A multi-layered structure fan case with high inclusion and a design method thereof

Abstract

The application relates to the field of aero-engine design, and discloses a multi-layer structure fan case with high containment and a design method thereof, wherein an anti-collision layer is arranged between an inner heat insulation layer and an outer energy absorption layer of the fan case, the anti-collision layer adopts an arched wall plate and ceramic inserts to jointly resist high-speed impact of a lost blade, the fan case can reduce the structural weight under the condition of meeting the static load, can greatly improve the containment capacity, and can effectively prevent the impact and damage of the lost fan blade. In addition, the application establishes a maximum displacement analysis model of the first arched unit after the first arched unit is subjected to a concentrated load, optimizes the design variables by taking the minimum output value of the maximum displacement analysis model as an optimization target, and determines the optimal size parameters of the first arched unit, so that the design efficiency is improved, the stability and the containment of the fan case under various loads are ensured, the overall performance and the reliability of the fan case are improved, and the demand of various complex working environments is met.

Description

Technical Field

[0001] This invention relates to the field of aero-engine design, and discloses a highly inclusive multi-layered fan casing and its design method. Background Technology

[0002] The fan casing is a crucial component of a turbofan engine, housing high-speed rotating fan blades. These blades are long and heavy; if they break off and fly away, they can cause severe impact and damage to the fan casing. If the fan casing is punctured by a flying blade, the consequences will be extremely serious. Therefore, the fan casing must be able to contain flying blades to ensure flight safety. Currently, containment designs for fan casings mainly fall into two categories: rigid-walled and flexible-walled structures. Rigid-walled fan casings are primarily made of metal, absorbing the impact energy of flying blades through the plastic deformation of the metal. Their main drawback is their relatively large weight. Flexible-walled casings often use lightweight metal as a framework, covered with a fiber-wound layer and resin materials. Some engines also use all-resin composite containment casings. Flexible-walled casings are lightweight and offer good containment, but they are more difficult and costly to manufacture.

[0003] Patent CN1923615A discloses a fiber-reinforced metal / ceramic layered composite enclosure. This enclosure has at least one metal / fiber / ceramic sandwich structure. The metal layer is made of aluminum, titanium, iron, nickel, or their alloys; the fiber layer is made of high-strength quartz fiber, high-strength carbon fiber, or high-modulus carbon fiber; and the ceramic layer is made of alumina, aluminum nitride, silicon carbide, or boron carbide. This invention welds the metal, fiber, and ceramic layers together using casting, powder sintering, and brazing processes. However, during casting and brazing, the three layers need to be heated to 600℃~1650℃, and during powder sintering, they need to be heated to 1200℃~1600℃. Such high heating temperatures approach or even exceed the melting point of the metal layer, which will significantly affect the mechanical properties of the metal and fiber. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-layered fan casing with strong containment and its design method, which can effectively prevent the impact and damage of stray fan blades, ensure the stability and containment of the fan casing when subjected to various loads, thereby improving the overall performance and reliability of the fan casing.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0006] A multi-layered fan casing with a high degree of compatibility, comprising:

[0007] A heat insulation layer is installed on the inside of the fan casing;

[0008] An impact-resistant layer, disposed outside the heat insulation layer, includes an arched wall panel. The arched wall panel comprises multiple circumferentially distributed first arched units, with a second arched unit disposed between two adjacent first arched units. The first arched units and the second arched units have the same cross-sectional shape. The first arched units and the second arched units are smoothly connected alternately to form a corrugated ring structure. Ceramic inserts are respectively inserted into the concave inner side of each first arched unit and each second arched unit.

[0009] An energy-absorbing layer, disposed outside the impact-resistant layer, is a negative Poisson's ratio induced superlattice structure. The equivalent Poisson's ratio of the energy-absorbing layer is -0.4 to -0.8, and the volume fraction is 10% to 30%.

