Multilayer solid structure contained by centripetal impeller

Abstract

The invention relates to the technical field of turbine protection, and provides a multilayer solid structure containing a centripetal impeller, the multilayer solid structure comprises a first protection layer, a guider and a second protection layer, a first protection layer reserved gap is arranged on an outer ring of the guider, a second protection layer reserved gap is arranged on an inner ring of the guider, and the first protection layer covers the guider and the second protection layer. The guider can preliminarily block fragments, the second protection layer absorbs a large amount of fragment kinetic energy through material deformation and structural damage, the first protection layer provides final protection and structural support through buffering, and the capacity of containing high-energy fragments is remarkably improved. The synergistic effect of a multi-layer structure is achieved, and fragments generated by different failure modes of the centripetal impeller can be effectively handled.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of turbine protection, and particularly relates to a multi-layer solid structure for containing a centripetal impeller. BACKGROUND

[0002] An aviation auxiliary power unit (APU) is a key auxiliary equipment of an airplane, and a centripetal turbine is widely used due to its compact structure and high power density. The centripetal impeller, as a core rotor component of the turbine, needs to work continuously under extreme working conditions of high temperature, high pressure and high speed rotation. Once failure occurs, high-speed flying fragments will carry huge kinetic energy. These high-energy fragments may penetrate the casing and then hit key components such as the airplane cabin, fuel tank and control circuit, causing serious safety accidents such as cabin pressure loss, fuel leakage and fire, flight control system failure, and posing a major threat to aviation safety. At present, the traditional APU structure design has significant limitations in fragment containment. The existing design can only cope with low-energy failure scenarios such as local blade drop or single blade fracture, and cannot effectively contain high-energy fragments generated by disc rupture. When the disc ruptures, due to its larger mass and higher rotational speed, the kinetic energy released by the fragments far exceeds the bearing limit of the traditional casing, resulting in the complete failure of the existing protection system under extreme failure conditions. It is difficult to meet the stringent requirements of aviation safety standards for the overall safety of the APU system. Therefore, it is urgent to develop a new type of high-efficiency fragment containment technology to fill this gap. SUMMARY

[0003] To solve the above problems, the application provides a multi-layer solid structure for containing a centripetal impeller, which comprises a first protective layer, a guider and a second protective layer. The first protective layer is arranged on the outer ring of the guider with a reserved gap, the second protective layer is arranged on the inner ring of the guider with a reserved gap, and the first protective layer covers the guider and the second protective layer.

[0004] Optionally, the first protective layer is located on the inlet end of the guider, and the second protective layer is located on the outlet end of the guider.

[0005] Optionally, the thickness of the first protective layer is H1-H2 millimeters.

[0006] Optionally, the thickness of the second protective layer is H3-H4 millimeters.

[0007] Optionally, the second protective layer has an arc-shaped structure.

[0008] Optionally, the application further comprises a centripetal wheel, which is located at the outlet of the guider, and the guider is adjacent to the second protective layer.

[0009] Optionally, the axial length of the second protective layer is greater than or equal to the axial length of the centripetal wheel.

[0010] Optionally, the gap a between the first protective layer and the guide is greater than the difference between the deformation b of the guide and the deformation of the second protective layer.

[0011] Optionally, a plurality of fixing structures are further included, and the plurality of fixing structures are fixedly connected through the first protective layer and the guide.

[0012] Optionally, one end of the second protective layer is provided with an internal thread, an outer ring of the guide is provided with an external thread, and the internal thread is matched with the external thread.

[0013] The multi-layer solid structure for containing the centripetal impeller provided by the application has the following advantages compared with the prior art: The generated fragments first pass through the outer ring or the inner ring of the guide for first buffering, pass through the second protective layer for second buffering if passing through the inner ring of the guide, pass through the first protective layer for third buffering if still unable to block the fragments after the second buffering, and finally block the fragments. The fragments can also be blocked from continuing to move if passing through the outer ring of the guide for second buffering. The multi-layer structure realizes the synergistic effect, can effectively cope with the fragments generated by different failure modes of the centripetal impeller. The guide can preliminarily block the fragments, the second protective layer absorbs a large amount of kinetic energy of the fragments through material deformation and structural damage, and the first protective layer provides the final protection and structural support, thereby significantly improving the containing capacity for high-energy fragments.

