Rotating airfoil assembly

Abstract

A rotating airfoil includes a body and a damper located within the body. The body has a root end and a tip end. The rotating airfoil has a natural frequency, and the damper has a natural frequency. The natural frequency of the damper is different than the natural frequency of the rotating airfoil.

Description

Technical Field

[0001] This disclosure relates to a rotating airfoil assembly, specifically, a rotating airfoil assembly for an engine that generates thrust for an aircraft, such as a fan or propeller. Background Technology

[0002] The thrust used to move an aircraft in the air can be generated by multiple airfoil elements rotating about a central axis, such as fan blades in a ductless single-fan engine or a propeller on a propeller-driven aircraft. When the fan or propeller rotates, some blades move downwards, while others move upwards. When the aircraft is flying horizontally, air flows into the fan or propeller along its axial direction, and the downward-moving and upward-moving blades produce equal amounts of thrust. However, when the aircraft has an angle of attack, air flows into the fan or propeller with a non-axial component, and the thrust produced by the downward-moving blades differs from that produced by the upward-moving blades. For example, when the aircraft is tilted upwards, such as during takeoff, the downward-moving blades produce greater thrust than the upward-moving blades, resulting in asymmetric loading of the fan blades or propeller. Therefore, in one rotation, the rotating airfoil (fan blade or propeller) experiences differential loads (1P loads), resulting in cyclic loading conditions on the rotating airfoil. Among other things, these cyclic loads subject the rotating airfoil to fatigue stress and strain. Attached Figure Description

[0003] The features and advantages of this disclosure will become apparent from the following description of various exemplary embodiments, as illustrated in the accompanying drawings, wherein similar reference numerals generally denote the same, functionally similar, and / or structurally similar elements.

[0004] Figure 1 This is a schematic perspective view of an aircraft having a ductless single-fan engine with a rotating airfoil according to an embodiment of the present disclosure.

[0005] Figure 2 yes Figure 1 The ductless single-fan engine of the aircraft shown is along Figure 1 A schematic cross-sectional view taken from line 2-2 in the diagram.

[0006] Figure 3 yes Figure 1 A front view of the fan (rotating airfoil assembly) of one of the ductless single-fan engines of the aircraft shown.

[0007] Figure 4A The rotating airfoil according to an embodiment of this disclosure is along Figure 2 A schematic cross-sectional view taken from line 4-4 in the diagram.

[0008] Figure 4B This is a schematic cross-sectional view of a rotating airfoil according to another embodiment of the present disclosure.

[0009] Figure 4C This is a schematic cross-sectional view of a rotating airfoil according to another embodiment of the present disclosure.

[0010] Figure 4D This is a schematic cross-sectional view of a rotating airfoil according to another embodiment of the present disclosure.

[0011] Figure 5 It is a graph of the normalized excitation frequency (frequency ratio) and normalized dynamic amplification factor for fan blades with and without vibration dampers.

[0012] Figure 6 This is a schematic cross-sectional view of a rotating airfoil according to another embodiment of the present disclosure.

[0013] Figure 7 This is a schematic cross-sectional view of a rotating airfoil according to another embodiment of the present disclosure.

[0014] Figure 8 yes Figure 7 A detailed view of the adjustable shock absorber, showing Figure 7 Details 8.

[0015] Figure 9 This is a schematic diagram of an adjustable shock absorber according to another embodiment of the present disclosure. Detailed Implementation

[0016] The features, advantages, and embodiments of this disclosure will be apparent or obvious upon consideration of the following detailed description, accompanying drawings, and claims. Furthermore, it should be understood that the following detailed description is exemplary and intended to provide further explanation without limiting the scope of the claimed disclosure.

[0017] Various embodiments are discussed in detail below. Although specific embodiments are discussed, they are for illustrative purposes only. Those skilled in the art will recognize that other components and configurations can be used without departing from the spirit and scope of this disclosure.

[0018] As used herein, the terms “first” and “second” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0019] The terms "front" and "rear" refer to relative positions within a gas turbine engine or vehicle, and specifically to the normal operating posture of the gas turbine engine or vehicle. For example, in the case of 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.

[0020] 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 from which the fluid flows.

[0021] Unless otherwise stated herein, the terms “connection,” “fixation,” “attachment,” “linkage,” etc., refer to both direct connection, fixation, attachment, or linking, and indirect connection, fixation, attachment, or linking through one or more intermediate components or features.

[0022] Unless the context clearly indicates otherwise, the singular forms “a,” “one,” and “the” include plural references.

[0023] Scope limitations are combined and interchanged herein and throughout the specification and claims. Unless the context or language otherwise indicates, such scopes are identified and include all subscopes contained herein. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0024] As described above, rotating airfoils, such as fan blades of a turbofan engine fan or propellers on a propeller-driven aircraft, may experience differential loads (1P loads) during rotation when the airfoil is at an angle (e.g., tilted upwards or downwards) relative to the airflow entering the fan or propeller about its axis of rotation. This cyclic load is the excitation frequency (1P excitation), which can cause vibrations in the rotating airfoil. In the embodiments discussed herein, the rotating airfoil includes a damper tuned to reduce vibrations caused by this 1P excitation, thereby reducing fatigue and other stresses and strains on the rotating airfoil.

[0025] The rotating airfoil discussed in this article applies to rotating airfoil assemblies used to generate thrust for fixed-wing aircraft, particularly open rotor engines, such as propeller or ductless fan engines. Figure 1 This is a perspective view of an aircraft 10 that can be implemented in various preferred embodiments. The aircraft 10 includes a fuselage 12, a pair of wings 14 attached to the fuselage 12, and a tail 16. The aircraft 10 also includes a propulsion system that generates the thrust required to propel the aircraft 10 during flight, taxiing operations, etc. Figure 1 The propulsion system of the aircraft 10 shown includes a pair of engines 100. In this embodiment, each engine 100 is attached to one of the wings 14 via a pylon 18 in an underwing configuration. Although the engines 100 are in Figure 1The engine 100 is shown attached to wing 14 in an underwing configuration, but in other embodiments, the engine 100 may have an alternative configuration and be coupled to other parts of the aircraft 10. For example, the engine 100 may additionally or alternatively include one or more aspects coupled to other parts of the aircraft 10 (e.g., tail 16 and fuselage 12).

