ORDER TO REDUCE VIBRATION

Description

[0001] The present invention relates to an arrangement for reducing vibration.

[0002] In many – sometimes very different – ​​technical fields, there are structures capable of vibration, whose vibrations, especially the amplitudes of the modes or natural frequencies of the structures, can be reduced by known vibration reduction measures, such as friction damping, the application of additional weights, amplitude limiters, or the use of rheological fluids, active damping systems (e.g., piezoelectric dampers), or coupling with additional spring-mass systems, and / or where vibration reduction can be advantageous, for example, to extend the service life of the structure, reduce noise emissions from the structure, and / or reduce the risk of functional impairment of the structure.

[0003] Examples of such vibrating structures are parts, sections and components of engines, e.g. electric and / or combustion engines, in particular of car engines or ship engines, of turbines, of manufacturing machines, e.g. for milling and / or turning, of engines, in particular aircraft engines, of propulsion systems, for example rocket engines, of structures, e.g. buildings or bridges, of vehicles, in particular automobiles, of aircraft, of rockets, of satellites, of any means of transport or also parts, sections and / or components in contact with them.

[0004] Arrangements with bodies or particles in cavities are known from documents EP3667020A1, US6827551B1, US20120024646A1.

[0005] One objective of an embodiment of the present invention is to provide an improved method of vibration reduction.

[0006] This problem is solved by an arrangement having the features of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

[0007] According to one aspect of the present invention, an arrangement for reducing vibration of an oscillating structure comprises: a structure with at least one mode in at least one direction, and at least one vibration damping device, which has at least one cavity, in particular a closed cavity, formed by the structure or provided on the structure, and has at least one body which is arranged in the at least one cavity to perform impact contacts with the housing such that, as long as the structure is excited in the at least one mode in the at least one direction (by external, self and / or parameter excitation and / or initial conditions), it performs impact contacts with the housing at least intermittently, in particular continuously, wherein a) for a movement B of the at least one body in the at least one direction in the at least one cavity: 0 , 1 × A 0 j < B < 0 , 95 × A 0 j , and / or b) for a mass mi of at least one body, the following applies: m i < μ × M jj , mit μ = a A 1 j A 0 j 2 , und 0 , 000001 < a < 0 , 0009 , where A 0j indicates a vibration amplitude in the at least one mode without vibration reduction device at a position where the vibration reduction direction is to be provided, during intended use of the structure, where Mjj is a modal mass of the structure in which at least one mode is present, and

[0008] A 1j specifies a maximum vibration amplitude in at least one mode during intended use of the structure with the vibration reduction device at the position where the vibration reduction direction is to be provided.

[0009] The at least one mode of the structure is a vibration, in particular a natural vibration, of the structure in which the structure can vibrate and / or be excited. Furthermore, the modal mass of the structure in the at least one mode is a mass of the structure that vibrates, moves, and / or is excited to vibrate in the respective mode.

[0010] In one embodiment, continuous, impact-based momentum exchange, achieved through essentially elastic impacts, can particularly effectively prevent or at least reduce, preferably significantly reduce, structural vibrations. In particular, in one embodiment, the vibration amplitudes of the structure can be significantly reduced with a comparatively low total mass of the at least one body, without requiring the body(s) to be located at the point of maximum mode amplitude. Depending on the design of the specific structure, e.g., a bridge, this may sometimes be difficult or impossible to implement due to geometric or structural limitations.

[0011] By enabling the momentum exchange between the structure and the at least one body via the housing, i.e., between the structure and one or more bodies via the housing in whose cavity the at least one body is arranged, to take place through essentially elastic collisions, in particular with at most 20%, preferably at most 10%, particularly preferably at most 5% energy dissipation per period of the vibration relative to the kinetic energy associated with the vibration, e.g., through friction, vibrations of the structure can be reduced particularly effectively in one embodiment with only small additional masses of the body(s).

