Overhung turbine rotor and method of designing the same

Abstract

The application discloses a cantilever turbine rotor and a design method thereof, which is characterized by the following steps: setting the turbine shaft as a hollow shaft, opening a rigidity adjusting structure on a non-torque transmission position of the turbine shaft, reducing the rigidity of the turbine shaft through the rigidity adjusting structure, increasing the elastic deformation amount of the turbine shaft, thereby increasing the maximum range of the given initial pre-tightening force, setting the main parameters of the rigidity adjusting structure affecting the rigidity of the turbine shaft, and locating the non-torque transmission position without affecting the torque transmission, designing corresponding rigidity adjusting structures for different cantilever turbine rotors to adjust the rigidity of the turbine shaft, thereby ensuring that the compression nut can give a suitable initial pre-tightening force when the cantilever turbine rotor is assembled, and the axial fitting surface of the cantilever turbine rotor is in an unloose or non-overload state in the cold state, the hot state or the cold-hot state conversion process, and the cantilever turbine rotor has high practicability and is suitable for wide promotion and application.

Description

Technical Field

[0001] This invention relates to the field of turbine rotor structure design technology, and in particular, to a design method for a cantilever turbine rotor. Furthermore, this invention also relates to a cantilever turbine rotor. Background Technology

[0002] The cantilever turbine rotor meets the core requirements of turboshaft engines for compact structure and ease of maintenance, and is therefore widely used in turboshaft engines. The cantilever turbine rotor is not only a crucial component of a turboshaft engine, but its operational safety and reliability directly affect the stable operation of the turboshaft engine and even the flight safety of the aircraft. Because the preload required for cantilever turbine rotors varies in different models of turboshaft engines, the current preload setting for cantilever turbine rotors mainly depends on the clamping nut installed at the turbine shaft end. When the clamping nut applies the preload, it causes axial elastic deformation at the turbine shaft end. However, the axial elastic deformation of existing turbine shafts is relatively small, which can lead to situations where the clamping nut cannot apply a suitable initial preload during assembly. Since the cantilever turbine rotor is assembled in a cold state and operates in a hot state, if the initial preload is too small during the transition from the cold state to the hot state, the axial contact surface of the rotor will detach due to lack of clamping, causing a malfunction in the turboshaft engine. If the initial preload is too large, the axial contact surface of the rotor will be damaged due to excessive load during operation, also causing a malfunction in the turboshaft engine. Summary of the Invention

[0003] This invention provides a cantilever turbine rotor and its design method to solve the technical problem that existing cantilever turbine rotors are prone to failure to provide a suitable initial preload, resulting in loosening or overload of the axial contact surface during operation.

[0004] According to one aspect of the present invention, a design method for a cantilever turbine rotor is provided, for designing a cantilever turbine rotor including a turbine shaft. The design method includes the following steps: S1: setting the turbine shaft as a hollow shaft, and opening a stiffness adjustment structure on the non-torsion transmission part of the turbine shaft, wherein the stiffness adjustment structure includes n adjustment holes spaced circumferentially on the turbine shaft, the adjustment holes communicating with the inner cavity of the turbine shaft, each adjustment hole occupying a circumferential angle θ relative to the axis of the turbine shaft, and n being an integer greater than 1; S2: constructing a first relational formula relating the initial preload, the maximum relaxation force, and the tightness reserve coefficient of the cantilever turbine rotor; S3: constructing a second relational formula relating the cantilever turbine rotor. The initial preload of the rotor, the maximum clamping force of the cantilever turbine rotor, the yield tensile force of the turbine shaft, and the yield safety factor of the turbine shaft; S4: Construct a third relation relating the yield tensile force of the turbine shaft, the yield strength of the turbine shaft material, and the minimum cross-sectional area of ​​the turbine shaft; S5: Construct a fourth relation relating the minimum cross-sectional area of ​​the turbine shaft, the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, the inner diameter of the turbine shaft, and the outer diameter of the turbine shaft; S6: Derive a fifth relation through the first, second, third, and fourth relations, and use the fifth relation to determine the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, thereby determining the number of adjustment holes n and the circumferential occupancy angle θ of the adjustment holes relative to the turbine shaft axis.