[0010] Furthermore, the surface of the ceramic insert is coated with a 2.0-4.0 mm polyurea coating, the ceramic insert and the concave groove of the arched wall panel are interference fit, and the interference between the ceramic insert and the arched wall panel is 1 / 4 to 1 / 2 of the thickness of the polyurea coating.

[0011] Furthermore, the ceramic material of the ceramic insert includes one or more combinations of silicon carbide, silicon nitride, or aluminum oxide.

[0012] Furthermore, the heat insulation layer is composed of a titanium alloy skin and a supporting structure. The skin thickness is 0.5-0.8 mm. One end of the supporting structure is fixed to the arched wall panel, and the other end of the supporting structure is fixed to the skin.

[0013] Furthermore, the space between the skin and the arched wall panel is filled with aerogel, the thickness of which is 2-5 mm.

[0014] Furthermore, the outer wall of the energy-absorbing layer is also provided with a reinforcing layer, which is woven from at least one fiber material including aramid, carbon fiber, and basalt fiber; after the reinforcing layer is impregnated with epoxy resin or polyimide resin, a polyurea coating is also applied to the outer wall of the reinforcing layer.

[0015] Furthermore, the tensile superlattice structure is also filled with polyurea resin.

[0016] To achieve the above-mentioned technical effects, the present invention also provides a highly inclusive multi-layered fan casing design method, used to obtain the dimensional parameters of the first arched unit of the multi-layered fan casing structure, including:

[0017] Using a thick circular arc structure as the first arch unit, the maximum displacement of the simulated structure under different combinations of circular arc structure dimensional parameters and concentrated loads is obtained through finite element analysis under the constraint that the two ends of the circular arc structure are fixed. The circular arc structure dimensional parameters include the wall thickness, span, and sag of the arc, and the concentrated load is applied at the vertex of the circular arc structure.

[0018] Based on the maximum displacement of the simulated structure under combined conditions, a maximum displacement analysis model based on the dimensional parameters of the circular arc structure and concentrated loads is established.

[0019] Using the wall thickness, span, and rise of the arc as design variables, and under the constraints of the upper limit of the concentrated load and the area limit of the arc structure, the maximum displacement analysis model is used to perform optimization analysis on the design variables. The wall thickness, span, and rise parameter values ​​with the minimum output value of the maximum displacement analysis model are used as the size parameters of the first arch element.

[0020] Furthermore, the maximum displacement analysis model established based on the dimensional parameters of the circular arc structure and the concentrated load is as follows: ,in This is the output value of the maximum displacement analysis model. The elastic modulus of the material of the first arched unit is... Let the moment of inertia be the mid-span section of the first arched element. , The cross-sectional area at the mid-span of the first arched unit is... , The wall thickness is for the arc. Let be the axial length of the arc. The sag of the circular arc structure. For concentrated loads, The span of the circular arc structure.

[0021] Compared with the prior art, the beneficial effects of this invention are:

[0022] 1. The innermost heat insulation layer of the fan casing of this invention can prevent the heat contained within the inner wall of the casing from being transferred to the outside of the casing, thereby reducing the operating temperature of the impact-resistant layer and the energy-absorbing layer. The energy-absorbing layer can be composed of a tensile superlattice structure of titanium alloy with a negative Poisson's ratio, which has good impact resistance. An impact-resistant layer is set between the inner heat insulation layer and the outer energy-absorbing layer of the fan. The impact-resistant layer uses arched wall panels and ceramic inserts to jointly resist the high-speed impact of stray blades. This allows the fan casing to reduce structural weight while meeting the static load requirements, and can significantly improve containment capacity, effectively preventing the impact and damage of stray fan blades.