[0012] In some embodiments, the vibration damping device has several of the described cavities, particularly closed ones, and several of the described bodies. The present description of "at least one" cavity and "at least one" body can accordingly apply to each cavity and each body of the vibration damping device.

[0013] In some designs, the number of cavities and / or bodies is, for example, 1, 2, 3, 4, 5, 10, 20, 100, 150, 200 or more, or lies in a range between 1 to 300, 1 to 200, 1 to 150, 1 to 100, 1 to 50, 1 to 30, 2 to 10 or 5 to 30.

[0014] Each cavity of the vibration damping device contains exactly one body.

[0015] The essentially elastic impacts can occur between metallic and / or ceramic contact or impact surfaces of the respective body and the respective cavity or housing. In one embodiment, the provision of the vibration reduction device reduces the maximum vibration amplitude in at least one mode by at least 5%, 20%, 30%, 40%, or 50% compared to the vibration amplitude in at least one mode without the vibration reduction device at the position where the vibration reduction direction is to be provided, during intended use of the structure.

[0016] The structure is a rotor or guide vane of an aircraft engine, a part or section thereof, or a part or section in contact with it.

[0017] In one embodiment, the total mass of the at least one body, in particular of all bodies of the vibration damping device taken together, is at least 100 times, preferably at least 1000 times, and in particular at least 10,000 times smaller than the modal mass of the structure oscillating in the respective mode, and / or the modal mass oscillating in the respective mode is at most 200,000 times, preferably at most 100,000 times, and in particular at most 50,000 times larger than the total mass of the at least one body. There is an embodiment of the present invention for each combination of these upper and lower limits.

[0018] In one embodiment, the at least one vibration damping device is arranged on the structure only in those areas where the vibration amplitude in the at least one mode without a vibration damping device in the respective area is at least 0.1%, preferably at least 1%, and / or at most 100%, 50%, 20%, 10%, 5%, 1%, 0.5%, 0.2% of the maximum vibration amplitude in the at least one mode without a vibration damping device in the respective area. There is an embodiment of the present invention for each combination of these upper and lower limits.

[0019] In one embodiment, the at least one body comprises an ellipsoid, in particular a sphere, a cylinder and / or a cuboid.

[0020] In one embodiment, the range of motion of at least one body, in particular of all bodies, in at least one direction, in particular in all directions, is at most twice, preferably at most once, in particular at most 0.5 times, a cross-sectional dimension of the body, in particular a maximum dimension, and / or at least 0.05 times, preferably at least 0.1 times, in particular at least 0.2 times, a cross-sectional dimension of the body, in particular a maximum dimension. There is an embodiment of the present invention for each combination of these upper and lower limits.

[0021] In one embodiment, the structure is a turbine blade with a blade root, a connecting piece for connection to a blade, an upper shroud arranged on the connecting piece, and a lower shroud connecting the blade root and the connecting piece, wherein the at least one vibration damping device is provided in or on the lower shroud and / or in or on the upper shroud and / or in or on the connecting piece.

[0022] In one embodiment, the at least one body, in particular all bodies or the plurality of all bodies, has a metallic or ceramic surface and the at least one cavity, in particular all cavities, is bounded by metallic or ceramic surfaces, so that the impact contacts take place between metal and metal, between ceramic and ceramic or between metal and ceramic, or the body(s) are arranged in the respective cavity to perform such, in particular essentially elastic, impact contacts.

[0023] Further advantageous embodiments of the present invention will become apparent from the following description of preferred embodiments. These are shown, in part schematically: Fig. 1 shows an arrangement according to an embodiment of the present invention; Fig. 2 shows possible positions of a vibration reduction device on a turbine blade; and Figs. 3 and 4 show the effect and effectiveness of vibration reduction by an arrangement according to an embodiment of the present invention.

[0024] Fig. 1 shows an arrangement 10 according to an embodiment of the present invention.

[0025] The arrangement 10 has a vibratory structure 12, which is in Fig. 1 shown only in sections, and includes a vibration reduction device designed to at least reduce vibration of structure 12.

