Floating ring sealing structure, aero-engine and rub-impact risk assessment method of aero-engine

Abstract

The invention relates to the technical field of aero-engines, and particularly provides a floating ring sealing structure, an aero-engine and a rub-impact risk assessment method of the aero-engine. The floating ring sealing structure comprises a casing, a sealing moving ring and a floating ring assembly which are arranged in a nested mode, the floating ring assembly is located between the casing and the sealing moving ring, and the floating ring assembly and the sealing moving ring are in clearance fit and are arranged in a non-centering mode. The floating ring sealing structure is ingenious in design, the non-contact sealing effect is guaranteed, and meanwhile the amount of gas leaked into a bearing cavity can be reduced. In addition, according to the rub-impact risk assessment method for the floating ring sealing structure, main influence factors and a detailed solving process of the floating characteristic of the floating ring assembly are given, and a basis is provided for quantitative analysis of the follow-up characteristic of the floating ring sealing structure; the buoyancy is analyzed by adopting a finite volume method three-dimensional grid, a necessary flow field area is defined, the precision of a calculation result is higher than that of a calculation result adopting an empirical formula, and the calculation efficiency is considered.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft engines, and specifically proposes a floating ring sealing structure, an aircraft engine and a friction risk assessment method thereof. Background Art

[0002] At present, when aircraft engines are working, in order to prevent the leakage of lubricating oil in the bearing cavity and to achieve effective isolation from the external airflow environment, it is necessary to add a sealing structure. Due to the high speed of aircraft engines, in order to prevent excessive wear of the sealing structure, a non-contact sealing structure is usually used, for example, Figure 1 The comb seal structure shown in the figure; wherein, the comb seal assembly b is in radial contact with the casing, and there is a certain gap between the comb seal and the sealing dynamic ring, so the gas pressure outside the bearing cavity is required to be greater than the gas pressure inside the bearing cavity. At this time, part of the gas on the outside can flow into the bearing cavity, thereby achieving the purpose of preventing the lubricating oil in the bearing cavity from leaking out.

[0003] However, affected by the actual working environment of the aircraft engine, the temperature of the gas outside the bearing cavity is generally higher. If too much gas flows into the bearing cavity, it may cause the temperature inside the bearing cavity to rise, causing the working environment of the bearing to deteriorate. On the other hand, excessive gas leakage will also lead to reduced efficiency of the aircraft engine.

[0004] Therefore, on the premise of meeting the lubricating oil sealing requirements, the non-contact sealing structure should also minimize the amount of gas leaking into the bearing cavity. Summary of the invention

[0005] The purpose of the present invention is to solve at least part of the technical problems mentioned above, and this purpose is achieved through the following technical solutions:

[0006] In a first aspect, the present application proposes a floating ring sealing structure, which includes a nested casing, a sealing dynamic ring and a floating ring assembly, wherein the floating ring assembly is located between the casing and the sealing dynamic ring, the floating ring assembly and the sealing dynamic ring are gap-matched and the two are non-centeringly arranged.

[0007] In some embodiments, the floating ring sealing structure also includes an elastic member and a gasket, the elastic member is circumferentially arranged between the casing and the sealing dynamic ring, and the elastic member is located on one axial side of the floating ring assembly; a gasket is provided on one or both axial sides of the elastic member, and the gasket is circumferentially arranged between the casing and the sealing dynamic ring.

[0008] In some embodiments, the inner diameter of the elastic member is greater than or equal to the inner diameter of the gasket, and / or the inner diameter of the gasket is greater than or equal to the inner diameter of the floating ring assembly.

[0009] In some embodiments, the elastic member is a wave spring.

[0010] In some embodiments, the floating ring sealing structure further includes a retaining ring, which is circumferentially disposed between the casing and the sealing dynamic ring, and is located on a side of the elastic member axially away from the floating ring assembly.

[0011] In some embodiments, the floating ring assembly includes a graphite ring and a graphite ring outer ring, and the graphite ring outer ring is inlaid on the periphery of the graphite ring.

[0012] In a second aspect, the present invention provides an aircraft engine, which includes the floating ring seal structure of the first aspect.

[0013] In some embodiments, the aircraft engine also includes a concentrically arranged gas turbine rotating part, a power turbine rotating part and a compressor rotating part. The gas turbine rotating part and the compressor rotating part are rotatably arranged through a gas generator rotor drive shaft, and the power turbine rotating part is rotatably arranged through a power turbine rotor drive shaft. The gas generator rotor drive shaft is nested on the outside of the turbine rotor drive shaft; floating ring sealing structures are respectively provided on both axial sides of the power turbine rotating part, and a bearing cavity is formed between the two floating ring sealing structures. At least two bearings are provided in the bearing cavity, and the bearing sleeves are respectively provided on the power turbine rotor drive shaft and the gas turbine rotor drive shaft.