[0023] 2. This invention establishes a maximum displacement analysis model for the first arched unit under concentrated load, and then uses the arc structure dimension parameters of the first arched unit as design variables. By minimizing the output value of the maximum displacement analysis model as the optimization objective, the optimal dimension parameters of the first arched unit are determined. This not only improves design efficiency but also ensures the stability and containment of the fan casing under various loads, thereby enhancing the overall performance and reliability of the fan casing and meeting the needs of various complex working environments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the multi-layered fan casing structure with strong inclusiveness in the embodiment;

[0025] Figure 2 This is a schematic diagram of the impact-resistant layer in the embodiment;

[0026] Figure 3 This is a schematic diagram of the arched wall panel in the embodiment;

[0027] Figure 4 This is a schematic diagram of the structure of the heat insulation layer in the embodiment;

[0028] Figure 5 This is a schematic diagram of the unit cell structure of the energy-absorbing layer expanded superlattice structure in the embodiment;

[0029] Figure 6 This is a schematic diagram showing the dimensions of the first arched unit in the embodiment;

[0030] Among them, 1. heat insulation layer; 101. skin; 102. support structure; 103. aerogel; 2. impact-resistant layer; 201. arched wall panel; 2011. first arched unit; 2012. second arched unit; 202. ceramic insert; 3. energy-absorbing layer; 301. unit cell; 4. reinforcement layer. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0032] Example 1

[0033] See Figures 1 to 6 A highly inclusive multi-layered fan casing, comprising:

[0034] Heat insulation layer 1 is disposed on the inner side of the fan casing;

[0035] The impact-resistant layer 2, disposed outside the heat insulation layer 1, includes an arched wall panel 201. The arched wall panel 201 includes multiple circumferentially distributed first arched units 2011, and a second arched unit 2012 is disposed between two adjacent first arched units 2011. The first arched units 2011 and the second arched units 2012 have the same cross-sectional shape. The first arched units 2011 and the second arched units 2012 are smoothly connected alternately to form a corrugated ring structure. Ceramic inserts 202 are respectively inserted into the concave inner side of each first arched unit 2011 and each second arched unit 2012.

[0036] The energy-absorbing layer 3, disposed outside the impact-resistant layer 2, is a negative Poisson's ratio expanded superlattice structure. The equivalent Poisson's ratio of the energy-absorbing layer 3 is -0.4 to -0.8, and the volume fraction is 10% to 30%.

[0037] The temperature of the inner wall of the fan housing is relatively high, reaching approximately 200°C, while the temperature of its outer wall is relatively low, close to the temperature in the flight environment. In this embodiment, the innermost heat insulation layer 1 of the fan housing can prevent heat from the inner wall of the housing from being transferred to the outside, thereby reducing the operating temperature of the impact-resistant layer 2 and the energy-absorbing layer 3. The energy-absorbing layer 3 can be composed of a tensile superlattice structure of titanium alloy with a negative Poisson's ratio, and the lattice unit cell 301 is a spline curve structure. This unit cell 301 not only has a low equivalent density, but also, when it is subjected to compression in a certain direction and contracts, the material in the direction perpendicular to it will also contract towards the compressed part, thus giving it good impact resistance. The impact-resistant layer 2 uses an arched wall panel 201 and ceramic inserts 202 to jointly resist the high-speed impact of the lost blade. The arched wall panel 201 can not only quickly transfer and disperse the impact force acting locally to the surrounding structure, but also has good stability and is not easily deformed or unstable when subjected to external impact. The arched ceramic inserts 202 are set on the concave inner side of the arched wall panel 201. The ceramic material can be selected as low-density, high-hardness, high-modulus silicon carbide, silicon nitride, or alumina. The ceramic inserts 202 can not only resist the impact of the lost blade and absorb the kinetic energy of the blade, but also the high hardness of the ceramic inserts 202 and the arched structure can break and cut the flying blade, thereby reducing the further damage of the blade to the housing. In this embodiment, an anti-collision layer 2 is provided between the inner heat insulation layer 1 and the outer energy absorption layer 3 of the fan. The anti-collision layer 2 uses an arched wall panel 201 and a ceramic insert 202 to jointly resist the high-speed impact of the lost blades. This can reduce the structural weight of the fan casing while meeting the requirements of bearing static load, and can greatly improve the containment capacity, effectively preventing the impact and damage of the lost fan blades.