[0026] The vibration reduction device comprises a housing having a cavity 14, in the illustrated embodiment a closed cavity 14, which is formed by the structure 12 and encloses or defines the cavity 14, and a body 16, which may, for example, be made of metal or ceramic or be formed of metal or ceramic, and is arranged in the cavity 14 such that it can move freely with play in at least one direction j, as illustrated by the double arrow P1 shown in the cavity 14.

[0027] At the in Fig. 1 In the embodiment shown, the body 16 is spherical and the cavity 14 is cuboidal. In other embodiments not shown, the body 16 can also have the shape of an ellipse, a cylinder and / or a cuboid, and the cavity 14 can be cylindrical.

[0028] Furthermore, in other embodiments not shown, the arrangement can comprise several housings, each formed by or attached to or connected with the structure 12, and each housing enclosing or defining a cavity 14 in which at least one body 16 is arranged. The individual cavities 14 and the corresponding bodies 16 can be designed such that the bodies 16 arranged in different cavities 14 can move freely in different directions with some play.

[0029] Structure 12 is at least a part or section of a rotor or guide vane of an aircraft engine, a part or section in contact with it.

[0030] Structure 12 exhibits at least one mode, or vibration mode, or natural frequency, in which structure 12 can be excited to oscillations or vibrations during intended use. In the Fig. 1 In the embodiment shown, when excited in at least one mode, the structure 12 oscillates back and forth along the direction j, as illustrated by the bold double arrow P2 shown on the structure 12.

[0031] The body 16 is arranged in the cavity 14 in such a way that, as long as the structure 12 is excited in the at least one mode, it makes impact contacts with the housing, and thus with the structure 12, at least intermittently, in one embodiment continuously, thereby reducing the maximum vibration amplitude in the mode by at least 50% compared to a case in which no vibration reduction device is provided.

[0032] The movement B of the body 16 in the cavity 14, especially when performing the impact contacts with the housing, is defined by a length L Kav of the cavity 14 in the direction of movement j minus the length L Kör of the body 16 in the direction of movement j.

[0033] In one embodiment, the movement B of body 16 can be chosen such that the following equation is satisfied: 0 , 1 × A 0 j < B < 0 , 95 × A 0 j ,

[0034] Additionally or alternatively, a mass mi of at least one body 16 can be chosen such that the following relation is satisfied: m i < μ × M jj , mit μ = a A 1 j A 0 j 2 , und 0 , 000001 < a < 0 , 0009 , Here, the following terms are used:

[0035] A 0j is a vibration amplitude in the at least one mode without a vibration reduction device at a position where the vibration reduction direction is to be provided, during intended use of the structure 12, Mjj is a modal mass of the structure 12 in the at least one mode, and A lj is a maximum vibration amplitude in the at least one mode during intended use of the structure 12 with the vibration reduction device at the position where the vibration reduction direction is to be provided.

[0036] Fig. 2 shows possible positions for attaching a vibration reduction device to a turbine blade.

[0037] The turbine blade 50 has a blade root 52 and a connecting piece 54 with an upper shroud 58 arranged thereon for connection to a blade (not shown), wherein the blade root 52 and the connecting piece 54 are connected to each other via a lower shroud 56. To reduce vibrations of the turbine blade 50, one or more vibration damping devices, each having a housing with a cavity 14 and a body 16 arranged therein, can be provided at different positions on the turbine blade 50.

[0038] For example, a vibration damping device can be arranged in or on the lower cover sheet 56 at position PO1 and / or position PO2. Additionally or alternatively, a vibration damping device can be provided in the connecting piece 54 at position PO3. Additionally or alternatively, vibration damping devices can be provided in or on the upper cover strip 58 at positions PO4, PO5 and / or PO6.