[0014] Other features and advantages of the present application will be described in the following description, and some will become apparent from the description, or will be learned from the practice of the application. The purposes and other advantages of the present application can be achieved and obtained by the structures indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0016] Figure 1 Fig. 1 shows a schematic diagram of a multi-layer solid structure for containing a centripetal impeller in an embodiment of the present application; Figure 2 Fig. 1 shows a schematic diagram of a multi-layer solid structure for containing a centripetal impeller in an embodiment of the present application;

[0017] In the figure, 1 is a first protective layer, 2 is a guide, 3 is a second protective layer, 4 is a centripetal wheel, and 5 is a fixing structure. DETAILED DESCRIPTION

[0018] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely explain the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0019] As shown in Figure 1 The present application provides a multi-layer solid structure for containing a radial impeller, which comprises a first protective layer 1, a guider 2 and a second protective layer 3. The first protective layer 1 is arranged on an outer ring of the guider 2 with a gap, the second protective layer 3 is arranged on an inner ring of the guider 2 with a gap, and the first protective layer 1 covers the guider 2 and the second protective layer 3. Thus, the synergistic effect of the multi-layer structure can effectively deal with the fragments generated by different failure modes of the radial impeller. The guider 2 can preliminarily block the fragments, the second protective layer 3 can absorb a large amount of kinetic energy of the fragments through material deformation and structural damage, and the first protective layer can provide the final protection and structural support, thereby significantly improving the containing capacity for high-energy fragments. The first protective layer 1, the guider 2 and the second protective layer 3 are used to contain high-energy fragments generated by local blockage, blade fracture and disc rupture of the radial impeller. It should be noted that the materials of the first protective layer 1, the guider 2 and the second protective layer 3 can be high-temperature alloy, titanium alloy, aluminum alloy, titanium-aluminum alloy, composite material, etc. Optionally, the first protective layer 1, the guider 2 and the second protective layer 3 in the embodiment are all made of high-temperature alloy.

[0020] In an embodiment, the first protective layer 1 is located on the inlet end of the guider 2, and the second protective layer 3 is located on the outlet end of the guider 2. Through the first protective layer 1 on the inlet end of the guider 2, the fragments can be prevented from breaking through the inlet end of the guider 2, and through the second protective layer 3 on the outlet end of the guider 2, the fragments can be prevented from breaking through the outlet end of the guider 2, thereby improving the protection effect.

[0021] In an embodiment, the thickness of the first protective layer 1 is H1-H2 millimeters. The thickness should be designed according to the energy of the fragments generated when the radial impeller is broken. The initial diameter and thickness of the first protective layer 1 and the second protective layer 3 are determined by using the containment coefficient method, and the outer casing and the guider 2 both contribute to the containment. The parts with smaller contribution can be appropriately simplified in the containment analysis. Optionally, the thickness of the first protective layer 1 is specifically between 10-15 (H1-H2) millimeters, and can be 10, 11, 12, 13, 14 and 15 millimeters.

[0022] In an embodiment, the second protective layer 3 has a thickness of H3-H4 millimeters. The thickness should be designed according to the fragment energy generated when the centrifugal impeller breaks, and the containment coefficient method is used to determine the initial diameter and thickness of the first protective layer 1 and the second protective layer 3. The outer casing and the guide 2 both contribute to containment, and the parts that contribute less can be appropriately simplified in the containment analysis. Alternatively, the thickness of the second protective layer 3 is specifically between 2-5 (H3-H4) millimeters, which can be 2, 3, 4, and 5 millimeters. It should be noted that according to the energy distribution of the breakage, the thickness ratio of the two protective layers is generally 4:1-5:1.

[0023] In an embodiment, the second protective layer 3 has an arc-shaped structure. Through the arc-shaped structure, the inner ring of the guide 2 can be covered, that is, part of the structure of the centrifugal impeller can be covered, so as to effectively block and buffer the fragments coming out of the outer ring of the guide 2.

