A kind of impeller partial vibration self-adapting suppression device and a centrifugal impeller

Abstract

The application discloses a kind of localized vibration self-adaptive suppression device and a kind of centrifugal impeller, the device includes piezoelectric sheet and permanent magnet;Piezoelectric sheet is connected with resistance, resistance is located in the magnetic field range of permanent magnet;The current flowing through the resistance generates ampere force opposite to the direction of local vibration under the magnetic field of the permanent magnet when the device works.When local vibration occurs, mechanical force acts on piezoelectric sheet, alternating current is generated on piezoelectric sheet, output to resistance, realize the consumption of electric energy, simultaneously, the alternating current generated under the action of the magnetic field of permanent magnet, will generate ampere force opposite to the direction of local vibration, the ampere force can effectively offset the mechanical force of impeller local vibration, realize impeller vibration localized suppression.In addition, the charge amount generated by electromechanical coupling is proportional to the amplitude of impeller local vibration, i.e.the size of ampere force is proportional to the mechanical force of impeller local vibration, so it can be self-adaptively adjusted, effectively realize impeller vibration localized suppression.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of impeller machine vibration suppression, and relates to a kind of impeller localized vibration self-adaptive suppression device and a kind of centrifugal impeller. BACKGROUND

[0002] Centrifugal compressor (or compressor) is an important equipment in aerospace, metallurgy, power, petroleum, chemical industry and other industrial fields. For a long time, the vibration problem of large-scale, high-speed centrifugal impeller has been affecting the safe and reliable operation of the compressor. As the key component of the compressor, whether the impeller can run safely for a long time is very important to the whole unit. If the impeller has a problem during operation, it may cause economic loss or even equipment scrap and personnel injury. In recent years, with the rapid development of national economy and aerospace field, the performance of the unit is continuously improved, and the centrifugal compressor is developing towards large-scale, high-speed and high pressure ratio. These changes improve the fluid performance of the impeller, but also bring many new problems in structure, i.e. with the increase of the size of the impeller, the excitation force of the fluid is more serious, and higher requirements are put forward for the reliability of the impeller.

[0003] The periodic symmetric structure of the impeller has unique mechanical properties different from the non-periodic symmetric structure, i.e. the characteristics of frequency passband and forbidden band. When the excitation frequency is in the passband region, the vibration mode and energy are uniformly distributed in the whole structure. When the excitation frequency is in the forbidden band region, the wave amplitude and energy will not spread throughout the structure, but will be mainly limited in a local area of the structure, resulting in energy accumulation. In the study of periodic structure vibration theory and a large number of engineering calculations, it is usually assumed that the system has ideal regularity. However, due to the influence of errors caused by processing and manufacturing and other factors, the actual structure often has some degree of irregularity, uncertainty, defects or mistuning. Once the structure has mistuning, under certain conditions, a small amount of mistuning will cause a sharp change in the vibration mode of the structure, and the vibration of these modes is mainly limited in each local area of the structure, which will completely change the calculation results in the ideal case. This is the phenomenon of localized vibration of the structure, and its greatest harm is to cause high-cycle fatigue failure (HCF) to occur, which may lead to blade fracture and rotor sudden imbalance, resulting in shutdown.

[0004] In recent years, many scholars have studied the vibration localization of the impeller. Their research mainly focuses on the mechanism, conditions and influence of vibration localization, and there is less research on the control of localized vibration. Some scholars have proposed a calculation model containing a friction damper structure, which reduces the vibration amplitude of the locally vibrating blade through dry friction dissipation. Although this method can reduce the amplitude of the locally vibrating blade, it changes the original structure of the impeller and may have new effects on the impeller. SUMMARY

[0005] In view of the problems in the prior art, the application provides a centrifugal impeller and a local vibration self-adaptive suppression device of an impeller, so as to solve the technical problems of blade fracture and rotor sudden imbalance caused by local vibration of the impeller in the prior art.

[0006] The application is realized by the following technical scheme:

[0007] The local vibration self-adaptive suppression device of the impeller comprises a piezoelectric sheet and a permanent magnet.

[0008] When the device works, the current flowing through the resistor generates an ampere force opposite to the direction of the local vibration under the magnetic field of the permanent magnet.