[0039] The effect and effectiveness of vibration reduction using shock contacts and impulse transfers with the vibration reduction device is demonstrated by the Fig. 3 and 4 explained in more detail which ones show experimentally confirmed behavior.

[0040] Fig. 3a This shows vibration profiles, i.e., amplitude-frequency profiles, for a vibrating structure without a vibration damping device (profile 18), with a vibration damping device with a body 16 of mass 1 g (profile 20), with a vibration damping device with a body 16 of mass 2.5 g (profile 22), with a vibration damping device with a body 16 of mass 3 g (profile 24), and with a vibration damping device with a body 16 of mass 4 g (profile 26). The clearance B is 0.2 mm in profiles 20–26.

[0041] Fig. 3a This clearly shows that, in particular, continuous impact contacts of bodies 16 with larger masses (trajectories 22, 24, 26), the vibration amplitude of the mode can be significantly reduced compared to such arrangements without impact contacts or impact contacts of a body 16 with a small mass (trajectories 18, 20).

[0042] Fig. 3b shows for the example of the Fig. 3a the dependence of the vibration amplitude reduction on the mass of the body 16 each for a movement range of 1.0 mm (curve 28), 0.3 mm (curve 30) and 0.2 mm (curve 32).

[0043] Fig. 4a shows vibration profiles for a vibrating structure 12 without a vibration reduction device (profile 34) and with a vibration reduction device with a body 16 of mass 2 g, each with a movement range B of 0.2 mm (profile 36), 0.3 mm (profile 38) and 1.0 mm (profile 40).

[0044] Fig. 4b shows for the example of the Fig. 4a the dependence of the amplitude reduction on the movement B of body 16 of mass 2 g (curve 42).

[0045] In the examples of Fig. 3 and 4The impacts are essentially elastic and energy dissipation through friction is low, in particular less than 5% per period of the kinetic energy of the body associated with the oscillation.

[0046] Although exemplary embodiments were explained in the preceding description, it should be noted that a multitude of modifications are possible. Furthermore, it should be emphasized that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or structure in any way. Rather, the preceding description provides the skilled person with a guideline for implementing at least one exemplary embodiment, whereby various modifications, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as defined by the claims and these equivalent combinations of features. The scope of protection is defined by the accompanying claims. Reference symbol list

[0047] 10 Arrangement for vibration reduction 12 Structure 14 Cavity 16 Body 18 Amplitude-frequency curve without vibration reduction device 20 Amplitude-frequency curve with body of mass 1 g 22 Amplitude-frequency curve with body of mass 2.5 g 24 Amplitude-frequency curve with body of mass 3 g 26 Amplitude-frequency curve with body of mass 4 g 28 Amplitude-mass curve for a movement range of 1.0 mm 30 Amplitude-mass curve for a movement range of 0.3 mm 32 Amplitude-mass curve for a movement range of 0.2 mm 34 Amplitude-frequency curve without vibration reduction device 36 Amplitude-frequency curve with body of mass 2 g and movement range 0.2 mm 38Amplitude-frequency curve with body of mass 2 g and movement range of 0.3 mm 40Amplitude-frequency curve with body of mass 2 g and movement range of 1,0 mm 42 Amplitude-of-motion-gape for body of mass 2 g 50 Turbine blade 52 Blade root 54 Connecting piece 56 Lower cover sheet PO1 Possible position of the vibration damping device on a turbine blade PO2 Possible position of the vibration damping device on a turbine blade PO3 Possible position of the vibration damping device on a turbine blade PO4 Possible position of the vibration damping device on a turbine blade PO5 Possible position of the vibration damping device on a turbine blade PO6 Possible position of the vibration damping device on a turbine blade,