[0038] See Figure 2In this embodiment, the impact-resistant layer 2 uses a titanium alloy arched wall panel 201, a ceramic insert 202, and a polyurea coating to jointly resist the high-speed impact of the stray blade. The polyurea coating is sprayed onto the surface of the ceramic insert 202 with a thickness of 2.0–4.0 mm. The ceramic insert 202 and the concave groove of the arched wall panel 201 are interference-fitted, and the interference between the ceramic insert 202 and the arched wall panel 201 is 1 / 4 to 1 / 2 of the thickness of the polyurea coating. This comprehensively utilizes the impact-resistant properties of metal, ceramic, and resin materials to disperse the impact load. The ceramic material of the ceramic insert 202 is selected as low-density, high-hardness, and high-modulus silicon carbide (SiC). ρ =3.3g / cm 3 E=400~450GPa, Mohs hardness 9.5), silicon nitride ( ρ =3.2g / cm 3 E=300~320GPa, Mohs hardness 8.5) or alumina ( ρ =3.9g / cm 3 (E=380~400GPa, Mohs hardness 9.0). Polyurea coating is a new type of polymer material with high strength and high elasticity. Its molecular chain contains repeating urea and amine functional groups. Polyurea materials have low density ( ρ =0.9~1.1g / cm 3 Polyurea exhibits high strength (tear strength > 40 MPa) and good plasticity (elongation > 700%). When subjected to high-speed impact, the soft segments (polyether chains) of the polyurea molecule can store a large amount of strain energy, while the hard segments (urea bonds) dissipate energy through structural damage and hydrogen bond breaking. This results in a significant strain rate strengthening effect, leading to excellent energy absorption, vibration damping, and impact resistance. Polyurea maintains good flexibility and impact resistance within a temperature range of -50℃ to 150℃, and its temperature resistance is further enhanced after special treatment. In this embodiment, polyurea is sprayed onto the surface of the ceramic insert 202. This serves two purposes: firstly, it provides vibration damping, energy absorption, and impact resistance; secondly, the elastic deformation of the polyurea coating allows for an interference fit between the ceramic insert 202 and the titanium alloy wall panel, preventing displacement and movement of the ceramic insert 202 within the gaps in the wall panel.

[0039] In this embodiment, the structure of the heat insulation layer 1 is as follows: Figure 4As shown, the heat insulation layer 1 is composed of a titanium alloy skin 101 and a rod-shaped support structure 102. The skin 101 has a thickness of 0.5-0.8 mm and is located in the innermost layer of the housing. A 1.2 mm thick Al / h-BN abrasive sealing coating is sprayed onto the skin 101 at the position corresponding to the fan rotor blades. Its main function is to form the internal flow channel of the housing. The rod-shaped support structure 102 has a diameter of 1 mm and is connected to the skin 101 and the impact-resistant layer 2, serving to support the skin 101 and withstand the internal pressure. The gap between the skin 101 and the rod-shaped support structure 102 is filled with aerogel 103 to prevent heat from spreading from the inside to the outside in the form of convection or radiation. The aerogel 103 has a thickness of 2-5 mm.

[0040] Energy Absorbing Layer 3 Figure 5 As shown, the structure is mainly composed of a titanium alloy lattice with a negative Poisson's ratio, and the lattice unit cell 301 has a spline curve structure. The height of unit cell 301 along the wall thickness direction of the enclosing casing is 2mm~5mm, the wall thickness of unit cell 301 is 0.6mm~1.0mm, the equivalent Poisson's ratio of unit cell 301 is -0.4~-0.8, and the volume fraction of unit cell 301 is 10%~30%; the tensile lattice material with a negative Poisson's ratio is titanium alloy. This unit cell 301 not only has a low equivalent density, but also, when it is subjected to compression in a certain direction and shrinks, the material in the direction perpendicular to it will also shrink towards the compressed part, thus giving it good impact resistance. Filling the pores of the tensile lattice with polyurea material can further improve the energy absorption effect of this structure.