[0014] In some embodiments, the floating ring sealing structures on both axial sides are single-stage floating ring sealing structures and / or double-stage floating ring sealing structures.

[0015] In a third aspect, the present invention provides a floating ring seal structure collision risk assessment method, using the floating ring seal structure of the first aspect, comprising the following steps:

[0016] Analyze the possible unbalanced response of the aircraft engine rotor, and further analyze the maximum response of the seal dynamic ring on this basis;

[0017] The flow field boundary between the floating ring assembly and the sealing dynamic ring is obtained by analysis, and a CFD numerical calculation model is established to calculate the buoyancy of the floating ring assembly at different times.

[0018] Calculate the elastic force of the wave spring and the friction between the floating ring assembly, the casing and the gasket;

[0019] Based on the analysis of the sealing dynamic ring response, the buoyancy and friction force on the graphite ring, an equivalent calculation model of the dynamic characteristics of the rotor-floating ring sealing structure is established to analyze the relative motion relationship between the two and evaluate the risk of friction.

[0020] The technical solution provided by the present invention has at least the following technical effects:

[0021] In the present invention, the floating ring seal structure is cleverly designed with low cost. It can achieve the non-contact sealing effect with an extremely streamlined structure while reducing the amount of gas leaking into the bearing cavity. In addition, the floating ring seal structure collision risk assessment method provided by the present invention gives the main influencing factors of the floating ring assembly's floating characteristics, as well as a detailed solution process, which provides a basis for quantitatively analyzing the follow-up characteristics of the floating ring seal structure; the finite volume method is used to analyze the buoyancy of the three-dimensional grid, and the necessary flow field calculation area is clarified. The calculation result is more accurate than that of the empirical formula, and the calculation efficiency is taken into account; considering the unbalanced distribution range of the rotor under service conditions, and using the response analysis results of the sealing dynamic ring confirmed by the model, the collision risk assessment of the floating ring seal structure of the aircraft engine is more in line with engineering applications; an equivalent calculation model of the dynamic characteristics of the rotor-floating ring seal structure is established, and the three-dimensional CFD steady-state flow field calculation results are combined with the classical vibration calculation process through the analysis of the follow-up characteristics of the floating ring seal structure and the collision risk assessment, and the shortcomings of low efficiency and easy divergence of the unsteady flow field calculation are overcome with high calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to better combine the contents shown in the drawings of the specification with the contents described in the specific implementation methods, the drawings of the specification are briefly introduced below. It can be understood that the drawings of the specification mentioned below only schematically show some embodiments of the relevant technical solutions and the technical solutions of the present invention. Without paying creative labor, those skilled in the art can also make drawings showing other embodiments.

[0023] Specifically, the annotations of the drawings in the specification are as follows:

[0024] Figure 1 It is a structural schematic diagram of the comb tooth sealing structure before improvement;

[0025] Figure 2 It is a structural schematic diagram of a floating ring sealing structure according to some embodiments of the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of an aircraft engine according to some embodiments of the present invention;

[0027] Figure 4 for Figure 3 The enlarged schematic diagram of point A in the middle;

[0028] Figure 5 It is an enlarged schematic diagram of the floating ring sealing structure described in some embodiments of the present invention;

[0029] Figure 6 It is a structural schematic diagram of the floating ring sealing structure before floating according to some embodiments of the present invention;

[0030] Figure 7It is a schematic diagram of the structure of the floating ring sealing structure after floating according to some embodiments of the present invention;

[0031] Figure 8 It is a schematic diagram of an equivalent calculation model described in some embodiments of the present invention;

[0032] Fig. 9 It is a schematic diagram of the structure of the elastic member according to some embodiments of the present invention;

[0033] Fig.10 A block diagram of the content of the floating ring seal structure collision risk assessment method described in some embodiments of the present invention;

[0034] Fig.11 It is a schematic diagram of the structure of the flow field area described in some embodiments of the present invention.

[0035] Specifically, the annotations of the accompanying drawings in the specification are as follows:

[0036] 100, aircraft engine; 110, gas turbine rotating parts; 120, power turbine rotating parts; 130, power turbine rotor drive shaft; 140, gas generator rotor drive shaft; 150, compressor rotating parts; 160, casing; 170, sealing dynamic ring; 180, bearing; Q, bearing cavity; F1, gravity; F2, friction force; F3, elastic force; S, sinusoidal excitation; L, flow field area;

[0037] a, floating ring assembly; a1, retaining ring; a2, gasket; a3, elastic part; a4, graphite ring; a5, graphite ring outer ring; b, comb tooth sealing assembly. DETAILED DESCRIPTION

[0038] In order to make the contents of the embodiments of the present invention clearer, the following description will be made in conjunction with the accompanying drawings. It can be understood that the contents mentioned below are only some embodiments of the present invention, and all embodiments are listed in detail. Therefore, without paying creative work, other embodiments obtained based on the following embodiments fall within the protection scope of the present invention.