[0005] As a further improvement to the above technical solution:

[0006] Furthermore, the first relation is:

[0007] ;

[0008] In the formula, Let A be the initial preload of the cantilever turbine rotor, and let A be the tightness reserve coefficient. This represents the maximum relaxation force of the cantilever turbine rotor.

[0009] Furthermore, the second relation is:

[0010] ;

[0011] In the formula, This represents the maximum clamping force of the cantilever turbine rotor. B is the yield tensile force of the turbine shaft, and B is the yield safety factor of the turbine shaft.

[0012] Furthermore, the third relation is:

[0013] ;

[0014] In the formula, The yield strength of the turbine shaft material. This represents the minimum cross-sectional area of ​​the turbine shaft.

[0015] Furthermore, the fourth relation is:

[0016] ;

[0017] In the formula, The inner diameter of the turbine shaft. This is the outer diameter of the turbine shaft.

[0018] Furthermore, after step S6, the process includes the step of constructing a sixth relation to determine whether the initial preload was applied properly during assembly. The sixth relation is as follows:

[0019] ;

[0020] In the formula, ΔL is the elastic elongation of the turbine shaft. The axial length of the adjustment hole is given, and E is the elastic modulus of the turbine shaft. This represents the minimum cross-sectional area of ​​the turbine shaft.

[0021] Furthermore, between steps S3 and S4, there is an additional step: constructing a seventh relation to determine whether the turbine shaft yield safety factor B meets the design requirements. The seventh relation is as follows:

[0022] ;

[0023] In the formula, , The yield strength of the turbine shaft material. This represents the maximum equivalent stress on the turbine shaft.

[0024] According to another aspect of the present invention, a cantilever turbine rotor is also provided, which adopts the above-described cantilever turbine rotor design method.

[0025] Furthermore, the cantilever turbine rotor also includes a clamping nut, a first-stage turbine rotor, and a second-stage turbine rotor that are sequentially sleeved on the outside of the turbine shaft along the axial direction. The clamping nut is used to apply preload along the axial direction to sequentially clamp the first-stage turbine rotor and the second-stage turbine rotor. The axial position of the stiffness adjustment structure is located between the first-stage turbine rotor and the second-stage turbine rotor to guide the airflow.

[0026] Furthermore, the turbine shaft includes a first hollow section, a solid section, and a second hollow section in sequence along the axial direction. The clamping nut, the first-stage turbine rotor, and the second-stage turbine rotor are sleeved on the first hollow section. The first hollow section is provided with a first torque transmission spline for engaging with the spline of the second-stage turbine rotor. The solid section is used to axially abut against the second-stage turbine rotor. The second hollow section is provided with a second torque transmission spline.

[0027] The present invention has the following beneficial effects:

