compressor52and a second (or high) pressure turbine54. A combustor56is arranged in the exemplary gas turbine20between the high pressure compressor52and the high pressure turbine54. A mid-turbine frame57of the engine static structure36may be arranged generally between the high pressure turbine54and the low pressure turbine46. The mid-turbine frame57further supports bearing systems38in the turbine section28. The inner shaft40and the outer shaft50are concentric and rotate via bearing systems38about the engine central longitudinal axis A which is collinear with their longitudinal axes.

The low pressure compressor44, high pressure compressor52, high pressure turbine54and low pressure turbine46each include one or more stages having a row of rotatable airfoils. Each stage may include a row of static vanes adjacent the rotatable airfoils. The rotatable airfoils and vanes are schematically indicated at47and49.

The engine20may be a high-bypass geared aircraft engine. The bypass ratio can be greater than or equal to 10.0 and less than or equal to about 18.0, or more narrowly can be less than or equal to 16.0. The geared architecture48may be an epicyclic gear train, such as a planetary gear system or a star gear system. The epicyclic gear train may include a sun gear, a ring gear, a plurality of intermediate gears meshing with the sun gear and ring gear, and a carrier that supports the intermediate gears. The sun gear may provide an input to the gear train. The ring gear (e.g., star gear system) or carrier (e.g., planetary gear system) may provide an output of the gear train to drive the fan42. A gear reduction ratio may be greater than or equal to 2.3, or more narrowly greater than or equal to 3.0, and in some embodiments the gear reduction ratio is greater than or equal to 3.4. The gear reduction ratio may be less than or equal to 4.0. The fan diameter is significantly larger than that of the low pressure compressor44. The low pressure turbine46can have a pressure ratio that is greater than or equal to 8.0 and in some embodiments is greater than or equal to 10.0. 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. Low pressure turbine46pressure ratio is pressure measured prior to an inlet of low pressure turbine46as related to the pressure at the outlet of the low pressure turbine46prior to an exhaust nozzle. 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. All of these parameters are measured at the cruise condition described below.

A significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section22of the engine20is 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 pounds-mass per hour lbm/hr of fuel flow rate being burned divided by pounds-force lbf of thrust the engine produces at that minimum point. The engine parameters described above, and those in the next paragraph are measured at this condition unless otherwise specified.

“Low fan pressure ratio” is the pressure ratio across the fan blade43alone, without a Fan Exit Guide Vane (“FEGV”) system. A distance is established in a radial direction between the inner and outer diameters of the bypass duct13at an axial position corresponding to a leading edge of the splitter29relative to the engine central longitudinal axis A. The low fan pressure ratio is a spanwise average of the pressure ratios measured across the fan blade43alone over radial positions corresponding to the distance. The low fan pressure ratio can be less than or equal to 1.45, or more narrowly greater than or equal to 1.25, such as between 1.30 and 1.40. “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” can be less than or equal to 1150.0 ft/second (350.5 meters/second), and greater than or equal to 1000.0 ft/second (304.8 meters/second).

Referring also toFIG.2shows an exemplary two piece hollow-vane assembly60. The hollow-vane assembly60includes an open body62that can be a single piece design, being completely integral or monolithic. The two piece hollow-vane assembly60includes a cover64that is attachable to the open body62. The open body62includes cover support structure(s)66. The open body62and cover64are combined to form an airfoil68of a vane70when brazed together. It is contemplated that the hollow-vane assembly60can also be configured as other dual walled structures having contoured surfaces, such as a turbine blade. The hollow-vane assembly60can include a three dimensionally contoured shape. The three dimensional contoured surface can refer to a surface defined by an X, Y, and Z axis. The three dimensional contoured surface can vary from point to point to include surface variation of X, Y and Z coordinates.

The vane assembly60is shown with representative fluid flow passages72with flow arrow74. The flow arrow74shows an exemplary cooling/heating fluid76flow through the fluid flow passages72at the interior78formed by the open body62and cover64. The flow passages72can be configured as multiple cooling channels72that allow for cooling fluid76to flow through the interior78.

The open body62and cover64can be constructed from rigid materials, such as a metal alloy and in alternative embodiments, from heat resistant super alloy composition, nickel-based, or cobalt based compositions. The open body62and cover64can be made of the same material or different materials.

Referring also toFIG.3, vane assembly60is shown. The open body62can be formed from a casting, for example. The open body62can include a leading edge80opposite a trailing edge82, a pressure side86and suction side84opposite the pressure side86(FIG.2). The open body62including the cover support structures66allow for the formation of the flow passages72. The cover support structure66can form an interior wall88. The cover support structure66can be raised surface features of the open body62. The cover support structure66can extend from the open body62distally.

The cover support structure66can form parts of the flow passages72along with the cover64and open body62. The open body62with integral cover support structure(s)66can be manufactured via a manufacturing process that supports the geometric and material capability needs of the vane60. Potential manufacturing options for the open body62can include casting, additive manufacturing, or conventional machining.

Once the open body62is manufactured all surfaces of the vane60, including the now exposed interior78of the open body62, can be post processed to achieve the desired metallurgical properties.

In parallel to the manufacturing of the open body62, the cover64can be fabricated. In addition to the manufacturing options available for the open body62the cover64can be formed to the desired geometry via conventional metal forming methods like stamping, deep drawing, or hydroforming, and machining via multi-axis CNC.