[0009] Preferably, the piezoelectric sheet is a piezoelectric ceramic double crystal sheet.

[0010] Preferably, the electromechanical coupling coefficient of the piezoelectric ceramic double crystal sheet is 0.7-0.8.

[0011] Preferably, the permanent magnet is a rare earth permanent magnet material.

[0012] Preferably, the rare earth permanent magnet material is a neodymium iron boron permanent magnet material.

[0013] The centrifugal impeller comprises the local vibration self-adaptive suppression device of the impeller.

[0014] Preferably, the blade of the centrifugal impeller is provided with grooves on both sides, and the piezoelectric sheet is arranged at the grooves.

[0015] Preferably, the overall height of the local vibration self-adaptive suppression device of the impeller is not greater than the depth of the grooves.

[0016] Preferably, the piezoelectric sheets are symmetrically arranged on all the blades of the centrifugal impeller.

[0017] The centrifugal compressor comprises the centrifugal impeller.

[0018] Compared with the prior art, the application has the following beneficial technical effects:

[0019] The application discloses a local vibration self-adaptive suppression device of an impeller, which comprises a piezoelectric sheet and a permanent magnet; the piezoelectric sheet is provided with a resistor, and the permanent magnet is arranged close to the resistor; when the device works, the current flowing through the resistor generates an ampere force opposite to the direction of local vibration under the magnetic field of the permanent magnet. During use, when local vibration occurs, mechanical force acts on the piezoelectric sheet; when the piezoelectric material is subjected to external force in a certain direction, polarization phenomenon occurs inside the piezoelectric material, meanwhile, equal and opposite charges are generated on the upper and lower surfaces of the piezoelectric material, and the generated charge is proportional to the applied external force; therefore, when mechanical vibration occurs, alternating current is generated on the piezoelectric sheet, and is output to the resistor to realize consumption of the alternating current. Meanwhile, the alternating current generated under the magnetic field of the permanent magnet generates an ampere force opposite to the direction of local vibration, which can effectively offset the mechanical force of the local vibration of the impeller, realizing local vibration suppression of the impeller; since the generated charge is proportional to the applied external force, that is, the size of the ampere force is proportional to the mechanical force of the local vibration of the impeller, the local vibration suppression of the impeller can be self-adaptively adjusted and effectively realized.

[0020] Further, the piezoelectric sheet is a piezoelectric ceramic double sheet, the electromechanical coupling coefficient of the piezoelectric ceramic double sheet is high, mechanical energy can be fully converted into electric energy, and the generated ampere force can effectively suppress local vibration.

[0021] Further, the electromechanical coupling coefficient of the piezoelectric ceramic double sheet is 0.7-0.8, mechanical energy can be fully converted into electric energy, and the generated ampere force can effectively suppress local vibration.

[0022] Further, the permanent magnet is a rare earth permanent magnetic material, and the rare earth permanent magnetic material is a neodymium iron boron permanent magnetic material; the magnetic performance of the permanent magnetic material is stable, the corrosion resistance is high, the product size precision is high, the shape freedom degree is large, and a stable magnetic field can be formed.

[0023] In addition, the application further discloses a centrifugal impeller, and the blade of the centrifugal impeller is provided with the local vibration self-adaptive suppression device.

[0024] Further, the two sides of the blade of the centrifugal impeller are provided with grooves, and the piezoelectric sheet is arranged at the grooves; the groove type design can not change the original aerodynamic performance of the impeller, so that the overall coordination of the impeller is maintained.

[0025] Further, the overall height of the local vibration self-adaptive suppression device of the impeller is not greater than the depth of the groove, and the structure effectively reduces the influence of the device on the original aerodynamic performance of the blade.

[0026] Further, the piezoelectric sheets are symmetrically arranged on all the blades of the centrifugal impeller, and the overall coordination of the impeller can be fully maintained. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 It is a structural schematic diagram of a partial vibration self-adaptive suppression device for an impeller in the present application.

[0029] Figure 2 It is a schematic diagram of polarization of piezoelectric material under the action of external mechanical force.

[0030] Figure 3 It is a structural schematic diagram of a partial vibration self-adaptive suppression device for an impeller in the present application arranged on the blade.