[0028] The design method of the cantilever turbine rotor of the present invention involves setting the turbine shaft as a hollow shaft and establishing a stiffness adjustment structure in the non-torsion transmission part of the turbine shaft. This stiffness adjustment structure reduces the stiffness of the turbine shaft, increases its elastic deformation, and thus increases the maximum range of the initial preload. The method also sets the main parameters affecting the turbine shaft stiffness of the stiffness adjustment structure, ensuring that its location in the non-torsion transmission part does not affect torque transmission. A first relationship is constructed to correlate the initial preload, maximum relaxation force, and tightness reserve coefficient of the cantilever turbine rotor to determine the range of the initial preload value. A second relationship is constructed to correlate the initial preload, maximum clamping force, turbine shaft yield tensile force, and turbine shaft yield safety factor, thus linking the initial preload and turbine shaft yield tensile force. A third relationship is constructed to correlate the turbine shaft yield tensile force, turbine shaft material yield strength, and minimum cross-sectional area, thus linking the turbine shaft yield tensile force and minimum cross-sectional area. The fourth relation relates the minimum cross-sectional area of ​​the turbine shaft, the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, the inner diameter of the turbine shaft, and the outer diameter of the turbine shaft, thus correlating the minimum cross-sectional area of ​​the turbine shaft and the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis. The fifth relation is derived from the first, second, third, and fourth relations, which determines the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, thereby determining the number of adjustment holes n and the circumferential occupancy angle θ of the adjustment holes relative to the turbine shaft axis. This establishes the main parameters affecting the stiffness of the turbine shaft. Compared to existing technologies, this solution designs corresponding stiffening structures to adjust the rigidity of the turbine shaft for different cantilever turbine rotors, increasing the axial elastic deformation of the turbine shaft. This ensures that the clamping nut can provide a suitable initial preload during the assembly of the cantilever turbine rotor, ensuring that the axial contact surface of the cantilever turbine rotor remains in a non-loose or overloaded state during cold, hot, or cold-hot transitions. It is highly practical and suitable for widespread promotion and application.

[0029] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 This is a flowchart illustrating the steps of a preferred embodiment of the design method for a cantilever turbine rotor of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of a cantilever turbine rotor according to a preferred embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the axial cross-section of the turbine shaft in a cantilever turbine rotor according to a preferred embodiment of the present invention;

[0034] Figure 4 This is a partial structural diagram of the turbine shaft in a cantilever turbine rotor according to a preferred embodiment of the present invention;

[0035] Figure 5 This is a radial cross-sectional view of the part of the turbine shaft stiffening structure in the cantilever turbine rotor of a preferred embodiment of the present invention.

[0036] Legend:

[0037] 10. Turbine shaft; 11. First hollow section; 12. Solid section; 13. Second hollow section; 14. First transmission spline; 15. Second transmission spline; 20. Compression nut; 30. First-stage turbine rotor; 40. Second-stage turbine rotor; 50. Bearing 1; 60. Bearing 2. Detailed Implementation

[0038] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification.

[0039] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used herein may also include the plural forms. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not preclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or that other features, integers, steps, operations, elements, components, and / or groups may be added to the system / method.

[0040] Considering the following description, these and other features of this specification, as well as the operation and function of the related components of the structure, and the economy of assembly and manufacture of the parts, can be significantly improved. All of these form part of this specification with reference to the accompanying drawings. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0041] like Figures 1-5 As shown, the design method for a cantilever turbine rotor in this embodiment is used to design a cantilever turbine rotor, which includes a turbine shaft. The design method includes the following steps: S1: The turbine shaft is set as a hollow shaft, and a stiffness adjustment structure is opened on the non-torsion transmission part of the turbine shaft. The stiffness adjustment structure includes n adjustment holes spaced circumferentially on the turbine shaft. The adjustment holes are connected to the inner cavity of the turbine shaft. The circumferential angle occupied by each adjustment hole relative to the axis of the turbine shaft is θ, and n is an integer greater than 1; S2: A first relational expression is constructed to associate the initial preload, maximum relaxation force, and tightness reserve coefficient of the cantilever turbine rotor; S3: A second relational expression is constructed to associate the initial preload, maximum relaxation force, and tightness reserve coefficient of the cantilever turbine rotor. S4: Construct a third relation relating the turbine shaft yield tensile force, the turbine shaft material yield strength, and the turbine shaft minimum cross-sectional area; S5: Construct a fourth relation relating the turbine shaft minimum cross-sectional area, the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, the turbine shaft inner diameter, and the turbine shaft outer diameter; S6: Derive a fifth relation through the first, second, third, and fourth relations to determine the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, thereby determining the number of adjustment holes n and the circumferential occupancy angle θ of the adjustment holes relative to the turbine shaft axis.