[0039] It should be understood that the terms used herein are only for the purpose of describing specific embodiments and are not intended to strictly limit the technical solutions unless the context clearly indicates otherwise. For example, the use of "a", "an" and "the" to modify a feature does not exclude that the feature may also be plural in other embodiments.

[0040] It should be understood that the terms "include", "comprises", and "have" are open ended, indicating the presence of the stated features, but not excluding the possibility that the embodiment may have other features. Similarly, the use of the terms first, second, etc. in the text to describe multiple features only means to distinguish one feature from another, and unless the context clearly indicates otherwise, such terms do not imply an order or sequence.

[0041] It should be understood that, unless the context clearly indicates otherwise, the terms "dispose", "connect", and "install" should be understood in a broad sense, for example, they can be fixedly connected, detachably connected, or integrally connected; they can be directly connected or indirectly connected through a medium. For those skilled in the art, the specific meanings of the above terms in the text can be understood according to the specific circumstances.

[0042] In addition, for the convenience of description, the text will use terms of spatial relative relationships to illustrate the position of one feature relative to another feature, for example, "inside", "outside", "end", "side", "top", "middle", "bottom", "high", "low", "axial", "circumferential", "radial", "horizontal", "vertical", "first direction", "second direction", etc. It can be understood that the spatial relative relationship between two features should include other specific situations in addition to those shown in the drawings of the specification.

[0043] The embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0044] First, refer to Figure 2 and Figure 5 , the present application proposes a floating ring sealing structure, which includes a nested casing 160, a sealing dynamic ring 170 and a floating ring assembly a, wherein the floating ring assembly a is located between the casing 160 and the sealing dynamic ring 170, and the floating ring assembly a and the sealing dynamic ring 170 are clearance-matched and the two are non-centeringly arranged. In some embodiments, the floating ring sealing structure also includes an elastic member a3 and a gasket a2, wherein the elastic member a3 is circumferentially arranged between the casing 160 and the sealing dynamic ring 170, and the elastic member a3 is located on one axial side of the floating ring assembly a; a gasket a2 is provided on one or both axial sides of the elastic member a3, and the gasket a2 is circumferentially arranged between the casing 160 and the sealing dynamic ring 170. In some embodiments, the inner diameter of the elastic member a3 is ≥ the inner diameter of the gasket a2, and / or the inner diameter of the gasket a2 is ≥ the inner diameter of the floating ring assembly a. In some embodiments, refer to Fig. 9 , the elastic member a3 is a wave spring. In some embodiments, the floating ring sealing structure further comprises a retaining ring a1, which is circumferentially arranged between the casing 160 and the sealing dynamic ring 170, and the retaining ring a1 is located on the side of the elastic member a3 axially away from the floating ring assembly a. In some embodiments, the floating ring assembly a comprises a graphite ring a4 and a graphite ring outer ring a5, and the graphite ring outer ring a5 is inlaid on the periphery of the graphite ring a4.

[0045] Second, refer to Figure 3 and Figure 4 The present invention proposes an aircraft engine 100, which includes the floating ring sealing structure of the first aspect. In some embodiments, the aircraft engine 100 also includes a gas turbine rotating part 110, a power turbine rotating part 120 and a compressor rotating part 150 arranged concentrically, the gas turbine rotating part 110 and the compressor rotating part 150 are rotatably arranged through a gas generator rotor transmission shaft 140, the power turbine rotating part 120 is rotatably arranged through a power turbine rotor transmission shaft 130, and the gas generator rotor transmission shaft 140 is nested on the outer side of the turbine rotor transmission shaft; floating ring sealing structures are respectively arranged on both axial sides of the power turbine rotating part 120, and a bearing cavity Q is formed between the two floating ring sealing structures, and at least two bearings 180 are arranged in the bearing cavity Q, and the bearings 180 are respectively sleeved on the power turbine rotor transmission shaft 130 and the gas generator rotor transmission shaft 140. In some embodiments, the floating ring sealing structures on both axial sides are single-stage floating ring sealing structures and / or double-stage floating ring sealing structures.

[0046] In the above embodiment, the aircraft engine 100 of the second aspect includes the floating ring seal structure of the first aspect. Therefore, the aircraft engine 100 of the second aspect has at least all the technical effects of the floating ring seal structure of the first aspect, and its specific technical effects are not repeated here.

