A CMC blade tenon based on metal edge wrapping

Abstract

The present invention relates to the technical field of turbine blades, and discloses a CMC blade tenon based on metal edge wrapping, which includes a metal layer that can be sleeved outside the CMC blade tenon. The metal layer includes a first contact layer that fits the working surface of the CMC blade tenon and a second contact layer that fits the non-working surface of the CMC blade tenon. A first pin hole is formed on the non-working surface, and a second pin hole that cooperates with the first pin hole is formed on the second contact layer. By wrapping the CMC blade tenon with a metal layer and inserting pins into the first pin hole and the second pin hole on the non-working surface of the CMC blade tenon to realize the connection and fixation between the metal layer and the CMC blade tenon, the present invention can effectively reduce the micro-slip between the CMC blade tenon and the metal layer, thereby solving the friction and wear problem at the contact interface between the CMC blade tenon and the metal layer; it can also improve the strength reserve of the CMC blade, enhance the service life of the turbine blade and the service reliability of the engine at high speeds.

Description

Technical Field

[0001] The present invention relates to the technical field of turbine blades, and discloses a CMC blade tenon based on metal edging. Background Art

[0002] With the development of aero-engines towards high thrust-to-weight ratio and lightweight, the application proportion of lightweight and high-temperature-resistant ceramic matrix composites (CMC) in the aviation field has been increasing in recent years, and it has developed from the application in non-load-bearing components and secondary load-bearing structures to more and more applications in main load-bearing components. The maximum service temperature of CMC ceramic matrix composites can reach 1600 °C, and they are applied to components such as combustion chambers, outer rings, turbine rotor blades, and turbine guide vanes, greatly reducing fuel consumption and increasing the operating mileage. The application of the turbine rotor blades of the GE9X engine is the first application of composites in aviation rotating components and has become the application direction of advanced aero-engine composites; 9500083B2 uses a metal layer to reduce the friction coefficient between CMC components and metal components, mainly to reduce the friction and wear between the tenons of CMC rotor blades and the dovetail grooves of metal material discs. However, this patent does not consider whether the bearing capacity of the CMC ceramic matrix composite applied to the tenons of high-performance engine turbine rotor blades meets the service requirements, and the clamp for limiting the blade and the metal layer will bring great difficulties to the engine assembly design. The working environment of CMC turbine blades is harsh. When working under large loads, they also suffer from gas corrosion, friction and wear between the tenon teeth of the blades and the discs made of superalloy materials, fretting fatigue and other damages, greatly reducing the service life of CMC blades.

[0003] At present, the temperature of the tenons of advanced engine turbine rotor blades in the world is higher than 1000K, and the tensile stress borne by the working surface of the tenons exceeds 260 MPa. The tensile strength and shear strength of the CMC composite tenon teeth cannot meet the requirements of engine strength and service life. Therefore, when designing the structural strength of CMC ceramic matrix composite turbine blades, in addition to considering the problem of friction and wear, it is also necessary to consider its bearing capacity and the assembly problem with engine rotating components. Summary of the Invention

[0004] The purpose of the present invention is to provide a CMC blade tenon based on metal edging, which can effectively reduce the micro-slip between the CMC blade tenon and the metal layer, thereby solving the problem of friction and wear at the contact interface between the CMC blade tenon and the metal layer; it can also improve the strength reserve of CMC blades, extend the service life of turbine blades, and enhance the service reliability of the engine at high speeds.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0006] A CMC blade tenon based on metal edging, comprising a metal layer sleeved outside the CMC blade tenon. The metal layer includes a first contact layer attached to the working surface of the CMC blade tenon and a second contact layer attached to the non-working surface of the CMC blade tenon. A first pin hole is formed on the non-working surface, and a second pin hole matching the first pin hole is formed on the second contact layer.

[0007] Further, the CMC blade tenon is fixedly connected by metal pins inserted into the first pin hole and the second pin hole, and the metal pins are inserted into the first pin hole and the second pin hole in an interference fit manner.

[0008] Further, the number of the first pin holes on the non-working surface of the CMC blade tenon is determined as follows:

[0009] Calculate the loads on the working surface and the non-working surface of the CMC blade according to the service conditions of the CMC blade, and calculate the number of the first pin holes on the non-working surface through the formula ; where F is the centrifugal force of the blade under the engine working condition, θ is the angle between the non-working surface of the tenon and the centrifugal force of the blade, and σ0 is the yield strength of the metal pin material.