[0026] As will be referenced below Figure 2 As further described, Figure 1 The engine 100 shown is a ductless single-fan engine, each capable of selectively generating propulsive thrust for the aircraft 10. The amount of propulsive thrust can be at least partially based on thrust generated via fuel system 130 (see fuel system 130). Figure 2 The fuel volume supplied to the ductless single-fan engine is controlled. The aviation turbine fuel in the embodiments discussed herein is a combustible hydrocarbon liquid fuel with the desired carbon number, such as kerosene-based fuel. The fuel is stored in fuel tank 131 of fuel system 130. Figure 1 As shown, at least a portion of the fuel tank 131 is located within each wing 14, and a portion of the fuel tank 131 is located within the fuselage 12 between the wings 14. However, the fuel tank 131 may be located in other suitable locations within the fuselage 12 or the wings 14. The fuel tank 131 may also be entirely located within the fuselage 12 or the wings 14. The fuel tank 131 may also be a separate tank rather than a single integral body; for example, two tanks may each be located within their respective wings 14.

[0027] Figure 2 It is used for Figure 1 A schematic cross-sectional view of one of the engines 100 used in the propulsion system of the aircraft 10 shown. Figure 2 The cross-sectional view is along Figure 1 The line 2-2 in the diagram is cut off. As mentioned above, engine 100 is a ductless single-fan engine. The ductless single-fan engine 100 has an axial direction A (parallel to the direction in the diagram). Figure 2 The diagram shows the longitudinal centerline 101 extension (for reference), the radial direction R, and the circumferential direction. The circumferential direction (… Figure 2 (Not depicted) extends in the direction of rotation about the longitudinal centerline 101. The ductless single-fan engine 100 includes a fan section 102 and a turbine 104 disposed downstream of the fan section 102.

[0028] Figure 2The turbine 104 depicted includes a tubular housing 106 (also referred to as a casing or nacelle) defining an inlet 108. In this embodiment, the inlet 108 is annular. The housing 106 surrounds an engine core that includes, in series flow relationships, a compressor section comprising a turbocharger or low-pressure (LP) compressor 110 and a high-pressure (HP) compressor 112; a combustion section 114; a turbine section comprising a high-pressure (HP) turbine 116 and a low-pressure (LP) turbine 118; and an exhaust nozzle section 120. The compressor section, combustion section 114, and turbine section together at least partially define a core airflow path 121 extending from the inlet 108 to the exhaust nozzle section 120. The turbine 104 also includes one or more drive shafts. More specifically, turbine 104 includes a high-pressure (HP) shaft or spool 122 that drives an HP turbine 116 to an HP compressor 112, and a low-pressure (LP) shaft or spool 124 that drives an LP turbine 118 to an LP compressor 110.

[0029] A ductless single-fan engine 100, more specifically, a turbine 104, is capable of operating in conjunction with and receiving a fuel flow from a fuel system 130. The fuel system 130 includes a fuel delivery assembly 133 that provides a fuel flow from a fuel tank 131 to the ductless single-fan engine 100, and more specifically, to a plurality of fuel nozzles 142 that inject fuel into the combustion chamber of a combustor 140 in a combustion section 114. The fuel delivery assembly 133 includes pipes, conduits, ducts, etc., to fluidly connect various components of the fuel system 130 to the ductless single-fan engine 100. The fuel tank 131 is configured to store hydrocarbon fuel, and hydrocarbon fuel is supplied from the fuel tank 131 to the fuel delivery assembly 133. The fuel delivery assembly 133 is configured to deliver hydrocarbon fuel between the fuel tank 131 and the ductless single-fan engine 100, and thus provide a flow path (fluid path) for the hydrocarbon fuel from the fuel tank 131 to the ductless single-fan engine 100.

[0030] Fuel system 130 includes at least one fuel pump fluidly connected to fuel delivery assembly 133 to direct fuel flow through fuel delivery assembly 133 to ductless single-fan engine 100. One such pump is a main fuel pump 135. The main fuel pump 135 is a high-pressure pump and is the primary source of pressure rise in the fuel delivery assembly 133 between fuel tank 131 and ductless single-fan engine 100. The main fuel pump 135 can be configured to increase the pressure in fuel delivery assembly 133 to a pressure greater than the pressure in the combustion chamber of burner 140.

[0031] Fuel system 130 also includes a fuel metering unit 137 in fluid communication with fuel delivery assembly 133. Any fuel metering unit 137 can be used, including, for example, a metering valve. Fuel metering unit 137 is located downstream of main fuel pump 135 and upstream of fuel manifold 139, which is configured to dispense fuel to fuel nozzles 142. Fuel system 130 is configured to supply fuel to fuel metering unit 137, and fuel metering unit 137 is configured to receive fuel from fuel tank 131. Fuel metering unit 137 is further configured to supply a fuel flow to ductless single-fan engine 100 in a desired manner. More specifically, fuel metering unit 137 is configured to meter fuel and supply a desired fuel volume to fuel manifold 139 of ductless single-fan engine 100 at, for example, a desired flow rate. Fuel manifold 139 is fluidly connected to fuel nozzles 142 and dispenses (provides) the received fuel to a plurality of fuel nozzles 142, where the fuel is injected into the combustion chamber of burner 140 and burned. The regulating fuel metering unit 137 changes the volume of fuel supplied to the combustion chamber, and thus changes the amount of propulsive thrust generated by the pipeless single-fan engine 100 to propel the aircraft 10.