[0047] The embodiments of the present application only illustrate the structure of the aircraft engine 100 related to the improvement points of the present application, and do not mean that the aircraft engine 100 of the present application does not have other structures. For example, the aircraft engine 100 also has a combustion chamber, a vortex finder, etc. Other structures will not be described one by one here.

[0048] In a third aspect, the present invention proposes a method for assessing the risk of friction of a floating ring sealing structure, which applies the floating ring sealing structure of the first aspect, and comprises the following steps: analyzing the unbalanced response that may be generated by the rotor of the aircraft engine 100, and further analyzing the maximum response of the sealing dynamic ring 170 on this basis; obtaining the flow field boundary between the floating ring assembly a and the sealing dynamic ring 170 by analysis, establishing a CFD numerical calculation model, and calculating the buoyancy of the floating ring assembly a at different times; calculating the elastic force F3 of the wave spring and the friction force F2 between the floating ring assembly a and the casing 160 and the gasket a2; based on the response analysis of the sealing dynamic ring 170, the buoyancy and friction force F2 analysis of the graphite ring a4, establishing an equivalent calculation model of the dynamic characteristics of the rotor-floating ring sealing structure, analyzing the relative motion relationship between the two, and assessing the risk of friction.

[0049] Specifically, at present, when the aircraft engine 100 is working, in order to prevent the leakage of lubricating oil in the bearing cavity Q and to achieve effective isolation from the external airflow environment, it is necessary to add a sealing structure. Due to the high speed of the aircraft engine 100, in order to prevent excessive wear of the sealing structure, a non-contact sealing structure is usually adopted, for example, Figure 1 The comb teeth sealing structure shown in the figure; wherein, the comb teeth seal is arranged on the casing 160, and there is a certain gap between the comb teeth seal and the sealing dynamic ring 170, so the gas pressure outside the bearing cavity Q is required to be greater than the gas pressure inside the bearing cavity Q. At this time, part of the gas on the outside can flow into the bearing cavity Q, thereby achieving the purpose of preventing the lubricating oil in the bearing cavity Q from leaking out.

[0050] However, affected by the actual working environment of the aircraft engine 100, the temperature of the gas outside the bearing cavity Q is generally higher. If too much gas flows into the bearing cavity Q, it may cause the temperature of the bearing cavity Q to rise and the working environment to deteriorate. On the other hand, excessive gas leakage may also lead to reduced engine efficiency.

[0051] Therefore, on the premise of meeting the lubricating oil sealing requirements, the non-contact sealing device should also minimize the amount of gas leaking into the bearing cavity Q.

[0052] Figure 2 A floating ring seal structure is shown. Compared with a conventional comb seal structure, the graphite ring a4 thereon is not constrained in the radial direction with respect to the casing 160, so that the rigid friction between the rotating part and the casing 160 can be effectively avoided. Therefore, the sealing gap of the floating ring seal structure can be designed to be relatively smaller, thereby further reducing the gas leakage.

[0053] The installation method of the floating ring seal structure in the aircraft engine 100 is as follows: Figure 3 As shown, bearings 180 are respectively arranged at the rear end of the gas turbine rotating part 110 and the front end of the power turbine rotating part 120. When the aircraft engine 100 is working, the bearings 180 are lubricated and cooled by lubricating oil. In order to avoid the adverse effects of the airflow with high external temperature on the bearings 180, the bearings 180 must be effectively isolated from the external airflow as much as possible. At this time, floating ring sealing structures can be respectively arranged on the axial outer sides of the two bearings 180, and a bearing cavity Q is formed between the two floating ring sealing structures and the casing 160, so that the working environment of the bearings 180 can be effectively isolated from the external airflow environment.

[0054] It should be noted that, refer to Figure 6 and Figure 7 The floating ring assembly a and the sealing dynamic ring 170 are non-centeringly arranged. As the buoyancy changes, the eccentricity between the two is in a dynamic change. For details, please refer to the following embodiments:

[0055] Floating ring seal structure Figure 5As shown, the outer ring a5 of the graphite ring and the graphite ring a4 are assembled to form a floating ring assembly a, and the floating ring assembly a is clearance-matched with the sealing dynamic ring 170, and the floating ring assembly a has no radial contact with the casing 160. When the aircraft engine 100 is not working, under the action of gravity F1, the upper part of the floating ring assembly a will fall on the sealing dynamic ring 170 and contact the sealing dynamic ring 170. The floating ring assembly a and the sealing dynamic ring 170 are eccentrically arranged, as shown in FIG. Figure 6 When the aircraft engine 100 is working, external gas will flow into the bearing cavity Q through the gap between the sealing dynamic ring 170 and the floating ring assembly a. Since the floating ring assembly a and the sealing dynamic ring 170 are not concentric, this airflow will produce a fluid dynamic pressure effect, that is, a force that causes the floating ring assembly a to float. When the buoyancy reaches a certain value, the upper part of the floating ring assembly a is out of contact with the sealing dynamic ring 170, and the eccentricity is reduced, as shown in FIG. Figure 7 shown.