[0024] In an embodiment, it further includes a centrifugal wheel 4 located at the outlet of the guide 2, and the guide 2 is adjacent to the second protective layer 3. The function of the centrifugal impeller is to convert heat energy into mechanical energy to do work; the function of the guide 2 is to adjust the direction of the gas flow, so that the gas can enter the centrifugal impeller more efficiently, and it also has the effect of reducing the impact force of the local block of the centrifugal impeller. Through the second protective layer 3, part of the structure of the centrifugal impeller can be covered, so as to effectively block and buffer the fragments coming out of the outer ring of the guide 2.

[0025] In one embodiment, the axial length of the second protective layer 3 is greater than or equal to the axial length of the centripetal impeller 4. Specifically, the axial length of the second protective layer 3 should cover the centripetal impeller blades as much as possible, generally 3 / 5-4 / 5 of the axial length of the centripetal impeller blades, and the inner ring rear end surface of the second protective layer 3 should be aligned with the blade exhaust edge. The axial span of the first protective layer 1 should include the axial range corresponding to the centripetal impeller. The guide vane 2 and the annular structure both have a certain effect on containment, and the blade thickness and annular structure thickness are designed on the basis of meeting the performance requirements. After determining the basic parameters of the containment structure, detailed design is carried out according to the structure space size and installation interface, and finally the containment simulation analysis method is used to analyze the debris path and containment capacity. Specifically, in the first step, the debris energy generated when the centripetal impeller breaks is calculated according to the material of the centripetal impeller, the working speed, and the breaking form. In the second step, the contribution coefficients of the first and second protective layers 3 are reasonably allocated according to the material and thickness of each layer of parts on the debris flight path. In the third step, the initial parameters (material, diameter, thickness, and axial length) of the first and second protective layers 3 are determined according to the contribution coefficients. In the fourth step, the first and second protective layers 3 are designed in detail according to the structure space size and installation interface. In the fifth step, all the parts on the containment path are modeled. In the sixth step, the material parameters, working speed, temperature, mesh division, boundary conditions, and friction coefficient of the parts are set, and the simulation animation is output to complete the containment simulation analysis. In the seventh step, it is determined whether the requirements are met. If not, the third step needs to be re-executed until the requirements are met and output. Through this step, the required first protective layer 1 and second protective layer 3 are finally obtained.

[0026] In one embodiment, the gap a between the first protective layer 1 and the guide vane 2 is greater than the difference between the deformation b of the guide vane 2 and the deformation c of the second protective layer 3. It should be noted that the guide vane 2 contacts the gas and thus has high temperature and large deformation, and the second protective layer 3 has low temperature and small deformation in order to make the material more ductile and have stronger containment capacity. Therefore, the connection between the guide vane 2 and the first protective layer 1 should be reliable and as little affected as possible by the deformation of each other. Therefore, a sufficient gap a should be left between the guide vane 2 and the first protective layer 1, and the gap a should be greater than the difference between the deformation b of the guide vane 2 and the deformation c of the second protective layer 3, i.e. a > b-c. Thus, the temperature deformation interference is avoided.

[0027] As Figure 2As shown, in one embodiment, a plurality of fixing structures 5 are fixedly connected to the first protective layer 1 and the guide 2. Optionally, the fixing structures 5 are pins, and the pins are connected by a plurality of pins, and the number of pins is generally 4-8. A part of the pins is located in the guide 2, and a part of the pins is located in the first protective layer 1. The pins can slide in the holes in the first protective layer 1 and the holes in the guide 2. The hole in the guide 2 is a stepped hole, so that the pins will not slide into the guide 2. The hole in the first protective layer 1 is a through hole, and after the pins are installed, the hole is punched and riveted, so that the pins will not slide out of the first protective layer 1. The pins can be made of high-strength alloy steel, and the diameter can be designed according to the needs, and the nuts and washers matched with the pins are also provided. The washer is an elastic washer, and is made of spring steel. The pins are made of high-strength alloy steel, and are matched with the elastic washer, and after installation, the hole is punched and riveted to prevent falling off.