[0032] The ductless single-fan engine 100 also includes various auxiliary systems to assist in the operation of the ductless single-fan engine 100 and / or the aircraft 10. For example, the ductless single-fan engine 100 may include a main lubrication system 152, a compressor cooling air (CCA) system 154, an active thermal gap control (ATCC) system 156, and a generator lubrication system 158, each in... Figure 2The diagram is schematically depicted. The main lubrication system 152 is configured to provide lubricant to various bearings and gear meshes, such as in the compressor section, turbine section, HP shaft 122, and LP shaft 124. The lubricant provided by the main lubrication system 152 can increase the service life of these components and can remove a certain amount of heat from these components by using one or more heat exchangers. The compressor cooling air (CCA) system 154 supplies air from one or both of the HP compressor 112 or LP compressor 110 to one or both of the HP turbine 116 or LP turbine 118. The active thermal gap control (ATCC) system 156 is used to minimize the gap between the turbine blade tips and the casing wall as the casing temperature changes during flight missions. The generator lubrication system 158 provides lubrication to the electric generator (not shown) and provides cooling / de-heating to the electric generator. The electric generator can provide power to, for example, a starter motor for the ductless single-fan engine 100 and / or various other electronic components of the ductless single-fan engine 100 and / or the aircraft 10. The lubrication system for the pipeless single-fan engine 100 (e.g., the main lubrication system 152 and the generator lubrication system 158) can use hydrocarbon fluids (e.g., oil) for lubrication, wherein the oil circulates through the inner surface of the return line.

[0033] The fan section 102 of the ductless single-fan engine 100 includes a plurality of fan blades 162, also referred to herein as rotating airfoils, coupled to a fan hub 164 (or disc). The fan blades 162 and the fan hub 164 are circumferentially rotatable together about an axis of rotation 161, which in this embodiment coincides with a longitudinal centerline (axis) 101. In this embodiment, a rotator 160 is connected to the fan hub 164 and rotates relative to the housing 106. Each fan blade 162 is an airfoil, and more specifically, a rotating airfoil. In this embodiment, the fan blades 162 together with the fan hub 164 constitute a rotating airfoil assembly.

[0034] The turbine 104 in this embodiment is a torque-generating system that produces torque to rotate fan blades 162. The turbine 104 is configured to operate (e.g., rotate) a fan hub 164. The fan hub 164 may be coupled to a shaft, and more specifically, to an LP shaft 124 of the turbine 104, and the LP shaft 124 rotates the fan blades 162 and the fan hub 164. In some embodiments, in a direct-drive configuration, the LP shaft 124 may be coupled to the fan hub 164; however, in this embodiment, the LP shaft 124 is coupled to a gearbox 126, which in turn transmits rotational (torsional) force to rotate the fan hub 164.

[0035] One or more outlet guide vanes 166 may be coupled to the housing 106. In this embodiment, the outlet guide vanes 166 are positioned behind the fan blades 162. In this embodiment, the housing 106 is stationary such that the one or more outlet guide vanes 166 do not rotate about the longitudinal centerline 101, and are therefore stationary relative to rotation about the longitudinal centerline 101. Although the outlet guide vanes 166 are stationary relative to the longitudinal centerline 101, the outlet guide vanes 166 are capable of rotating or moving relative to the housing 106 to guide airflow in a particular direction.

[0036] During the operation of the ductless single-fan engine 100, air is drawn from... Figure 2 left side Figure 2 The airflow flows to the right. A portion of the airflow can pass over the fan blades 162 and the outlet guide vanes 166. A portion of the airflow can enter the housing 106 through the annular inlet 108, because the air flowing through the core airflow path 121 will mix with fuel for combustion in the combustor 140 and be discharged through the injection exhaust nozzle section 120. As described above, the outlet guide vanes 166 can be movable relative to the housing 106 to guide the airflow in a specific direction. Each outlet guide vane 166 can be movable to adjust the tilt, pitch, sweep, or any combination thereof of the outlet guide vane 166.

[0037] exist Figure 1 and 2 In the illustrated embodiment, the front end or front portion of the housing 106 includes one or more fan blades 162 and one or more outlet guide vanes 166. In other embodiments, the one or more fan blades 162 and one or more outlet guide vanes 166 may have different arrangements relative to the housing 106. For example, the one or more fan blades 162 and one or more outlet guide vanes 166 may be located at the rear end or rear portion of the housing 106, for example, coupled to the rear portion of the housing 106. More specifically, the one or more fan blades 162 and one or more outlet guide vanes 166 may be coupled to the rear portion of the housing 106.

[0038] In other embodiments, the engine according to this disclosure may be configured to have stationary blades positioned in front of the rotating fan blades 162 (therefore, blade 166 is an inlet guide blade). Although the outlet guide blades 166 may be stationary and not rotate about the longitudinal centerline 101, as described above, one or more outlet guide blades 166 may rotate in the opposite direction to one or more fan blades 162, such that the one or more outlet guide blades 166 are counter-rotating rotors in a counter-rotating open rotor (CROR) engine. A propeller configuration in which the rotor is in front of the pylon 18 or a tractor configuration in which the rotor is behind the pylon 18 is contemplated. In this case, the counter-rotating rotor may also be a rotating airfoil as part of a rotating airfoil assembly, as discussed further below.