[0056] When the aircraft engine 100 is working, the unbalanced mass on the gas generator rotor and the power turbine rotor will arouse an unbalanced response. Since the sealing dynamic ring 170 is a rotating part on the rotor, it will vortex with the rotor. At this time, the relative position of the sealing dynamic ring 170 and the floating ring assembly a will change continuously, causing the flow field parameters of the sealing dynamic ring 170 and the floating ring assembly a to change continuously, thereby causing the buoyancy to change continuously. The change in buoyancy will inevitably cause the floating ring assembly a to follow the movement. Therefore, it is very necessary to analyze the relative movement between the floating ring assembly a and the sealing dynamic ring 170, evaluate the risk of friction, and provide important support for the design of low-leakage and high-reliability floating ring sealing structure.

[0057] At present, in the relevant technology, there is no effective method for assessing the friction risk of the floating ring seal structure in the working state of the aircraft engine 100, which mainly has the following shortcomings:

[0058] 1. The flow field dimensions and gas conditions of the numerical calculation model of the buoyancy on the floating ring seal structure that match the working state of the aircraft engine 100 are not clearly defined;

[0059] 2. When using empirical formulas to calculate the buoyancy on the floating ring, many assumptions are required and the calculation accuracy is not high;

[0060] 3. When using unsteady flow field to analyze the dynamic characteristics of floating ring seal structure, the calculation efficiency and stability are insufficient;

[0061] 4. After obtaining the buoyancy through steady-state flow field calculation, there is a lack of methods for analyzing the dynamic characteristics of the floating ring seal structure;

[0062] 5. There is no quantitative analysis of the impact of the unbalanced response of the gas generator rotor and the power turbine rotor on the risk of friction of the floating ring seal structure;

[0063] 6. No risk assessment of floating ring seal structure friction was conducted based on the engine operating conditions, especially the response analysis of the sealing dynamic ring 170 and the follow-up characteristics analysis of the floating ring seal structure.

[0064] Specifically, refer to Fig.10 When the aircraft engine 100 is working, the imbalance of the rotor causes an unbalanced response. The seal dynamic ring 170, as a rotating part of the rotor, will swirl with the rotor. The swirl of the seal dynamic ring 170 will change the flow field characteristics of the floating ring assembly a, causing the force of the floating ring assembly a to change, causing the floating ring assembly a to move with the seal dynamic ring 170. The analysis of the dynamic characteristics of the floating ring seal structure and the risk assessment of friction mainly include the following tasks:

[0065] Analyze the unbalanced response that may be generated by the rotor of the aircraft engine 100, and further analyze the maximum response of the sealing dynamic ring 170 on this basis;

[0066] The flow field boundary between the floating ring assembly a and the sealing dynamic ring 170 is obtained by analysis, and a CFD numerical calculation model is established to calculate the buoyancy of the floating ring assembly a at different times;

[0067] Calculate the elastic force F3 of the wave spring and the friction force F2 between the floating ring assembly a, the casing 160 and the gasket a2;

[0068] Based on the response analysis of the sealing dynamic ring 170, the buoyancy and friction force F2 on the graphite ring a4, an equivalent calculation model of the dynamic characteristics of the rotor-floating ring sealing structure is established, the relative motion relationship between the two is analyzed, and the risk of friction is evaluated.

[0069] It should be noted that computational fluid dynamics (CFD) is an interdisciplinary subject that combines fluid mechanics, numerical mathematics and computer science. It analyzes and solves fluid flow problems through numerical methods and computer simulation. CFD technology can simulate the physical phenomena of fluids in motion, such as velocity, pressure, temperature and concentration, and predict the interaction between fluids and solid boundaries and the heat and mass transfer process.

[0070] In addition, the response analysis of the sealing dynamic ring 170 includes the response analysis of the sealing dynamic ring 170 installed on the gas generator rotor and the power turbine rotor respectively, providing a basis for the follow-up characteristics analysis of the double-stage floating ring sealing structure of the gas generator rotor and the single-stage floating ring sealing structure of the power turbine rotor.