[0010] Further, the contact area between the working surface and the first contact layer is determined by the formula ; where F is the centrifugal force of the blade under the engine working condition, α is the angle between the working surface of the tenon and the centrifugal force of the blade, and σ0 is the yield strength of the metal pin material.

[0011] Further, a vapor deposition layer is provided between the outer wall of the CMC blade tenon and the inner wall of the metal layer.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] By covering the CMC blade tenon with a metal layer and connecting and fixing the metal layer and the CMC blade tenon by inserting pins into the first pin hole and the second pin hole on the non-working surface of the CMC blade tenon, the present invention can effectively reduce the micro-slip between the CMC blade tenon and the metal layer, thereby solving the friction and wear problem at the contact interface between the CMC blade tenon and the metal layer; it can also improve the strength reserve of the CMC blade, extend the service life of the turbine blade and improve the service reliability of the engine at high speeds. Description of the Drawings

[0014] Figure 1 Schematic diagram of the split structure of the CMC blade tenon based on metal edging in the embodiment;

[0015] Figure 2Schematic diagram of the connection relationship between the metal layer and the CMC blade tenon in the embodiment;

[0016] Figure 3 Schematic diagram of the installation of the CMC blade tenon with a metal edge and the disk tenon groove in the embodiment;

[0017] Among them, 1. CMC blade tenon; 2. Metal layer; 3. Working surface; 4. First contact layer; 5. Non-working surface; 6. Second contact layer; 7. First pin hole; 8. Second pin hole; 9. Metal pin; 10. Tenon groove. Detailed implementation mode

[0018] The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings. However, this should not be understood as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0019] Embodiment

[0020] See Figures 1-3 , a CMC blade tenon based on a metal edge, including a metal layer 2 sleeved outside the CMC blade tenon 1. The metal layer 2 includes a first contact layer 4 attached to the working surface 3 of the CMC blade tenon 1 and a second contact layer 6 attached to the non-working surface 5 of the CMC blade tenon 1. A first pin hole 7 is provided on the non-working surface 5, and a second pin hole 8 matching the first pin hole 7 is provided on the second contact layer 6.

[0021] In this embodiment, after assembling the CMC blade tenon 1 with a metal layer 2 edge on the disk, the outer surface of the working surface 3 of the metal layer 2 is assembled on the working surface 3 of the disk tenon groove 10, and the outer surface of the non-working surface 5 of the metal layer 2 is assembled on the working surface 3 of the disk tenon groove 10. By wrapping the metal layer 2 outside the blade tenon made of CMC ceramic matrix composite material and inserting pins into the first pin hole 7 and the second pin hole 8 on the non-working surface 5 of the CMC blade tenon 1 to connect and fix the metal layer 2 and the CMC blade tenon 1 into an integral tenon structure, the micro-slip between the CMC blade tenon 1 and the metal layer 2 can be effectively reduced, thereby solving the friction and wear problem at the contact interface between the CMC blade tenon 1 and the metal layer 2; at the same time, it can also improve the strength reserve of the CMC blade, extend the service life of the turbine blade, and improve the service reliability of the engine at high speeds.

[0022] In this embodiment, the CMC blade tenon 1 is fixedly connected by a metal pin 9 inserted into the first pin hole 7 and the second pin hole 8. The metal pin 9 is inserted into the first pin hole 7 and the second pin hole 8 in an interference fit manner. According to the working conditions of the CMC turbine blade, the material of the metal layer 2 can be selected as the Ni-based precipitation-hardened wrought superalloy GH4738. Considering the deformation coordination, the connecting pin is selected as the GH4738 material, and the simulated structural material of the disk is the GH4175 material. The working temperature of the GH4738 wrought superalloy is 1088K, and it has high yield strength and fatigue resistance at the working temperature, and good oxidation and corrosion resistance in the gas turbine atmosphere. After the CMC blade adopts the GH4738 material layer, the strength reserve of the working surface 3 of the tenon teeth is increased by more than 50%, meeting the engine strength design requirements. In this embodiment, the thickness of the metal layer 2 made of GH4738 material is >1mm to meet the stiffness requirements; the connection position of the metal pin 9 is designed on the non-working surface 5 of the CMC blade tenon 1. During operation, it is only affected by thermal stress, which greatly reduces the requirement for the connection strength of the metal pin 9, and at the same time reduces the stress concentration degree of the first pin hole 7 on the non-working surface 5 of the CMC blade tenon 1 and the first pin hole 7 on the corresponding metal layer 2. In addition, in this embodiment, considering the relatively low cost, the material of the metal layer 2 is selected as the GH4738 material with a relatively high working temperature. If cost is not considered, the optimal choice for the metal layer 2 and the metal pin 9 is the GH4175 material.