[0039] Figure 1 and Figure 2 The example of the rotating airfoil assembly shown is fan blade 162 together with fan hub 164, but the embodiments discussed herein are applicable to other rotating airfoil assemblies. Other rotating airfoil assemblies include, for example, propeller assemblies, such as propeller assemblies for turboprop engines. Such propeller assemblies may include multiple propeller blades coupled to and extending outward from a propeller shaft. The propeller assembly of a turboprop engine may be driven by a turbine (similar to turbine 104 discussed above) to rotate about the axis of rotation of the propeller shaft. The propeller blades are airfoils, more specifically, rotating airfoils, and the propeller assembly is another example of a rotating airfoil assembly. The propeller assembly is an open rotor system, which may also experience asymmetrical loads on the propeller blades if the longitudinal centerline of the turboprop engine is at an angle (e.g., tilted upwards or downwards) relative to the airflow entering the propeller assembly.

[0040] The above discussion is used for Figures 1 to 2 The torque generation system of the engine 100 shown is a turbine 104. However, other suitable torque generation systems can be used for rotating airfoils (e.g., fan blades 162) and airfoil assemblies (e.g., fan hub 164 and fan blades 162). Other suitable torque generation systems include other engines, such as reciprocating engines. Although Figure 1 The aircraft 10 shown is an airplane, but the embodiments described herein are also applicable to other aircraft 10, including, for example, other fixed-wing unmanned vehicles (UAVs). Furthermore, although not described herein, in other embodiments, the embodiments discussed herein are applicable to any rotating airfoil and rotating airfoil assembly, such as wind turbine blades.

[0041] Figure 3 A rotary airfoil assembly 200 comprising a plurality of rotary airfoil elements 202 is shown according to an embodiment. Figure 3The rotating airfoil assembly 200 depicted includes Figure 1 and Figure 2 The rotator 160 of the ductless single-fan motor 100, and Figure 3 This is a front view of the rotator 160. The rotator airfoil 202 (fan blade 162) of the rotator airfoil assembly 200 is... Figure 3 The rotating airfoil 202 rotates clockwise around the rotation axis 201 (rotation axis 161). For the convenience of the following discussion, the angular positions of the rotating airfoil 202 and the rotating airfoil assembly 200 are given relative to the rotation axis 201, as shown below. Figure 3 As shown. Therefore, the rotating airfoil 202 rotates from zero degrees to 180 degrees in the downward direction and from 180 degrees to 360 degrees (zero degrees) in the upward direction.

[0042] Figure 3 The rotation axis 201 is shown to be at an angle (e.g., tilted upwards or downwards) relative to the airflow entering the rotating airfoil 202. More specifically, in Figure 3 In the process, the rotation axis 201 is at a certain angle relative to the airflow entering the rotating airfoil 202, for example, when the aircraft 10 (and Figure 1 When the longitudinal centerline 101 of the ductless single-fan engine 100 tilts upward during takeoff or climb, the rotating airfoil assembly 200 experiences a non-axial component of the airflow in the upward direction (as indicated by the upward arrow). If the rotating airfoil assembly 200 is not tilted, each rotating airfoil 202 produces similar lift at both the top (zero degrees) and bottom (180 degrees) of rotation. However, each rotating airfoil 202 produces less lift as it moves downward from the top (zero degrees) to the bottom (180 degrees) and more lift as it moves upward from the bottom (180 degrees) to the top (zero degrees). This variation in lift occurs... Figure 3 The diagram is illustrated using dashed lines. As the rotating airfoil 202 rotates one revolution, the minimum lift generated by the rotating airfoil 202 is at 90 degrees, increases steadily from that point to 270 degrees, and then decreases steadily as the rotating airfoil 202 continues to rotate. This can be referred to as the load per revolution or 1P load.

[0043] Figure 4A An embodiment of the airfoil assembly 200 described herein is shown. Figure 3 Rotating airfoil 202, such as fan blade 162 of a ductless single-fan engine 100. Figure 4A It is along Figure 2A schematic cross-sectional view taken by line 4-4 in the figure. The rotating airfoil assembly 200 of this embodiment includes a root 212 that engages with a fan hub 164 and connects the rotating airfoil 202 to the fan hub 164. A sparsity 214 is connected to the root 212. The sparsity 214 provides structural support for the rotating airfoil assembly 200. A skin (not shown) forms the outer surface of the rotating airfoil assembly 200. The volume in the rotating airfoil assembly 200 between the sparsity 214 and the skin can be filled with, for example, foam 216. Foam 216 is a lightweight, non-structural component of the rotating airfoil assembly 200 used to fill the gap between the sparsity 214 and the skin. In this embodiment, the sparsity 214 and foam 216 together form the body of the rotating airfoil 202. The rotating airfoil 202 includes a leading edge 222, a trailing edge 224, a root end 226, and a tip 228. Rotating airfoil 202 along the radial direction R of rotating airfoil assembly 200 (see also...) Figure 2 It extends outward from the root end 226 to the tip 228. The longitudinal direction of the rotating airfoil 202 is the radial direction R of the rotating airfoil assembly 200. The rotating airfoil 202 may have any suitable shape, including, for example, an arcuate shape with a suction surface having a convex curvature and a generally flat pressure surface.

[0044] The rotating airfoil 202 of this embodiment includes a cavity 230 and a damper 240 located within the cavity 230. The cavity 230 includes a plurality of walls defining the cavity 230. In this embodiment, the cavity 230 includes a front wall 232, a rear wall 234, a root wall 236, a tip wall 238, a suction sidewall (not shown), and a pressure sidewall (not shown), collectively referred to herein as the sidewalls of the cavity 230. The cavity 230 of this embodiment extends in the radial direction R of the rotating airfoil 202.

[0045] exist Figure 4A In the illustrated embodiment, cavity 230 and damper 240 are located within spar 214. In some embodiments, such as in Figure 4A In the embodiment shown, the cavity 230 and the damper 240 are located closer to the tip 228 than the root 226, and can be formed on the outer half of the rotating airfoil 202 in the radial direction R.