[0071] Furthermore, changes in the imbalance distribution will cause changes in the rotor imbalance response. In order to effectively evaluate the risk of friction of the floating ring seal structure, it is necessary to evaluate the possible imbalance distribution range under the service conditions of the aircraft engine 100. For nonlinear changes in rotor support stiffness and damping, the relationship between the support load and the change in stiffness and damping can be analyzed in combination with test data, and then the model can be corrected and confirmed. After the model is confirmed, the response characteristics of the sealing dynamic ring 170 within the possible rotor imbalance distribution range under the service conditions of the aircraft engine 100 can be calculated, and the maximum imbalance response of the sealing dynamic ring 170 within the imbalance distribution range can be obtained. The speed range of the imbalance response analysis is the full speed range of the engine. The speed of the maximum response of the sealing dynamic ring 170 is selected as the input condition for the dynamic characteristic analysis of the floating ring seal structure.

[0072] More specifically, the buoyancy analysis of the floating ring assembly a is an important part of the follow-up characteristic analysis and friction assessment. When the aircraft engine 100 is working, the gap value between the floating ring assembly a and the sealing dynamic ring 170 is the basic boundary condition for the buoyancy analysis. The method for determining the working gap of the single-stage floating ring sealing structure and the double-stage floating ring sealing structure can refer to the published patents "A method and system for calculating the working gap of a floating ring sealing structure" (application number: 202210111995.3) and "A method and system, equipment, and medium for calculating the working gap of a double-stage floating ring sealing structure" (application number: 202310382643.6). In order to establish an equivalent calculation model for the dynamic characteristics of the rotor-floating ring sealing structure, it is necessary to calculate the buoyancy between the floating ring assembly a and the sealing dynamic ring 170 in the entire range from the maximum eccentricity (the floating ring assembly a and the sealing dynamic ring 170 are in linear contact) to complete concentricity. More than three interpolation points can be taken. The buoyancy calculation adopts the finite volume method three-dimensional unit for calculation, referring to Fig.11 , the flow field area L needs to include the main sealing surface, and there must be sufficient axial extension at the inlet and outlet of the main sealing surface to ensure that there is no sharp pressure change at the inlet and outlet of the entire flow field calculation, and the end faces of the casing 160 at both ends must meet the axial size requirements; in some embodiments, a wave spring is provided inside the floating ring sealing structure, and gaskets a2 are provided on both sides of the wave spring, and the inner diameter of the gasket a2 is smaller than the inner diameter of the wave spring. Since the inner diameter of the gasket a2 is significantly larger than the inner diameter of the floating ring assembly a, the flow field area where the wave spring area is larger than the inner diameter of the gasket a2 is considered to be a stagnation area and is not considered during modeling to avoid modeling of complex areas including wave springs, which can effectively improve the calculation efficiency but will not substantially affect the calculation accuracy.

[0073] Under the action of the elastic force F3 of the wave spring, the two sides of the floating ring assembly a are respectively fitted with the gasket a2 and the casing 160. When the floating ring assembly a has a radial movement tendency or radial movement, the two fitting surfaces will generate static friction F2 or dynamic friction F2. The magnitude of the friction F2 is related to the elastic force F3 of the wave spring and the surface friction coefficient. After the structure is determined, the elastic force F3 of the wave spring is mainly affected by the working height and temperature. The working height of the wave spring is calculated according to the dimension chain, and the material parameters of the wave spring are changed according to the sealing gas temperature, so as to obtain the elastic force F3 of the wave spring in the working state. The surface friction coefficient is determined by the matching materials, processing accuracy and lubrication conditions, etc., and can be determined by consulting relevant information.

[0074] After completing the above work, an equivalent calculation model of the dynamic characteristics of the rotor-floating ring seal structure can be established. In the equivalent calculation model, the buoyancy of the sealing gas on the floating ring assembly a is equivalent to the wave spring force F3, and the pressure corresponding to different compression amounts of the wave spring is the buoyancy fit obtained by CFD calculation of different eccentricities. In order to avoid large errors in the fitting process, it is necessary to select the maximum eccentricity position, the minimum eccentricity position and at least three eccentricity positions in the middle, and the eccentricity is selected according to an arithmetic progression.

[0075] Reference Figure 8 After establishing the above equivalent model, according to the response of the sealing dynamic ring 170 obtained by the above calculation, a sinusoidal excitation S is applied according to the amplitude and frequency to analyze the relative motion relationship between the sealing dynamic ring 170 and the graphite ring a4. When calculating the relative motion relationship, the compression of the wave spring is calculated according to the eccentricity at each moment, and the elastic force F3 is calculated according to the compression, and then the resultant force on the floating ring assembly a is calculated to obtain the acceleration of the floating ring assembly a, and the acceleration is integrated to obtain the velocity, and then the velocity is integrated to obtain the displacement. During the relative motion process, if the eccentricity at a certain moment exceeds the allowable value, there is a risk of rubbing; if the eccentricity does not exceed the allowable value at any moment, it is considered that the risk of rubbing is small.