[0042] like Figures 1-5As shown, specifically, the design method of the cantilever turbine rotor of the present invention involves setting the turbine shaft as a hollow shaft and opening a stiffness adjustment structure in the non-torsion transmission part of the turbine shaft to reduce the stiffness of the turbine shaft and increase the elastic deformation of the turbine shaft, thereby increasing the maximum range of the given initial preload. The main parameters affecting the turbine shaft stiffness are set by the stiffness adjustment structure, and its location in the non-torsion transmission part does not affect torque transmission. A first relationship is constructed to correlate the initial preload of the cantilever turbine rotor, the maximum relaxation force of the cantilever turbine rotor, and the tightness reserve coefficient to determine the value range of the initial preload of the cantilever turbine rotor. A second relationship is constructed to correlate the initial preload of the cantilever turbine rotor, the maximum clamping force of the cantilever turbine rotor, the yield tensile force of the turbine shaft, and the yield safety factor of the turbine shaft to correlate the initial preload of the cantilever turbine rotor and the yield tensile force of the turbine shaft. A third relationship is constructed to correlate the yield tensile force of the turbine shaft, the yield strength of the turbine shaft material, and the minimum cross-sectional area of ​​the turbine shaft to correlate the yield tensile force of the turbine shaft and the minimum cross-sectional area of ​​the turbine shaft. By constructing a fourth relational expression to correlate the minimum cross-sectional area of ​​the turbine shaft, the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, the inner diameter of the turbine shaft, and the outer diameter of the turbine shaft, the minimum cross-sectional area of ​​the turbine shaft and the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis are mutually correlated. A fifth relational expression is derived from the first, second, third, and fourth relations to determine the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, thereby determining the number of adjustment holes n and the circumferential occupancy angle θ of the adjustment holes relative to the turbine shaft axis. This achieves the determination of the main parameters affecting the stiffness of the turbine shaft by the stiffening structure. Compared with existing technologies, this scheme designs corresponding stiffening structures to adjust the rigidity of the turbine shaft for different cantilever turbine rotors, increasing the axial elastic deformation of the turbine shaft. This ensures that the clamping nut can provide a suitable initial preload during the assembly of the cantilever turbine rotor, so that the axial contact surface of the cantilever turbine rotor remains in a non-loose or overloaded state during cold, hot, or cold-hot state transitions. It is highly practical and suitable for widespread promotion and application.

[0043] In this embodiment, the first relation is:

[0044] ;

[0045] In the formula, Let A be the initial preload of the cantilever turbine rotor, and let A be the tightness reserve coefficient. This represents the maximum relaxation force of the cantilever turbine rotor.

[0046] Specifically, given the known tightness reserve coefficient A and the maximum relaxation force of the cantilever turbine rotor... In this case, the initial preload of the cantilever turbine rotor can be determined using the first relationship. This provides data support for determining the parameters of the subsequent stiffness adjustment structure, specifically the initial preload of the cantilever turbine rotor as required. This is to determine the specific parameters of the stiffness adjustment structure, thereby ensuring that the clamping nut can provide a suitable initial preload when assembling the cantilever turbine rotor.

[0047] It should be understood that the maximum relaxation force of the cantilever turbine rotor is determined by finite element calculation.

[0048] It should be understood that the specific steps of finite element calculation are well-known to those skilled in the art, and will not be elaborated upon here.

[0049] Alternatively, engineering experience shows that the tightness reserve coefficient A ranges from 1.15 to 2.0.

[0050] It should be understood that the maximum relaxation force of the cantilever turbine rotor refers to the maximum relaxation force that may occur when the cantilever turbine rotor is operating under all working conditions.

[0051] In this embodiment, the second relation is:

[0052] ;

[0053] In the formula, This represents the maximum clamping force of the cantilever turbine rotor. B is the yield tensile force of the turbine shaft, and B is the yield safety factor of the turbine shaft.