[0046] The damper 240 of this embodiment is a cantilever beam located within the cavity 230 and, similar to the cavity 230, extends in the radial direction R of the rotating airfoil 202. Although shown and described herein as a cantilever beam, the damper 240 can have any suitable shape. The damper 240 includes an attachment end 242 and a free end 244. The attachment end 242 is opposite the free end 244 in the radial direction R of the rotating airfoil 202. The attachment end 242 is attached to one of the sidewalls of the cavity 230, such as the tip wall 238. The free end 244 is not attached to the sidewall of the cavity 230 or another part of the rotating airfoil 202. The damper 240 is sized to have a width W and a depth (inside and outside the page) to create space (gap) between the damper 240 and the sidewalls of the cavity 230 (excluding the sidewall of the cavity 230 to which the damper 240 is attached at the attachment end 242) (e.g., front wall 232, rear wall 234, root wall 236, suction sidewall (not shown), and pressure sidewall (not shown)). Furthermore, the damper 240 has a length L such that space (gap) exists between the free end 244 and one of the walls of the cavity 230 (e.g., root wall 236). When the damper 240 is cantilevered and sized in this way, at the excitation frequency (ω... exc When a vibration is applied to the rotating airfoil 202, the free end 244 vibrates freely within the cavity 230. In some embodiments, the free end 244 is configured to vibrate freely within the cavity 230 when the rotating airfoil 202 is subjected to an excitation frequency (ω) different from the natural frequency of the rotating airfoil 202. exc It vibrates within the cavity 230 without contacting the wall of the cavity 230.

[0047] Figure 4B This is a schematic cross-sectional view of the rotating airfoil 302 according to another aspect of this disclosure, the rotating airfoil 302 being... Figure 4A A variant of the rotating airfoil 202. The rotating airfoil 302 is substantially similar to the rotating airfoil 202; therefore, similar parts will be identified with similar numbers. It should be understood that, unless otherwise stated, the description of similar parts of the rotating airfoil 202 applies to the rotating airfoil 302.

[0048] In some embodiments, such as in Figure 4B In the illustrated embodiment, cavity 230 can be machined from tip 228 into spar 214, and damper 240 is inserted from tip 228 into cavity 230. In this embodiment, spar 214 extends to tip 228 and cavity 230 is a hole formed in spar 214 extending inward from tip 228. In this embodiment, attachment end 242 is connected to tip 228 of rotating airfoil 302.

[0049] Figure 4CThis is a schematic cross-sectional view of a rotating airfoil 402 according to another aspect of this disclosure, wherein the rotating airfoil 402 is Figure 4A A variant of the rotating airfoil 202. The rotating airfoil 402 is substantially similar to the rotating airfoil 202; therefore, similar parts will be identified with similar numbers. It should be understood that, unless otherwise stated, the description of similar parts of the rotating airfoil 202 applies to the rotating airfoil 402.

[0050] exist Figure 4C In the embodiment shown, the cavity 230 can be machined into the spar 214 via the root 212.

[0051] Figure 4D This is a schematic cross-sectional view of a rotating airfoil 502 according to another aspect of this disclosure, wherein the rotating airfoil 502 is Figure 4A A variant of the rotating airfoil 202. The rotating airfoil 502 is substantially similar to the rotating airfoil 202; therefore, similar parts will be identified with similar numbers. It should be understood that, unless otherwise stated, the description of similar parts of the rotating airfoil 202 applies to the rotating airfoil 502.

[0052] In some embodiments, such as in Figure 4D In the illustrated embodiment, the damper can be positioned at an alternative location within the rotating airfoil 502. Although the cavity 230 and the damper 240 may preferably be located within the spar 214 (e.g., Figure 4A , 4B (as shown in 4C), but the cavity 230 and the damper 240 can be located in other suitable positions within the rotating airfoil 502, including in the foam 216, such as... Figure 4D As shown.

[0053] Figure 5 It is a graph of the normalized excitation frequency (x-axis) versus the normalized dynamic amplification factor (y-axis) of the rotating airfoil, such as... Figure 4A The rotating airfoil 202 is similarly applicable to Figure 4B-4D Rotating airfoil components 302, 402, and 502. The normalized excitation frequency is, for example, the excitation frequency (ω). exc Divide by the natural frequency (ω) of the rotating airfoil 202 n The frequency ratio of the rotating airfoil 202 without damper 240 to the input (excitation) frequency. Figure 5 The dynamic response of the rotating airfoil 202 with damper 240 to the input (excitation) frequency is shown by solid line 282. Figure 5The dashed line 284 is shown in the figure. The damper 240 also has a natural frequency. In this embodiment, the natural frequency of the damper 240 is tuned to reduce the dynamic response corresponding to the 1P excitation. The natural frequency of the damper 240 is tuned to the 1P excitation frequency, such that the damper 240 reduces the vibration of the main structure (in this case, the rotating airfoil 202) at the 1P excitation frequency.

[0054] exist Figure 5 In the illustrated embodiment, the damper 240 reduces the dynamic amplification of the 1P load to almost negligible amplification. The damper 240 is tuned to have a natural frequency that deviates from (e.g., greater than or less than) the resonant (natural frequency) of the rotating airfoil 202. Preferably, the damper 240 is tuned to have a natural frequency that deviates from the resonant (natural frequency) of the rotating airfoil 202 by at least 10 percent, wherein the natural frequency of the damper 240 is 90 percent or less of the natural frequency of the rotating airfoil 202, or the natural frequency of the damper 240 is 110 percent or more of the natural frequency of the rotating airfoil 202. In some embodiments, the natural frequency of the damper 240 is less than the natural frequency of the rotating airfoil 202 and has a normalized excitation frequency of less than one. The damper 240 preferably has a natural frequency ranging from 25 percent to 90 percent of the natural frequency of the rotating airfoil 202. As described above, the natural frequency of the damper 240 can be greater than the natural frequency of the rotating airfoil 202, and in such an embodiment, the damper 240 preferably has a natural frequency ranging from 110 percent to 150 percent of the natural frequency of the rotating airfoil 202.