[0041] In this embodiment, the outer wall of the energy-absorbing layer 3 is further provided with a reinforcing layer 4, which is woven from at least one fiber material including aramid, carbon fiber, and basalt fiber. After impregnation with epoxy resin or polyimide resin, the outer wall of the reinforcing layer 4 is coated with a polyurea coating. The reinforcing layer 4 uses high-strength aramid fiber, carbon fiber, or basalt fiber as the reinforcing body, which is wound and woven in a warp and weft pattern on the outermost layer of the housing. These fibers have high tensile strength, which can not only improve the housing's containment capacity but also enhance its ability to withstand static loads. To improve the reinforcing effect of the fibers, epoxy resin or polyimide resin is impregnated between the fiber filaments, protecting the fibers while improving the plasticity and toughness of the housing layer. Finally, a polyurea coating can be sprayed onto the outer surface of the reinforcing layer 4 to improve the static load-bearing capacity.

[0042] In this embodiment, the manufacturing sequence of the fan casing is as follows: first, the additive manufacturing and heat treatment of the titanium alloy part are completed; then, the filling preparation of aerogel 103 in the heat insulation layer 1 is completed; then, the preparation of the reinforcing layer 4 is completed; then, ceramic inserts 202 coated with polyurea are inserted into the gaps of the arched wall panel 201 of the impact-resistant layer 2; finally, polyurea is poured into the gaps of the energy-absorbing layer 3 and cured to form a multi-layered fan casing structure with strong containment.

[0043] Based on the same inventive concept, this embodiment also provides a highly inclusive multi-layered fan casing design method for obtaining the dimensional parameters of the first arched unit 2011 of the multi-layered fan casing structure, including:

[0044] Step 1: Using a thick circular arc structure as the simulated structure of the first arch unit 2011, under the constraint that the two ends of the circular arc structure are fixed, the maximum displacement of the simulated structure under different combinations of circular arc structure dimensional parameters and concentrated loads is obtained through finite element analysis; the circular arc structure dimensional parameters include the wall thickness, span, and sag of the arc, and the concentrated load is applied at the vertex position of the circular arc structure.

[0045] Step 2: Based on the maximum displacement of the simulated structure under combined conditions, establish a maximum displacement analysis model based on the dimensional parameters of the circular arc structure and the concentrated load;

[0046] In this embodiment, the maximum displacement analysis model established based on the dimensional parameters of the circular arc structure and the concentrated load is as follows: ,in This is the output value of the maximum displacement analysis model. The elastic modulus of the material of the first arched unit is... Let the moment of inertia be the mid-span section of the first arched element. , The cross-sectional area at the mid-span of the first arched unit is... , The wall thickness is for the arc. Let be the axial length of the arc. The sag of the circular arc structure. For concentrated loads, The span of the circular arc structure.

[0047] Using the wall thickness, span, and rise of the arc as design variables, and under the constraints of the upper limit of the concentrated load and the area limit of the arc structure, the maximum displacement analysis model is used to perform optimization analysis on the design variables. The wall thickness, span, and rise parameter values ​​with the minimum output value of the maximum displacement analysis model are used as the size parameters of the first arch element 2011.