[0054] Specifically, given the initial preload of the cantilever turbine rotor... Given the turbine shaft yield safety factor B and the maximum clamping force of the cantilever turbine rotor, the turbine shaft yield tensile force can be determined using the second relationship. This will provide data support for determining the parameters of the subsequent stiffness adjustment structure.

[0055] It should be understood that the maximum clamping force of the cantilever turbine rotor is determined by finite element calculation.

[0056] It should be understood that the maximum clamping force of the cantilever turbine rotor refers to the maximum clamping force that may occur when the cantilever turbine rotor is operating under all working conditions.

[0057] In this embodiment, the third relation is:

[0058] ;

[0059] In the formula, The yield strength of the turbine shaft material. This represents the minimum cross-sectional area of ​​the turbine shaft.

[0060] Specifically, given the known yield tensile force of the turbine shaft and the yield strength of turbine shaft material In this case, the minimum cross-sectional area of ​​the turbine shaft can be determined using the third relation. This will provide data support for determining the parameters of the subsequent stiffness adjustment structure.

[0061] In this embodiment, the fourth relation is:

[0062] ;

[0063] In the formula, The inner diameter of the turbine shaft. This is the outer diameter of the turbine shaft.

[0064] Specifically, given the minimum cross-sectional area of ​​the turbine shaft... Given the inner diameter of the turbine shaft, the circumferential angle occupied by the stiffening structure relative to the turbine shaft axis can be determined using the fourth relationship. .

[0065] In this embodiment, the fifth relation is:

[0066] ;

[0067] Specifically, the circumferential occupancy angle of the turbine shaft axis is directly determined through the fifth relation. The specific range of values ​​can be determined so that the required number of adjustment holes n and the circumferential occupancy angle θ of the adjustment holes relative to the turbine shaft axis can be selected.

[0068] like Figure 3 As shown, in this embodiment, after step S6, the method further includes the step of constructing a sixth relation to evaluate whether the initial preload is applied properly during the assembly process. The sixth relation is as follows:

[0069] ;

[0070] In the formula, ΔL is the elastic elongation of the turbine shaft. The axial length of the adjustment hole is given, and E is the elastic modulus of the turbine shaft. This represents the minimum cross-sectional area of ​​the turbine shaft.

[0071] Specifically, the appropriate elastic elongation ΔL of the turbine shaft under the theoretically given initial preload is calculated using the sixth relation. Then, the elastic elongation ΔL of the turbine shaft is compared with the actual elastic elongation of the turbine shaft during assembly to determine whether the actual given initial preload is appropriate. This facilitates on-site assembly operations and ensures that the initial preload is applied properly.

[0072] It should be understood that during the assembly process, the axial length of the adjusting hole... It can be obtained through measurement.

[0073] In this embodiment, a further step is included between step S3 and step S4:

[0074] A seventh relation is constructed to determine whether the turbine shaft yield safety factor B meets the design requirements. The seventh relation is as follows:

[0075] ;

[0076] In the formula, , The yield strength of the turbine shaft material. This represents the maximum equivalent stress on the turbine shaft.

[0077] Specifically, in the yield strength of the turbine shaft material and turbine shaft maximum equivalent stress It is known that, and satisfies Under these conditions, it can be determined that the turbine shaft yield safety factor B meets the design requirements, thus providing data support for the subsequent determination of stiffness adjustment structure parameters.

[0078] It should be understood that the maximum equivalent stress of the turbine shaft is determined by finite element analysis.

[0079] like Figure 2 As shown, the cantilever turbine rotor of this embodiment adopts the cantilever turbine rotor design method described above. Specifically, the cantilever turbine rotor is designed and obtained by adopting the cantilever turbine rotor design method described above, so as to ensure that the clamping nut can provide a suitable preload during the assembly process of the cantilever turbine rotor, so as to ensure that the cantilever turbine rotor does not loosen or overload during the cold state, hot state and cold-hot state transition, thereby ensuring the working reliability of the cantilever turbine rotor.