[0055] 1P excitation can be used as aircraft 10 ( Figure 1 The speed of the aircraft 10 varies as a function of the angle of attack of the aircraft 10. In the embodiments discussed herein, the 1P excitation is determined for design conditions, wherein the 1P load varies between the aircraft 10 and the engine 100. Figure 1 The highest speed is within the flight envelope of the engine 10. Such design conditions could be, for example, the maximum speed of the aircraft 10 and the angle of attack of the aircraft 10 during takeoff and climb. In some embodiments, the 1P excitation could be the rotational speed of the rotor airfoil assembly 200, and the natural frequency of the damper 240 could be 90% to 110% of the rotational speed of the rotor airfoil assembly 200. The speed of the rotor airfoil assembly 200 can be obtained under the design conditions discussed above, and the speed of the rotor airfoil assembly 200 can be a percentage of the redline speed of the engine 100.

[0056] The use of damper 240 in the manner discussed herein reduces the 1P load and allows for improved design of the rotating airfoil. For example, currently, both the root 212 and the spars 214 are metal components. Damper 240 allows for the use of lower-weight materials, such as composite materials, for one or both of the root 212 and the spars 214. Furthermore, the size of these components can be reduced. Damper 240 alters the dynamic characteristics of the rotating airfoil 202. Damper 240, in particular... Figures 4A to 4C The illustrated embodiment is a passive device that can be implemented without regular maintenance. Since the damper 240 is located inside the rotating airfoil 202 (within the main body), the damper 240 does not affect the aerodynamic performance of the rotating airfoil 202.

[0057] Figure 6 This is a schematic cross-sectional view of a rotating airfoil 602 according to another aspect of this disclosure, wherein the rotating airfoil 602 is Figure 4A A variant of the rotating airfoil 202. The rotating airfoil 602 is substantially similar to the rotating airfoil 202; therefore, similar parts will be identified with similar numbers. It should be understood that, unless otherwise stated, the description of similar parts of the rotating airfoil 202 applies to the rotating airfoil 602.

[0058] A single shock absorber 240 is used in Figures 4A to 4C In the illustrated embodiment. As shown Figure 6 As shown, other embodiments may use multiple dampers 240, for example in Figure 6 In the rotating airfoil 602 shown, each damper 240 can be tuned to accommodate different excitation frequencies. For example, one damper 240 can be tuned to accommodate 1P excitation, and another damper 240 can be tuned to have a natural frequency consistent with some other synchronous or asynchronous stimulus. In some embodiments, the first damper 240 has a first natural frequency and the second damper 240 has a second natural frequency different from the first natural frequency. In this case, the length L of the first damper 240 can be different from the length L of the second damper 240.

[0059] Figure 7 This is a schematic cross-sectional view of a rotating airfoil 702 according to another aspect of this disclosure, wherein the rotating airfoil 702 is Figure 4A A variant of the rotating airfoil 202. The rotating airfoil 702 is substantially similar to the rotating airfoil 202; therefore, similar parts will be identified with similar numbers. It should be understood that, unless otherwise stated, the description of similar parts of the rotating airfoil 202 applies to the rotating airfoil 602.

[0060] Figures 4A to 4CThe damper 240 shown is passive and requires no further tuning or adjustment once manufactured. In some embodiments, the damper 240 may be adjustable to have different natural frequencies. Figure 7 The damper 240 shown is similar to Figure 4B The damper 240 is shown, but the free end 244 includes an adjustable mass 246 that can be moved away from or closer to the attachment end 242 of the damper 240 to change the natural frequency of the damper 240.

[0061] Figure 8 It is a display Figure 7 Detailed view of details 8 of the damper 240. In this embodiment, the damper 240 is actively adjustable, such that, for example, a user or controller 260 moves the adjustable mass block 246. Any suitable method can be used to adjust (move) the adjustable mass block 246, including, for example, an actuator 250, such as a linear actuator, as... Figure 8 As shown. In this embodiment, actuator 250 includes a stepper motor 252 that drives screw 254. Stepper motor 252 rotates screw 254, and as screw 254 rotates, adjustable mass 246 moves closer to or further away from attachment end 242 of damper 240. Actuator 250, and more specifically in this embodiment, stepper motor 252 can be operated by controller 260. Stepper motor 252 is communicatively and operatively coupled to controller 260.

[0062] Controller 260 may be a separate controller portion of the engine controller, which is configured to operate engine 100. Figure 1 Various systems. In this embodiment, the controller 260 is a computing device having one or more processors 262 and one or more memories 264. The processor 262 can be any suitable processing device, including but not limited to microprocessors, microcontrollers, integrated circuits, logic devices, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and / or field-programmable gate arrays (FPGAs). The memory 264 can include one or more computer-readable media, including but not limited to non-transitory computer-readable media, computer-readable non-volatile media (e.g., flash memory), RAM, ROM, hard disk drives, flash drives, and / or other memory devices.

[0063] Memory 264 may store information accessible to processor 262, including computer-readable instructions executable by processor 262. Instructions may be any set or sequence of instructions that, when executed by processor 262, cause processor 262 and controller 260 to perform operations, such as those discussed further below. In some embodiments, instructions may be executed by processor 262 to cause processor 262 to perform any operations and functions configured for it by controller 260, as further described below. Instructions may be software written in any suitable programming language or may be implemented in hardware. Additionally and / or alternatively, instructions may be executed on processor 262 in logically and / or virtually separate threads. Memory 264 may further store data accessible by processor 262.