[0031] Figure 4 It is a structural schematic diagram of a partial vibration self-adaptive suppression device for an impeller in the present application arranged on the blade.

[0032] Figure 5 It is a structural schematic diagram of an ampere force generated when the blade locally vibrates: A, the blade vibrates to the left, B, the blade vibrates to the right.

[0033] In which: 1, piezoelectric sheet, 2, permanent magnet, 3, resistor, 4, blade, 5, groove. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, not all of the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] It should be noted that: similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0037] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product of the present application is used, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the device or element indicated to have a specific orientation, to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0038] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0039] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] The present application will be described in further detail below with reference to the accompanying drawings:

[0041] As shown in Figure 1 The present application provides a kind of impeller partial vibration self-adapting inhibiting device, including piezoelectric sheet 1 and permanent magnet 2;Resistance 3 is connected on the piezoelectric sheet 1, and the resistance 3 is located in the magnetic field range of permanent magnet 2;When the device works, the current flowing through the resistance 3 generates ampere force opposite to the direction of local vibration under the magnetic field of the permanent magnet 2.

[0042] In a preferred embodiment of the present application, the piezoelectric sheet 1 is a piezoelectric ceramic double wafer, and the electromechanical coupling coefficient of the piezoelectric ceramic double wafer is high, which can fully convert mechanical energy into electrical energy, so that the generated ampere force can effectively suppress local vibration. More preferably, the electromechanical coupling coefficient of the piezoelectric ceramic double wafer is 0.7-0.8, which can fully convert mechanical energy into electrical energy, so that the generated ampere force can effectively suppress local vibration. The electromechanical coupling coefficient refers to the interaction strength of piezoelectric material and piezoelectric effect, and is a physical quantity describing the coupling degree between mechanical strain and charge induction of piezoelectric ceramic material and device, and its expression is:

[0043]

[0044] In the formula, U I is the interaction energy density, U M is the elastic energy density, U E is the dielectric energy density. The piezoelectric ceramic bimorph used in the present application has a high electromechanical coupling coefficient.

[0045] The permanent magnet 2 is a rare earth permanent magnet material. The rare earth permanent magnet material is a neodymium iron boron permanent magnet material, which has stable magnetic properties, strong corrosion resistance, high product size precision, large shape freedom, and can form a stable magnetic field.

[0046] Piezoelectric materials are generally divided into piezoelectric single crystals, polycrystalline piezoelectric ceramics, and high molecular piezoelectric materials, and the basic performance description parameters include dielectric constant, elastic coefficient, and piezoelectric constant, electromechanical coupling coefficient, etc. From the application point of view, piezoelectric materials for different purposes have different requirements for the above parameters. For the piezoelectric material of the present application, the efficiency of electromechanical coupling is very critical. Therefore, a piezoelectric ceramic bimorph with a large electromechanical coupling coefficient can be selected to realize more efficient conversion of mechanical energy and electrical energy of the local vibration impeller.

[0047] The piezoelectric effect includes positive piezoelectric effect and inverse piezoelectric effect. When a piezoelectric material is subjected to an external force in a certain direction, polarization will occur inside, and equal and opposite charges will be generated on its upper and lower surfaces, and the amount of charge generated is proportional to the applied external force; when the external force is removed, the piezoelectric material returns to the initial uncharged state, which is called positive piezoelectric effect, and the principle diagram is shown in Figure 2 .

[0048] The present application also discloses a centrifugal impeller comprising the impeller local vibration self-adaptive suppression device.

[0049] As shown in Figure 3 , in a preferred embodiment, the blades 4 of the centrifugal impeller are provided with grooves 5 on both sides, and the piezoelectric sheets are arranged in the grooves. This groove design not only facilitates the fixation and installation of the piezoelectric sheets, but also does not change the original aerodynamic performance of the impeller, so that the overall coordination of the impeller is maintained.

[0050] At the same time, the overall height of the impeller local vibration self-adaptive suppression device is not greater than the depth of the groove, and this structure can effectively reduce the influence of the device on the original aerodynamic performance of the blades.

[0051] In addition, as shown in Figure 4 , the piezoelectric sheets are symmetrically arranged on all the blades of the centrifugal impeller, which can further improve the overall coordination of the impeller.