[0080] like Figure 2 As shown, in this embodiment, the cantilever turbine rotor also includes a clamping nut 20, a first-stage turbine rotor 30, and a second-stage turbine rotor 40 sequentially sleeved axially outside the turbine shaft 10. The clamping nut 20 is used to apply a preload along the axial direction to sequentially clamp the first-stage turbine rotor 30 and the second-stage turbine rotor 40. The axial position of the stiffness adjustment structure is located between the first-stage turbine rotor 30 and the second-stage turbine rotor 40 to guide airflow. Specifically, by applying a preload along the axial direction with the clamping nut 20 to clamp the first-stage turbine rotor 30 and the second-stage turbine rotor 40 onto the turbine shaft 10, a suitable initial preload can be given. Then, according to the positional requirements of the air system flow rate, the axial position of the stiffness adjustment structure is set between the first-stage turbine rotor 30 and the second-stage turbine rotor 40 so that the adjustment hole acts as a vent to guide airflow.

[0081] Optionally, the vent hole may be elongated, round, directional, or elliptical.

[0082] like Figure 2 As shown, in this embodiment, the turbine shaft 10 includes, along its axial direction, a first hollow section 11, a solid section 12, and a second hollow section 13. A clamping nut 20, a first-stage turbine rotor 30, and a second-stage turbine rotor 40 are fitted onto the first hollow section 11. The first hollow section 11 has a first torque-transmitting spline 14 for spline engagement with the second-stage turbine rotor 40. The solid section 12 is used to axially abut against the second-stage turbine rotor 40. The second hollow section 13 has a second torque-transmitting spline 15. Specifically, the clamping nut 20 clamps the first-stage turbine rotor 30, so that the second-stage turbine rotor 40 axially abuts against the solid section 12 through force transmission. The hollow portions of the first hollow section 11 and the second hollow section 13 are used for ventilation and air intake, while the first torque-transmitting spline 14 and the second torque-transmitting spline 15 are used to transmit torque, realizing force input and output.

[0083] like Figure 2 As shown, optionally, the cantilever turbine rotor also includes a bearing 50 sleeved outside the secondary turbine rotor 40.

[0084] like Figure 2 As shown, optionally, the cantilever turbine rotor also includes a bearing 60 sleeved outside the second transmission spline 15.

[0085] In summary, after reading the detailed disclosure of this specification, those skilled in the art will understand that the foregoing detailed disclosure is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this specification requires various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0086] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, "an embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is to be emphasized and understood that two or more references to "an embodiment" or "an embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, specific features, structures, or characteristics may be suitably combined in one or more embodiments of this specification.

[0087] It should be understood that in the foregoing description of the embodiments in this specification, various features are combined in a single embodiment, drawing, or description for the purpose of simplifying the description and aiding in the understanding of a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may readily identify some of the devices as separate embodiments when reading this specification. That is, the embodiments in this specification can also be understood as an integration of multiple secondary embodiments. It is also valid when each secondary embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

[0088] Finally, it should be understood that the embodiments disclosed in this specification are illustrative of the principles of the embodiments described in this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can implement the applications in this specification using alternative configurations based on the embodiments in this specification. Therefore, the embodiments in this specification are not limited to the embodiments precisely described in the applications.