[0064] The techniques discussed herein refer to computer-based systems and the actions taken by and from computer-based systems, as well as the information sent to and from computer-based systems. Those skilled in the art will recognize that the inherent flexibility of computer-based systems allows for a wide variety of possible configurations, combinations, and divisions of tasks and functions between and within components. For example, the processes discussed herein can be implemented using a single computing device or multiple computing devices working in combination. Databases, memory, instructions, and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel.

[0065] Controller 260 may be communicatively coupled to sensor 266 that measures the excitation frequency (or another input from which controller 260 may determine the excitation frequency). Controller 260 may be configured to receive an input from sensor 266 indicating the measured excitation frequency, and controller 260 may be configured to move adjustable mass 246 based on the measured excitation frequency. Controller 260 may be configured to move adjustable mass 246 to tune damper 240 to the measured excitation frequency. Additionally or alternatively, controller 260 may be configured to receive an input indicating the operating conditions of rotating airfoil assembly 200. The operating conditions of rotating airfoil assembly 200 may be the operating conditions of engine 100 and / or aircraft 10, such as the angle of attack of aircraft 10, airspeed of aircraft 10, or rotational speed of rotating airfoil assembly 200. Controller 260 may be configured to move adjustable mass 246 and tune damper 240 based on the operating conditions of rotating airfoil assembly 200.

[0066] Figure 9This is a detailed view showing an alternative configuration of the damper 240, and more specifically, an alternative configuration of the adjustable mass 246. In this embodiment, the adjustable mass 246 is passively tunable (adjustable). The adjustable mass 246 in this embodiment is slidably connected to a rod 272. The adjustable mass 246 is connected to the attachment end 242 of the damper 240 via a spring 274. The position of the adjustable mass 246 on the rod 272, and thus the natural frequency of the damper 240, is controlled by the centrifugal load on the mass and the spring constant. The position of the adjustable mass 246 on the rod 272 and the distance between the adjustable mass 246 and the attachment end 242 can therefore be based on the rotational speed of the airfoil assembly 200, and more specifically, the rotational speed of the airfoil (e.g., airfoils 202, 302, 402, 502, 602, 702).

[0067] The rotating airfoil components 202, 302, 402, 502, 602, and 702 discussed herein utilize a vibration damper 240, which is tuned to account for excitations deviating from the resonant (natural frequency). In the embodiments discussed above, the vibration damper 240 is tuned to account for 1P excitation. The vibration damper 240 may be tuned to account for other excitations deviating from the resonant (natural frequency) of the rotating airfoil, and in these embodiments, the natural frequency of the vibration damper 240 differs from the natural frequency of the rotating airfoil. The vibration damper 240 reduces vibrations caused by excitations deviating from the resonant (natural frequency), and more specifically, in some embodiments, vibrations caused by 1P excitation, thereby reducing fatigue and other stresses and strains on the rotating airfoil components 202, 302, 402, 502, 602, and 702 and the rotating airfoil assembly 200.

[0068] Further aspects of this disclosure are provided by the subject matter of the following clauses.

[0069] A rotating airfoil includes a body and a damper. The body has a root and a tip. The damper is located within the body. The rotating airfoil has a natural frequency. The damper also has a natural frequency. The natural frequency of the damper is different from the natural frequency of the rotating airfoil.

[0070] According to the aforementioned clause, the natural frequency of the damper differs from the natural frequency of the rotating airfoil by at least 10 percent.

[0071] The rotating airfoil according to any one of the preceding clauses, wherein the natural frequency of the damper is 25 percent to 90 percent of the natural frequency of the rotating airfoil.

[0072] The rotating airfoil according to any one of the preceding clauses, wherein the damper is actively adjustable. The damper is operatively coupled to a controller. The controller is programmed to adjust the natural frequency of the damper based on an input.

[0073] The rotating airfoil according to any one of the preceding clauses, wherein the damper is passively adjustable. The damper includes an adjustable mass block that can be moved to change the natural frequency of the damper. The position of the adjustable mass block is based on the rotational speed of the rotating airfoil.

[0074] The rotating airfoil according to any one of the preceding clauses further includes a plurality of dampers. The plurality of dampers includes a first damper having a first natural frequency and a second damper having a second natural frequency, the second natural frequency being different from the first natural frequency. The first natural frequency and the second natural frequency are different from the natural frequency of the rotating airfoil.

[0075] The rotating airfoil according to any one of the preceding clauses, wherein the main body comprises foam. The damper is located within the foam.

[0076] The rotating airfoil according to any one of the foregoing clauses further includes a spar. The spar is part of the main body, and the damper is located within the spar.

[0077] The rotating airfoil according to any one of the preceding clauses further includes a cavity formed in the spar. The damper is located within the cavity.

[0078] The rotating airfoil according to any one of the preceding clauses, wherein the rotating airfoil has a longitudinal direction. A sparsity extends to a tip. A cavity is a hole extending inward from the tip in the longitudinal direction of the rotating airfoil.

[0079] The rotating airfoil according to any one of the preceding clauses further includes a cavity formed in the body. The cavity includes a plurality of walls defining the cavity, and a vibration damper is located within the cavity. The vibration damper is a cantilever beam having an attached end and a free end. The attached end is attached to at least one of the plurality of walls defining the cavity. The vibration damper is sized and positioned within the cavity such that the free end can vibrate within the cavity when subjected to an excitation frequency.

[0080] The rotating airfoil according to any one of the preceding clauses, wherein the rotating airfoil has a longitudinal direction. Each of the cavity and the damper extends in the longitudinal direction.

[0081] The rotating airfoil according to any one of the preceding clauses, wherein the free end includes an adjustable mass block that is movable relative to the attached end to change the natural frequency of the damper.

[0082] The rotating airfoil according to any one of the preceding clauses, wherein the damper is sized and positioned within the cavity such that a gap is formed between the damper and the sidewall of the cavity.