[0048] This embodiment establishes a maximum displacement analysis model of the first arched unit 2011 under concentrated load, and then uses the arc structure size parameters of the first arched unit 2011 as design variables. The optimization objective is to minimize the output value of the maximum displacement analysis model to optimize the design variables, thereby determining the optimal size parameters of the first arched unit 2011. This not only improves design efficiency, but also ensures the stability and containment of the fan casing under various loads, thereby improving the overall performance and reliability of the fan casing and meeting the needs of various complex working environments.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-layered fan casing with strong compatibility, characterized in that, include: A heat insulation layer is installed on the inside of the fan casing; An impact-resistant layer, disposed outside the heat insulation layer, includes an arched wall panel. The arched wall panel comprises multiple circumferentially distributed first arched units, with a second arched unit disposed between two adjacent first arched units. The first arched units and the second arched units have the same cross-sectional shape. The first arched units and the second arched units are smoothly connected alternately to form a corrugated ring structure. Ceramic inserts are respectively inserted into the concave inner side of each first arched unit and each second arched unit. An energy-absorbing layer, disposed outside the impact-resistant layer, is a negative Poisson's ratio tensile superlattice structure. The equivalent Poisson's ratio of the energy-absorbing layer is -0.4 to -0.8, and the volume fraction is 10% to 30%. A reinforcing layer is also disposed on the outer wall of the energy-absorbing layer. The reinforcing layer is woven from at least one fiber material including aramid, carbon fiber, and basalt fiber. After the reinforcing layer is impregnated with epoxy resin or polyimide resin, a polyurea coating is also coated on the outer wall of the reinforcing layer. The heat insulation layer consists of a titanium alloy skin and a supporting structure. The skin thickness is 0.5-0.8 mm. One end of the supporting structure is fixed to the arched wall panel, and the other end of the supporting structure is fixed to the skin.

2. The multi-layer fan casing according to claim 1, characterized in that, The ceramic insert is coated with a 2.0-4.0 mm polyurea coating. The ceramic insert and the concave groove of the arched wall panel are interference fit, and the interference between the ceramic insert and the arched wall panel is 1 / 4 to 1 / 2 of the thickness of the polyurea coating.

3. The multi-layer fan casing according to claim 2, characterized in that, The ceramic material of the ceramic insert includes one or more combinations of silicon carbide, silicon nitride, or aluminum oxide.

4. The multi-layer fan casing according to claim 1, characterized in that, The space between the skin and the arched wall panel is filled with aerogel, the thickness of which is 2-5 mm.

5. The multi-layer fan casing according to claim 1, characterized in that, The tensile superlattice structure is also filled with polyurea resin.

6. A highly inclusive multi-layer fan casing design method, used to obtain the dimensional parameters of the first arched unit of the multi-layer fan casing structure according to any one of claims 1-5, characterized in that, include: Using a thick circular arc structure as the first arch unit, the maximum displacement of the simulated structure under different combinations of circular arc structure size parameters and concentrated loads is obtained through finite element analysis under the constraint that the two ends of the circular arc structure are fixed. The dimensional parameters of the arc structure include the wall thickness, span, and sag of the arc, and the concentrated load is applied at the vertex of the arc structure. Based on the maximum displacement of the simulated structure under combined conditions, a maximum displacement analysis model based on the dimensional parameters of the circular arc structure and concentrated loads is established. Using the wall thickness, span, and rise of the arc as design variables, and under the constraints of the upper limit of the concentrated load and the area limit of the arc structure, the maximum displacement analysis model is used to perform optimization analysis on the design variables. The wall thickness, span, and rise parameter values ​​with the minimum output value of the maximum displacement analysis model are used as the size parameters of the first arch element.

7. The multi-layer fan casing design method according to claim 6, characterized in that, The established maximum displacement analysis model based on the dimensional parameters of the circular arc structure and concentrated loads is as follows: ,in This is the output value of the maximum displacement analysis model. The elastic modulus of the material of the first arched unit is... Let the moment of inertia be the mid-span section of the first arched element. , The cross-sectional area at the mid-span of the first arched unit is... , The wall thickness is for the arc. Let be the axial length of the arc. The sag of the circular arc structure. For concentrated loads, The span of the circular arc structure.

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