Claims

1. Arrangement (10) for reducing vibration of a vibratable structure (12), which structure (12) is a rotor blade or guide vane of an aircraft engine, a part or portion thereof or a part or portion in contact therewith, comprising: - a structure (12), which structure (12) is a rotor blade or guide vane of an aircraft engine, a part or portion thereof or a part or portion in contact therewith, having at least one mode in at least one direction (j), and - at least one vibration reduction device which comprises at least one housing having a cavity (14), in particular a closed cavity (14), which housing is formed by the structure (12) or is provided on the structure (12), and comprises at least one body (16), wherein exactly one body is arranged in each of the at least one cavity, which body is arranged in the at least one cavity (14), for executing substantially elastic impact contacts with the housing, in such a way that, as long as the structure (12) is excited in the at least one mode in the at least one direction (j), said body executes substantially elastic impact contacts with the housing at least temporarily, in particular continuously, wherein a) for a movement play B of the at least one body (16) in the at least one direction (j) in the at least one cavity (14), the following applies: 0.1 x A 0 j < B < 0.95 x A 0 j , and b) for a mass mi of the at least one body (16), the following applies: m i < μ × M jj , with μ = a A 1 j A 0 j 2 , and 0.000001 < a < 0.0009 , wherein A0j indicates a vibration amplitude in the at least one mode without the vibration reduction device in a position in which the vibration reduction direction is to be provided, when the structure (12) is used as intended, wherein Mjj is a modal mass of the structure (12) in the at least one mode, and A1j indicates a maximum vibration amplitude in the at least one mode when the structure (12) is used as intended with the vibration reduction device in the position in which the vibration reduction direction is to be provided.

2. Arrangement (10) according to the preceding claim, wherein the provision of the vibration reduction device reduces a maximum vibration amplitude in the at least one mode by at least 5%, 20%, 30%, 40% or 50% compared to the vibration amplitude in the at least one mode without the vibration reduction device in the position in which the vibration reduction device is to be provided, when the structure (12) is used as intended.

3. Arrangement (10) according to either of the preceding claims, wherein the total mass of the at least one body (16), in particular of all bodies of the vibration reduction device, is at least 100 times, preferably at least 1000 times, in particular at least 10,000 times, smaller than the modal mass of the structure (12) vibrating in the relevant mode, and / or the modal mass vibrating in the relevant mode is at most 200,000 times, preferably at most 100,000 times, in particular at most 50,000 times greater than the total mass of the at least one body (16).

4. Arrangement (10) according to any of the preceding claims, in which the at least one vibration reduction device is or are arranged on the structure (12) only in regions in which the vibration amplitude in the at least one mode without the vibration reduction device in the relevant region is at least 0.1%, preferably at least 1% and / or at most 100%, 50%, 20%, 10%, 5%, 1%, 0.5%, 0.2% of the maximum vibration amplitude in the at least one mode without the vibration reduction device in the relevant region.

5. Arrangement (10) according to any of the preceding claims, wherein the body or bodies (16) comprise or are ellipsoids, in particular spheres, cylinders and / or cuboids.

6. Arrangement (10) according to any of the preceding claims, wherein the movement play (g) of at least one of the one or more bodies (16), in particular of all bodies (16), in at least one direction (j), in particular in all directions, is at most 2 times, preferably at most 1 times, in particular at most 0.5 times, a, in particular maximum, cross-sectional dimension of the body (16) and / or at least 0.05 times, preferably at least 0.1 times, in particular at least 0.2 times, a, in particular maximum, cross-sectional dimension of the body (16).

7. Arrangement (10) according to any of the preceding claims, wherein the structure (12) is a turbine blade (50) with a blade root (52), a connecting piece (54) for connection to an airfoil, an upper shroud arranged on the connecting piece (54), and a lower shroud (56) which connects the blade root (52) and the connecting piece (54), and the vibration reduction device is provided in or on the lower shroud (56) and / or in or on the upper shroud (56) and / or in or on the connecting piece (54).

8. Arrangement (10) according to any of the preceding claims, wherein the at least one body (16) comprises a metal or ceramic surface and the at least one cavity (14) is delimited by metal or ceramic surfaces, so that the impact contacts take place between metal and metal, between ceramic and ceramic or between metal and ceramic.