The cover64can be attached to the open body62via a variety of techniques, such as laser welding or brazing with structural brazing joints90. The geometry of the structural brazing joints90is dictated by the location along the vane assembly60. For example, shown inFIG.3, the brazing joint90is located proximate the leading edge80. The leading edge80can include a non-structural seam92that can be filled and polished flush for aero considerations.

Referring also toFIG.4, the cover64can include layers or plies, at least one ply94as shown inFIGS.2,3and4. The plies94can be formed at a variety of locations and sizes and can be integral with the cover64. The plies94can be material added/attached to an outer surface96or inner surface98of the cover64. The plies94can be placed along a variety of locations across the surfaces96,98.

In an exemplary embodiment, the plies94can include a dampener material100that can be employed in the plies94. As seen inFIG.4the dampener material100is located between an outer layer102and inner layer104. In an exemplary embodiment, the dampener100can be an elastomer material between two metal layers102,104. The dampener material100can be coated having a thickness T. The thickness T can range from about 10 mils to about 50 mils (thousandth of an inch). In an exemplary embodiment the thickness T of the coating can be tailored to be a predetermined thickness of 50 mils depending on the specific frequency range that is targeted to be dampened. The predetermined thickness provides a technical advantage because it can provide more damping without compromising the structural integrity of the vane.

The dampener material100can be a viscoelastic material, a super-elastic memory alloy and combinations thereof. The viscoelastic material can exhibit both elastic and viscous behavior when deformed. There are three main characteristics of viscoelastic materials, creep, stress relaxation, and hysteresis. The creep phenomenon is used to describe the continued deformation of a viscoelastic material after the load has reached a constant state. A superelastic alloy can belong to the larger family of shape-memory alloys. When mechanically loaded, a superelastic alloy deforms reversibly to very high strains (up to 10%) by the creation of a stress-induced phase. When the load is removed, the new phase becomes unstable and the material regains its original shape.

In this embodiment, the inner layer104can be brazed to the open body62first, with Braze temperatures at about 1800 Fahrenheit. Then, the dampener material100(not capable of 1800 F) and the outer layer102can be bonded in place. A final perimeter laser weld can secure the outer layer102to the open body62.

The plies94can alter the structural response and redistribute the stress on the cover64. Redistribution of the stress on the cover64can enhance the durability of the vane assembly60and prolong the life of the brazing joint90.

The plies94are configured to modify the vibratory characteristics of the cover64. The plies94are configured to change the modal shapes of the cover64to enhance the stiffness of the cover64locally responsive to aerodynamic forces created by the working fluid flowing over the vane assembly60.

The plies94can provide the means to alter the airfoil68stiffness and tailor to the vibratory characteristics of the airfoil68in different applications. The capacity to tailor the vibratory characteristics can allow the same engine module or components to be modified and re-used in different applications. For example, taking an engine designed for certain cruise speeds and modifying the plies94for use at other cruise speeds or from a steady flight to a more variable flight pattern (cruise versus repeated take-off/land). Engines that spend significant time at cruise are subjected to longer term, consistent vibrations or constant levels of vibration. By comparison, engines experience higher spikes in vibration during take-off and landing. By tailoring the airfoil68to the intended purpose of the engine, one can optimize the airfoil68for these constant vibrations at cruise or frequent spikes during take-off/land. This will allow one to optimize part life based on material fatigue.

Similarly to the open body62, post processing of all part surfaces may be performed on the cover64to achieve the desired metallurgical properties.

With both the open body62and cover64fabrication completed the cover64can be permanently joined to the open body62via brazing. Any subsequent heat treatment, final finishing, inspections, etc. can follow the brazing.

Referring also toFIG.5a process map showing the process200. The process200can include the step202of forming the open body62. The next step204can include forming the cover support structure66in the open body62. The next step206can include forming the cover64. The next step208can include forming the plies94in the cover64. The next step210can include brazing the cover64to the open body62. The cover support structure66can be coupled to the cover64by brazing.

A technical advantage of the disclosed hollow vane assembly includes the selection of a manufacturing method that meets the geometric requirements of the hardware while reducing the metallurgical shortfalls imposed by when casting hollow vanes.

Another technical advantage of the disclosed hollow vane assembly includes direct machining access within the internal passageways of the vane.

Another technical advantage of the disclosed hollow vane assembly includes capacity to optimize the geometry for strength/weight.

Another technical advantage of the disclosed hollow vane assembly includes capacity to alter the exterior structure of the cover.

Another technical advantage of the disclosed hollow vane assembly includes capacity to modify the modal response of the airfoil by use of plies.

Another technical advantage of the disclosed hollow vane assembly includes the capacity to modify the structural behavior of the airfoil at different operating points of the engine.

Another technical advantage of the disclosed hollow vane assembly includes the capacity to optimize the airfoil structure for stresses at different engine operating points.

Another technical advantage of the disclosed hollow vane assembly includes the capacity to alter the stiffness of the airfoil.

Another technical advantage of the disclosed hollow vane assembly includes the optimization of the airfoil by use of the plies for predetermined modal shapes and stresses at different engine operating points.

Another technical advantage of the disclosed hollow vane assembly includes tailoring the airfoils of the engine for different uses.

Another technical advantage of the disclosed hollow vane assembly includes tailoring the airfoils of the engine for different air-frame applications.

There has been provided a hollow vane assembly. While the hollow vane assembly has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.