[0076] In summary, the floating ring seal structure rubbing risk assessment method provided by the present invention includes:

[0077] 1. Evaluate the possible unbalance distribution range under the service condition of the aircraft engine 100, and on this basis calculate the response of the sealing dynamic ring 170 under the service condition of the aircraft engine 100, and obtain the maximum unbalance response of the sealing dynamic ring 170 within the unbalance distribution range as the input condition for the dynamic characteristic analysis of the floating ring seal structure;

[0078] 2. The nonlinear changes of the stiffness and damping of the rotor support are analyzed in combination with the test data of the full-size rotor, and the relationship between the support load and the stiffness and damping is analyzed to modify and confirm the model;

[0079] 3. Considering the eccentricity between the floating ring assembly a and the sealing dynamic ring 170, the flow field model of the graphite ring a4 and the sealing dynamic ring 170 is established by the finite volume method, and the pressure on the surface of the graphite ring a4 is extracted, which is the buoyancy of the floating ring assembly a;

[0080] 4. The buoyancy calculation is performed using the finite volume method three-dimensional unit. The flow field area needs to include the main sealing surface. There must be sufficient axial extension at the inlet and outlet of the main sealing surface to ensure that there is no sharp pressure change at the inlet and outlet of the entire flow field calculation. The end faces of the casing 160 at both ends must meet the axial size requirements;

[0081] 5. The flow field area where the wave spring area is larger than the inner diameter of the gasket a2 is considered as a stagnation area and is not considered during modeling to avoid modeling complex areas containing wave springs, which can effectively improve the calculation efficiency but will not substantially affect the calculation accuracy;

[0082] 6. Consider the influence of the friction force F2 between the auxiliary sealing surface and the gasket a2 and the graphite ring a4 on the following characteristics of the floating ring assembly a;

[0083] 7. Calculate the working height of the wave spring according to the dimension chain, and change the material parameters of the wave spring according to the sealing gas temperature to obtain the elastic force F3 of the wave spring in the working state;

[0084] 8. The temperature of the floating ring assembly a and the wave spring adopts the sealing gas temperature. The single-stage floating ring sealing structure adopts the high-pressure side gas temperature, the high-pressure side of the double-stage floating ring sealing structure adopts the high-pressure side gas temperature, and the low-pressure side of the double-stage floating ring sealing structure adopts the sealing chamber gas temperature;

[0085] 9. After the buoyancy under different eccentricities is calculated by the finite volume method, the buoyancy of the sealing gas on the floating ring assembly a is equivalent to the elastic force F3 of the wave spring. The pressure corresponding to the different compression amounts of the wave spring is the buoyancy fitting obtained by CFD calculation of different eccentricities.

[0086] 10. According to the response of the sealing dynamic ring 170, a sinusoidal excitation S is applied according to the amplitude and frequency to analyze the relative motion relationship between the sealing dynamic ring 170 and the graphite ring a4. When calculating the relative motion relationship, the compression of the wave spring is calculated according to the eccentricity, and then the elastic force F3 is calculated according to the compression. During the relative motion of the two, if the eccentricity exceeds the allowable value at a certain moment, there is a risk of rubbing; if the eccentricity does not exceed the allowable value at any time, it is considered that the risk of rubbing is small.

[0087] The floating ring seal structure rubbing risk assessment method provided by the present invention has at least the following technical effects:

[0088] 1. The main influencing factors of the floating ring component a and the detailed solution process are given, which provides a basis for quantitative analysis of the following characteristics of the floating ring sealing structure;

[0089] 2. The finite volume method is used to analyze the buoyancy of the three-dimensional grid, which clarifies the necessary flow field calculation area. The calculation results are more accurate than those using empirical formulas, and the calculation efficiency is also taken into account;

[0090] 3. Considering the unbalanced distribution range of the rotor under service conditions and using the response analysis results of the seal dynamic ring 170 confirmed by the model, the friction risk assessment of the floating ring seal structure of the aircraft engine 100 is more suitable for engineering applications;

[0091] 4. An equivalent calculation model for the dynamic characteristics of the rotor-floating ring seal structure was established. Through the analysis of the dynamic characteristics of the floating ring seal structure and the risk of friction, the three-dimensional CFD steady-state flow field calculation results were combined with the classical vibration calculation process. With high calculation accuracy, the shortcomings of low efficiency and easy divergence of unsteady flow field calculation were overcome.

[0092] In particular, the term "and / or" in the present invention should be understood as follows:

[0093] In the first case, the term "and / or" located between a first subject and a second subject includes any one of the following meanings: (1) only the first subject; (2) only the second subject; and (3) the first subject and the second subject.