[0052] Specifically, the present application designs grooves 5 of piezoelectric sheets on both sides of all blades 4, and sticks piezoelectric sheets 1 in all grooves 5, namely, forms a piezoelectric bimorph, so as to realize electromechanical coupling; uses a wire connection as an electromechanical coupling electric energy output source on both sides of the arranged piezoelectric sheet 1, and the output current is an alternating current; constructs a circuit at both ends of the obtained alternating current source, tightly sticks an electric wire on the blade 4, and simultaneously connects a resistor 3 in series, so as to realize consumption of electric energy; according to the current direction of the electric wire, places a permanent magnet 2, preferably a micro permanent magnet, in the electric wire area to exert a magnetic field in a specific direction, so as to generate an ampere force capable of inhibiting impeller vibration. The groove type design can not change the original aerodynamic performance of the impeller, and installation on all blades can maintain the overall coordination of the original impeller. The locally vibrating impeller in the structure is reciprocating vibration, and alternating current with a direction changing with the vibration direction is generated on the piezoelectric sheet. The thin wire is tightly stuck on the blade in order to realize that the ampere force generated by the energized conductor under the action of the magnetic field acts on the locally vibrating impeller, so as to inhibit the vibration. The resistor is used to consume the electric energy converted under the positive piezoelectric effect. The exerted magnetic field can make the direction of the ampere force acting on the impeller opposite to the vibration direction, so as to inhibit the vibration. The mechanism of action is shown in Figure 5 When the blade vibrates to the left, the current direction is downward, and under the action of the micro magnetic field, the direction of the ampere force is right. When the blade vibrates to the right, the alternating current direction changes, and under the action of the micro magnetic field, the direction of the ampere force is left.

[0053] The self-adaptive method for realizing impeller vibration localization inhibition and energy dissipation disclosed in the present application is based on the traditional vibration electromechanical coupling design, combines the basic principle that the energized conductor is subjected to the ampere force in the magnetic field, and inhibits the vibration and dissipates the energy of the impeller generating vibration localization. The piezoelectric sheets are stuck on both sides of the grooved impeller, once the impeller generates vibration localization, the energy is concentrated on a blade, at this time, the blade has a larger amplitude, and exerts force on the piezoelectric sheets on both sides. Once the piezoelectric material is subjected to external stress, the geometric shape of the internal crystal atomic structure of the material will change, the electric charge of the material surface is polarized and forms an electric field, and mechanical energy is converted into electric energy. The blade vibration is reciprocating vibration, the output current is alternating current, the wire closely stuck on the blade is connected with the resistor to form a loop, and a stable magnetic field is matched. Under the action of the resistor, the energy of the mechanical energy converted into electric energy is dissipated, and under the action of the magnetic field, the locally vibrating impeller is inhibited under the action of the ampere force, and the amplitude is reduced.

[0054] The vibration localization mechanism of the present application is as follows: the mechanism of vibration localization is explained by using wave propagation, and the forced response of a given blade is assumed to be the superposition of waves propagating in the circumferential direction of the blade-disk structure system at different speeds. If the system is linear, the mechanism of localization can be discussed by analyzing the propagation of a single wave. The propagation of a certain vibration wave from one blade to another through the disk is simulated as the propagation from one layer to another through a "multi-layer medium", where the wave speed c in the medium corresponds to the physical property H(ω) (transfer function) of the blade, because the propagation of the vibration wave along the disk is determined by the frequency ω, and its effect on the wave can be better defined by the corresponding transfer function H(ω), so there is a corresponding relationship H(ω)→c.

[0055] If the system is harmonic, all the blades (corresponding to all the layers) are the same, and the propagation of the vibration wave is not affected by the interface between the layers. If the system is mistuned, the blades (corresponding to the layers) are inconsistent, and the vibration wave is partially transmitted and partially reflected at the interface. For the reflected component, its amplitude generally increases with the inconsistency of the properties of the two layers forming the interface (i.e. the frequency response functions of the two blades), and if it is on a highly reflective interface (i.e. two adjacent blades with a large difference in the frequency response function), the vibration wave can be suppressed in a few layers (blades). Obviously, the vibration response of some blades corresponding to the suppressed vibration wave is very large, which is the mechanism of vibration localization.