[0028] In one embodiment, one end of the second protective layer 3 is provided with an internal thread, the outer ring of the guide 2 is provided with an external thread, and the internal thread is matched with the external thread. It should be noted that when installing, the second protective layer 3 is screwed into the guide 2, and the thin-walled position at the tail of the second protective layer 3 is punched and riveted. The second protective layer 3 must be reliably fixed to prevent it from deviating from the original position and causing containment failure. The second protective layer 3 must form a long cavity with the guide 2 to prevent the guide 2 with high temperature from radiating heat to the second protective layer 3, causing the temperature of the first protective layer 1 to be too high and the containment capacity to decrease.

[0029] In summary, in the above failure modes, the largest energy is generated when one-third of the blades of the disk are broken, and it is also the most difficult to contain. When one-third of the disk is broken, the broken disk rotates and flies outwards. The outer ring of the disk is worn by friction every time it is hit. The tip first contacts the annular structure on the inner ring of the guide 2 and the blades of the guide 2. The annular structure of the guide 2 is broken, and then it hits the second protective layer 3. After the rotating disk hits the second protective layer 3 which has good ductility, the second protective layer 3 absorbs part of the energy of the fragments through large deformation, changes the running direction of the disk, and reduces the impact energy of the fragments next time. The fragments that change direction continue to hit the blades of the guide 2, and finally hit the first protective layer 1. The first protective layer 1 absorbs the remaining energy of the fragments through large deformation. The small fragments generated after the impact of the guide 2 and other parts have small energy and can be contained by other casing structures and protective layers.

[0030] In addition, when the centripetal impeller blade is broken or the blade is partially broken, the annular structure and the blades on the second protective layer 3 and the guide 2 can absorb most of the energy of the fragments, and the first protective layer 1 is only slightly damaged or not damaged. The damage range can be controlled within the turbine, and the secondary damage range is reduced.

[0031] The application realizes efficient protection of the full failure mode of the centripetal impeller through the synergistic design and optimized connection mode of the multi-layer solid structure, and especially solves the containment problem of the high-energy fragments of the broken disk. The structural design takes into account the energy absorption efficiency, temperature adaptability and lightweight requirements, and provides reliable protection for the safe operation of the APU centripetal turbine, and has important engineering application value.

[0032] Although the application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A multi-layered solid structure enclosed by a centripetal impeller, characterized in that, include: The first protective layer (1), the guide (2), and the second protective layer (3) are provided. The first protective layer (1) has a reserved gap on the outer ring of the guide (2), and the second protective layer (3) has a reserved gap on the inner ring of the guide (2). The first protective layer (1) covers the guide (2) and the second protective layer (3).

2. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, The first protective layer (1) is located on the inlet end of the guide (2), and the second protective layer (3) is located on the outlet end of the guide (2).

3. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, The thickness of the first protective layer (1) is H1-H2 mm.

4. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, The thickness of the second protective layer (3) is H3-H4 mm.

5. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, The second protective layer (3) has an arc-shaped structure.

6. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, It also includes a centripetal wheel (4), which is located at the outlet of the guide (2) and the guide (2) is adjacent to the second protective layer (3).

7. The multi-layer solid structure enclosed by the centripetal impeller according to claim 6, characterized in that, The axial length of the second protective layer (3) is greater than or equal to the axial length of the radial wheel (4).

8. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, The gap a between the first protective layer (1) and the guide (2) is greater than the difference between the deformation b of the guide (2) and the deformation of the second protective layer (3).

9. The multi-layer solid structure enclosed by the centripetal impeller according to claim 1, characterized in that, It also includes multiple fixing structures (5), which pass through the first protective layer (1) and are fixedly connected to the guide (2).

10. The multi-layer solid structure encompassed by the centripetal impeller according to claim 1, characterized in that, One end of the second protective layer (3) is provided with an internal thread, and the outer ring of the guide (2) is provided with an external thread, and the internal thread and the external thread are engaged.

Images