[0094] In the second case, the term "and / or" between the last two subjects among three or more subjects means including at least any one of the multiple subjects. For example, "the first subject, the second subject and / or the third subject" has the same meaning as "the first subject and / or the second subject and / or the third subject", specifically including the following combinations: (1) only the first subject; (2) only the second subject; (3) only the third subject; (4) the first subject and the second subject but not the third subject; (5) the first subject and the third subject but not the second subject; (6) the second subject and the third subject but not the first subject; and (7) the first subject, the second subject and the third subject.

[0095] In addition, although the above content describes the embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art can also make various modifications and variations without departing from the concept of the present invention, and such modifications and variations all fall within the scope of protection of the present invention.

Claims

1. A floating ring seal structure, characterized in that: The floating ring sealing structure comprises a nested casing (160), a sealing dynamic ring (170) and a floating ring assembly (a); the floating ring assembly (a) is located between the casing (160) and the sealing dynamic ring (170); the floating ring assembly (a) and the sealing dynamic ring (170) are clearance-matched and the two are non-centeringly arranged.

2. The floating ring seal structure according to claim 1, characterized in that: The floating ring sealing structure further comprises an elastic member (a3) ​​and a gasket (a2), wherein the elastic member (a3) ​​is circumferentially arranged between the casing (160) and the sealing dynamic ring (170), and the elastic member (a3) ​​is located on one axial side of the floating ring assembly (a); The gasket (a2) is provided on one or both axial sides of the elastic member (a3), and the gasket (a2) is circumferentially arranged between the casing (160) and the sealing dynamic ring (170).

3. The floating ring seal structure according to claim 2, characterized in that: The inner diameter of the elastic member (a3) ​​is greater than or equal to the inner diameter of the gasket (a2), and / or the inner diameter of the gasket (a2) is greater than or equal to the inner diameter of the floating ring assembly (a).

4. The floating ring seal structure according to claim 2, characterized in that: The elastic member (a3) ​​is a wave spring.

5. The floating ring seal structure according to claim 2, characterized in that: The floating ring sealing structure further comprises a retaining ring (a1), which is circumferentially arranged between the casing (160) and the sealing dynamic ring (170), and the retaining ring (a1) is located on a side of the elastic member (a3) ​​axially away from the floating ring assembly (a).

6. The floating ring seal structure according to any one of claims 1 to 5, characterized in that: The floating ring assembly (a) comprises a graphite ring (a4) and a graphite ring outer ring (a5), and the graphite ring outer ring (a5) is inlaid on the periphery of the graphite ring (a4).

7. An aircraft engine, characterized in that: The aircraft engine (100) comprises the floating ring seal structure according to any one of claims 1 to 6.

8. The aircraft engine according to claim 7, characterized in that: The aircraft engine (100) further comprises a gas turbine rotating component (110), a power turbine rotating component (120) and a compressor rotating component (150) which are arranged concentrically, wherein the gas turbine rotating component (110) and the compressor rotating component (150) are rotatably arranged via a gas generator rotor transmission shaft (140), the power turbine rotating component (120) is rotatably arranged via a power turbine rotor transmission shaft (130), and the gas generator rotor transmission shaft (140) is nested on the outside of the turbine rotor transmission shaft; The floating ring sealing structures are respectively provided on both axial sides of the power turbine rotating component (120), a bearing cavity (Q) is formed between the two floating ring sealing structures, at least two bearings (180) are provided in the bearing cavity (Q), and the bearings (180) are sleeved on the power turbine rotor transmission shaft (130).

9. The aircraft engine according to claim 8, characterized in that: The floating ring sealing structures on both sides of the axial direction are single-stage floating ring sealing structures and / or double-stage floating ring sealing structures.

10. A method for assessing the risk of friction of a floating ring seal structure, characterized in that: The floating ring seal structure according to any one of claims 1 to 6 comprises the following steps: Analyzing the unbalanced response that may be generated by the rotor of the aircraft engine (100), and further analyzing the maximum response of the sealing dynamic ring (170) on this basis; By analyzing and obtaining the flow field boundary between the floating ring assembly (a) and the sealing dynamic ring (170), a CFD numerical calculation model is established to calculate the buoyancy of the floating ring assembly (a) at different times; Calculate the elastic force (F3) of the wave spring and the friction force (F2) between the floating ring assembly (a), the casing (160) and the gasket (a2); Based on the response analysis of the sealing dynamic ring (170), the buoyancy and friction force (F2) on the graphite ring (a4), an equivalent calculation model of the dynamic characteristics of the rotor-floating ring sealing structure is established, the relative motion relationship between the two is analyzed, and the collision risk is evaluated.

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