[0056] The Ampere force in the present application is described in detail as follows: the force acting on a straight conductor with a current I and a length L in a uniform magnetic field B. The size of the Ampere force is F=ILBsinα, where α is the included angle between the current direction and the magnetic field direction. The direction of the Ampere force is determined by the left-hand rule. For the force acting on a current in a non-uniform magnetic field, the current can be divided into many current elements IΔL, and the magnetic field B at each current element can be regarded as a uniform magnetic field, and the Ampere force of each current element is ΔF=IΔL·Bsinα. The sum of the Ampere force vectors of the current elements is the force acting on the entire current. It should be noted that when the current direction is the same as or opposite to the magnetic field direction, i.e. α=0 or π, the current is not affected by the magnetic field force. When the current direction is perpendicular to the magnetic field direction, the Ampere force acting on the current is the largest, F=BIL. B is the magnetic induction intensity, I is the current intensity, and L is the length of the conductor perpendicular to the magnetic induction lines. The essence of the Ampere force is the resultant force of the Lorentz forces acting on the directional moving charges forming the current.

[0057] The present application also discloses a centrifugal compressor, which comprises the centrifugal impeller of the present application.

[0058] The piezoelectric sheet is installed in the slotted impeller, a microcircuit and a magnetic field are constructed, the scheme is reasonable, the structure is simple, and the microcircuit is easy to realize. The conversion of the local vibration energy and the electric energy is completed by using the electromechanical coupling, the vibration suppression and the energy dissipation are completed according to the basic principle that the current conductor is subjected to the Ampere force in the magnetic field, the problem of the vibration localization of the impeller can be effectively solved. In addition, the element used is a micro element, and the piezoelectric sheet and the like are installed in the slotted impeller, the original structure of the impeller is ensured, the flow condition inside the impeller is not affected, no new aerodynamic mistuning is introduced, and the aerodynamic performance of the impeller is ensured. The application has self-adaptability. When the localization phenomenon of the impeller is stronger, the local blade vibration energy is larger, the amplitude is larger, the electric energy generated by the electromechanical coupling is more, the current in the loop is larger, the Ampere force in the magnetic field is larger, and the suppression effect is more significant. The application has guiding significance for the vibration control of the centrifugal impeller. The impeller designed by using the application can well solve the problem of the vibration localization under the mistuned condition, can ensure the safe and reliable long-term operation of the centrifugal impeller unit, and greatly improves the safety of the impeller.

[0059] The above only is the preferred embodiment of the application, and is not used for limiting the application. The application can have various changes and variations for the person skilled in the art. Any modification, equivalent replacement, improvement and the like made in the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A centrifugal impeller, characterized by The invention relates to a centrifugal impeller with partial vibration self-adaptive suppression device. The centrifugal impeller comprises a piezoelectric sheet (1) and a permanent magnet (2), and the piezoelectric sheet (1) is connected with a resistor (3) which is located in the magnetic field of the permanent magnet (2). When the device is in operation, the current flowing through the resistor (3) generates an Ampere force in the opposite direction of the partial vibration under the magnetic field of the permanent magnet (2). Both sides of the blade (4) of the centrifugal impeller are provided with grooves (5), and the piezoelectric sheet is arranged in the grooves. The overall height of the centrifugal impeller with partial vibration self-adaptive suppression device is not greater than the depth of the grooves. The piezoelectric sheets are symmetrically arranged on all the blades of the centrifugal impeller.

2. A centrifugal impeller according to claim 1, characterized in that The piezoelectric sheet (1) is a piezoelectric ceramic double wafer.

3. A centrifugal impeller according to claim 2, wherein The electromechanical coupling coefficient of the piezoelectric ceramic double wafer is 0.7-0.

8.

4. A centrifugal impeller according to claim 1, wherein The permanent magnet (2) is a rare earth permanent magnet material.

5. A centrifugal impeller according to claim 4, wherein The rare earth permanent magnet material is a neodymium iron boron permanent magnet material.

6. A centrifugal compressor characterized by, The invention also relates to a centrifugal impeller comprising any one of the partial vibration self-adaptive suppression devices according to claims 1-5.

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