[0083] According to any one of the preceding clauses, the size of the gap is designed such that when the airfoil is subjected to an excitation frequency less than the natural frequency of the airfoil, the free end of the damper can vibrate within the cavity without contacting the sidewall of the cavity.

[0084] A rotating airfoil assembly includes a rotation axis and a plurality of rotating airfoils according to any one of the preceding claims. The plurality of rotating airfoils are rotatable about the rotation axis.

[0085] According to the aforementioned clause, in the rotating airfoil assembly, when the axis of rotation is at an angle relative to the airflow direction into the plurality of rotating airfoils, the rotating airfoil assembly generates an excitation frequency due to the asymmetrical load on the rotating airfoils. The natural frequency of the damper is the excitation frequency.

[0086] The rotating airfoil assembly according to any one of the preceding clauses, wherein a plurality of rotating airfoils are capable of rotating about a rotation axis at a certain rotational speed. The natural frequency of the damper is 90% to 110% of the rotational speed.

[0087] An engine includes a rotating airfoil assembly according to any one of the preceding clauses. A torque generating system is coupled to the rotating airfoil assembly to rotate the rotating airfoil assembly about its axis of rotation.

[0088] The engine according to any one of the preceding clauses is a ductless single-fan engine. The torque generation system is a turbine of a gas turbine engine. The rotating airfoil assembly is a fan, wherein each of the plurality of rotating airfoils is a fan blade.

[0089] While the foregoing description is directed toward preferred embodiments, other variations and modifications will be apparent to those skilled in the art and can be made without departing from the spirit or scope of this disclosure. Furthermore, features described in connection with one embodiment may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A rotating airfoil, characterized by, include: The main body has a root end and a tip; A cavity formed in the body, the cavity including a plurality of walls defining the cavity; and A vibration damper, located within and arranged within the cavity, moves within the cavity without contacting the cavity walls when the rotating airfoil is subjected to an excitation frequency. The rotating airfoil has a natural frequency, and the damper has a natural frequency, wherein the natural frequency of the damper differs from the natural frequency of the rotating airfoil by at least 10 percent.

2. The rotating airfoil of claim 1, wherein, The natural frequency of the damper is between 25 percent and 90 percent of the natural frequency of the rotating airfoil.

3. The rotating airfoil of claim 1, wherein, The damper is actively adjustable, operatively coupled to a controller, and the controller is programmed to adjust the natural frequency of the damper based on an input.

4. The rotating airfoil of claim 1, wherein, The damper is passively adjustable and includes an adjustable mass block that can be moved to change the natural frequency of the damper. The position of the adjustable mass block is based on the rotational speed of the rotating airfoil.

5. The rotating airfoil of claim 1, wherein, It further includes a plurality of vibration dampers, the plurality of vibration dampers including a first vibration damper having a first natural frequency and a second vibration damper having a second natural frequency, the second natural frequency being different from the first natural frequency, wherein the first natural frequency and the second natural frequency are different from the natural frequency of the rotating airfoil.

6. The rotating airfoil of claim 1, wherein, The main body comprises foam, and the shock absorber is located within the foam.

7. The rotating airfoil of claim 1, wherein, It further includes a spar, which is part of the body and the shock absorber is located within the spar.

8. The rotating airfoil of claim 7, wherein, The cavity is located in the wing spars.

9. The rotating airfoil of claim 8, wherein, The rotating airfoil has a longitudinal direction, the spar extends to the tip, and the cavity is a hole extending inward from the tip in the longitudinal direction of the rotating airfoil.

10. The rotating airfoil according to claim 1, characterized in that, The damper is a cantilever beam having an attached end and a free end, the attached end being attached to at least one of the plurality of walls defining the cavity, and the damper being sized and positioned within the cavity such that the free end is able to vibrate within the cavity when subjected to the excitation frequency.

11. The rotating airfoil of claim 10, wherein, The rotating airfoil has a longitudinal direction, and each of the cavity and the damper extends in the longitudinal direction.

12. The rotating airfoil of claim 10, wherein, The free end includes an adjustable mass block that can move relative to the attached end to change the natural frequency of the damper.

13. The rotating airfoil of claim 10, wherein, The damper is sized and positioned within the cavity such that a gap is formed between the damper and the sidewall of the cavity.

14. The rotating airfoil of claim 13, wherein, The gap is sized such that when the rotating airfoil is subjected to an excitation frequency less than the natural frequency of the rotating airfoil, the free end of the damper can vibrate within the cavity without contacting the sidewall of the cavity.

15. A rotating airfoil assembly, characterized by, include: axis of rotation; and A plurality of the rotating airfoils of claim 1, the plurality of rotating airfoils being rotatable about the axis of rotation.

16. The rotating airfoil assembly of Claim 15, wherein, wherein the rotating airfoil assembly generates the excitation frequency due to asymmetric loading of the rotating airfoils when the axis of rotation is at an angle relative to a direction of airflow of air flowing into the plurality of rotating airfoils, the natural frequency of the damper being the excitation frequency.

17. The rotating airfoil assembly of Claim 15, wherein, wherein the plurality of rotating airfoils are rotatable about the axis of rotation at a rotational speed, the natural frequency of the damper being ninety percent to one hundred and ten percent of the rotational speed.

18. An engine characterized by, comprising: the rotating airfoil assembly of claim 16; and a torque generating system coupled to the rotating airfoil assembly to rotate the rotating airfoil assembly about the axis of rotation of the rotating airfoil assembly.

19. The engine of claim 18, wherein wherein the engine is a ductless single fan engine, the torque generating system is a turbine of a gas turbine engine, and the rotating airfoil assembly is a fan, wherein each of the plurality of rotating airfoils is a fan blade.

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