[0023] In this embodiment, the number of the first pin holes 7 on the non-working surface 5 of the CMC blade tenon 1 is determined as follows:

[0024] Calculate the loads on the working surface 3 and the non-working surface 5 of the CMC blade according to the service conditions of the CMC blade. According to the loads on the working surface 3 and the non-working surface 5 of the CMC blade, use the formula to calculate the number of the first pin holes 7 on the non-working surface 5; where, F is the centrifugal force of the blade under the engine working condition, θ is the angle between the non-working surface 5 of the tenon and the centrifugal force of the blade, and σ0 is the yield strength of the metal pin 9 material. Selecting the yield strength of the metal pin 9 material to calculate the number of the metal pins 9 can avoid the problem of needing to open more pin holes when calculating with the yield strength of the CMC material, ensuring the overall strength of the CMC blade tenon 1.

[0025] To ensure that the stress between the working surface 3 of the CMC blade tenon 1 and the first contact layer 4 of the metal layer 2 meets the design requirements, the contact area between the working surface 3 and the first contact layer 4 in this embodiment is determined by the formula ; where, F is the centrifugal force of the blade under the engine working condition, α is the angle between the working surface 3 of the tenon and the centrifugal force of the blade, and σ0 is the yield strength of the metal pin 9 material.

[0026] In this embodiment, a vapor deposition layer is provided between the outer wall of the CMC blade tenon 1 and the inner wall of the metal layer 2. The CMC turbine blade and the metal layer 2 are secondarily infiltrated by Chemical vapour infiltration. Under the chemical vapour infiltration process, the metal pin 9, the CMC blade tenon 1 and the metal layer 2 are further connected into a whole, which can further reduce the micro-slip between the CMC blade tenon 1 and the metal layer 2 and weaken the friction and wear problems at the contact interface between the CMC blade and the metal layer 2; The secondary infiltration of the CVI process (chemical vapour deposition can also improve the interface connection effect) can also improve the connection strength between the metal pin 9 and the CMC blade tenon 1 and the metal layer 2.

[0027] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A CMC blade tenon based on metal edging, characterized in that, It includes a metal layer that can be sleeved outside the tenon of the CMC blade. The metal layer includes a first contact layer that fits the working surface of the tenon of the CMC blade and a second contact layer that fits the non-working surface of the tenon of the CMC blade. A first pin hole is formed on the non-working surface, and a second pin hole that cooperates with the first pin hole is formed on the second contact layer. The tenon of the CMC blade is fixedly connected by metal pins inserted into the first pin hole and the second pin hole, and the metal pins are inserted into the first pin hole and the second pin hole in an interference fit manner. The number of the first pin holes on the non-working surface of the tenon of the CMC blade is determined according to the following method: Calculate the loads on the working surface and non-working surface of the CMC blade according to the service conditions of the CMC blade, and calculate the number of the first pin holes on the non-working surface through the formula where F is the centrifugal force of the blade under the engine working condition, θ is the included angle between the non-working surface of the tenon and the centrifugal force of the blade, and σ 0.2 is the yield strength of the metal pin material.

2. The CMC blade tenon based on metal edging according to claim 1, characterized in that, The contact area between the working surface and the first contact layer is determined by the formula ; where F is the centrifugal force of the blade under the engine operating condition, α is the included angle between the working surface of the tenon and the centrifugal force of the blade, and σ 0.2 is the yield strength of the metal pin material.

3. The CMC blade tenon based on metal edging according to claim 1, characterized in that, A vapor deposition layer is provided between the outer wall of the tenon of the CMC blade and the inner wall of the metal layer.

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