Claims

1. A design method for a cantilever turbine rotor, used to design a cantilever turbine rotor, the cantilever turbine rotor including a turbine shaft, characterized in that, The design methodology includes the following steps: S1: Set the turbine shaft as a hollow shaft and open a stiffness adjustment structure on the non-torsion transmission part of the turbine shaft. The stiffness adjustment structure includes n adjustment holes that are opened circumferentially on the turbine shaft. The adjustment holes are connected to the inner cavity of the turbine shaft. The circumferential angle occupied by each adjustment hole relative to the axis of the turbine shaft is θ, and n is an integer greater than 1. S2: Construct the first relational formula relating the initial preload of the cantilever turbine rotor, the maximum relaxation force of the cantilever turbine rotor, and the tightness reserve coefficient; S3: Construct the second relational formula to associate the initial preload of the cantilever turbine rotor, the maximum clamping force of the cantilever turbine rotor, the yield tensile force of the turbine shaft, and the yield safety factor of the turbine shaft; S4: Construct a third relational expression to relate the turbine shaft yield tensile force, turbine shaft material yield strength, and turbine shaft minimum cross-sectional area; S5: Construct the fourth relational formula to associate the minimum cross-sectional area of ​​the turbine shaft, the circumferential occupancy angle of the stiffening structure relative to the turbine shaft axis, the inner diameter of the turbine shaft, and the outer diameter of the turbine shaft; S6: The fifth relation is derived through the first, second, third and fourth relations. The circumferential occupancy angle of the stiffness adjustment structure relative to the turbine shaft axis is determined by the fifth relation, thereby determining the number of adjustment holes n and the circumferential occupancy angle θ of the adjustment holes relative to the turbine shaft axis. The first relation is: ； In the formula, Let A be the initial preload of the cantilever turbine rotor, and let A be the tightness reserve coefficient. This represents the maximum relaxation force of the cantilever turbine rotor. The second relation is: ； In the formula, This represents the maximum clamping force of the cantilever turbine rotor. is the yield tensile force of the turbine shaft, and B is the yield safety factor of the turbine shaft; The third relation is: ； In the formula, The yield strength of the turbine shaft material. This represents the minimum cross-sectional area of ​​the turbine shaft. The fourth relation is: ； In the formula, The inner diameter of the turbine shaft. This is the outer diameter of the turbine shaft.

2. The design method for a cantilever turbine rotor according to claim 1, characterized in that, Step S6 is followed by the following steps: A sixth relation is constructed to determine whether the initial preload is applied properly during assembly. The sixth relation is as follows: ； In the formula, ΔL is the elastic elongation of the turbine shaft. The axial length of the adjustment hole is given, and E is the elastic modulus of the turbine shaft. This represents the minimum cross-sectional area of ​​the turbine shaft.

3. The design method for a cantilever turbine rotor according to claim 1, characterized in that, The steps between step S3 and step S4 include: A seventh relation is constructed to determine whether the turbine shaft yield safety factor B meets the design requirements. The seventh relation is as follows: ； In the formula, , The yield strength of the turbine shaft material. This represents the maximum equivalent stress on the turbine shaft.

4. A cantilever turbine rotor, characterized in that, The design method of the cantilever turbine rotor as described in any one of claims 1-3 is adopted.

5. The cantilever turbine rotor according to claim 4, characterized in that, The cantilever turbine rotor also includes a clamping nut (20), a first-stage turbine rotor (30), and a second-stage turbine rotor (40) that are sequentially sleeved on the outside of the turbine shaft (10) along the axial direction. The clamping nut (20) is used to apply a preload along the axial direction to sequentially clamp the first-stage turbine rotor (30) and the second-stage turbine rotor (40). The axial position of the stiffness adjustment structure is located in the middle of the first-stage turbine rotor (30) and the second-stage turbine rotor (40) to guide the airflow.

6. The cantilever turbine rotor according to claim 5, characterized in that, The turbine shaft (10) includes a first hollow section (11), a solid section (12), and a second hollow section (13) in sequence along the axial direction. The clamping nut (20), the first-stage turbine rotor (30), and the second-stage turbine rotor (40) are sleeved on the first hollow section (11). The first hollow section (11) is provided with a first transmission spline (14) for spline engagement with the second-stage turbine rotor (40). The solid section (12) is used to axially abut against the second-stage turbine rotor (40). The second hollow section (13) is provided with a second transmission spline (15).

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