A hollow fan blade and a design method and system thereof

Abstract

The present application relates to the technical field of fan blade design, and discloses a hollow fan blade and a design method and system thereof, wherein the aerodynamic load, temperature load and vibration load data of the inlet edge and the exhaust edge of the fan stator adjustable blade under a to-be-analyzed working condition are used as working condition load to perform topology optimization of the optimization area of the fan stator adjustable blade; the artificial pseudo density of the optimization area is adjusted in the optimization process to obtain the topology optimization configuration of the optimization area, and finally the topology optimization configuration of the fan stator adjustable blade that meets the maximum first-order natural frequency and the minimum compliance under the to-be-analyzed working condition is selected from the topology optimization configuration of the optimization area as the topology structure of the design area of the fan stator adjustable blade, and auxiliary support is added to the topology structure to form the skeleton structure of the optimization area of the hollow fan stator adjustable blade. The weight of the blade can be significantly reduced on the basis of ensuring the strength and stiffness, and the maximum displacement of the blade tip and the vibration fundamental frequency can meet the design requirements.

Description

Technical Field

[0001] This invention relates to the field of turbine blade design technology, and discloses a hollow fan blade and its design method and system. Background Technology

[0002] Fan blades are located at the very front and outermost edge of an aero-engine. Their main function is to compress the air entering the engine and adjust its flow rate to optimize airflow. Fan blades are critical components of aero-engines, significantly impacting their performance, lifespan, and reliability. Lightweight, high strength, high rigidity, and impact resistance are the main technical goals in the design and manufacture of fan blades.

[0003] To achieve design goals, the structural form and material processing of fan blades have evolved from solid titanium alloy blades to hollow titanium alloy blades and then to resin-based composite blades. Traditional hollow titanium alloy fan blades and resin-based composite fan blades are characterized by high material costs, complex manufacturing processes, and significant design and processing difficulties. Summary of the Invention

[0004] The purpose of this invention is to provide a hollow fan blade and its design method and system, which can significantly reduce the blade weight while ensuring strength and stiffness, and ensure that the maximum displacement of the blade tip and the fundamental frequency of vibration meet the design requirements.

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

[0006] A method for designing hollow fan blades includes:

[0007] Based on the aerodynamic design results of the adjustable blades of the fan stator, a three-dimensional solid geometric model of the adjustable blades of the fan stator with a solid structure is established.

[0008] The three-dimensional solid geometric model is offset inward by 1 to 6% of the radial length of the blade along the radial length direction, and each blade section is offset inward by 5 to 15% of the maximum thickness of the blade section. The area enclosed by the offset curved surface is determined as the optimization area.

[0009] The experiment obtained aerodynamic load, temperature load, and vibration load data of the fan stator adjustable blades on the inlet and exhaust sides under the operating conditions to be analyzed; the natural configuration and relative vibration stress distribution of the fan stator adjustable blades under the operating conditions to be analyzed were obtained through modal analysis.

[0010] Based on the design requirements of the adjustable fan stator blades, topology optimization constraints are set for the optimization region. Aerodynamic loads, temperature loads, and vibration loads under the analyzed operating conditions are applied to the 3D model of the adjustable fan stator blades. The artificial pseudo-density of the optimization region is adjusted to obtain the topology-optimized configuration. The aerodynamic and temperature loads on the inlet and outlet sides of the adjustable fan stator blades are obtained from the aerodynamic and temperature load data of the inlet and outlet sides. The aerodynamic and temperature loads at the position between the inlet and outlet sides are obtained by interpolation. The vibration load at the node with the maximum vibration stress is 1.5 times the vibration load data of the node with the maximum vibration stress under the analyzed operating conditions. The vibration loads at other nodes are the product of the ratio of the vibration stress at that position to the maximum vibration stress and the vibration load at the node with the maximum vibration stress.

[0011] From the topology optimization configuration of the optimization region, the topology optimization configuration that satisfies the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed is selected as the topology of the fan stator adjustable blade design region. Auxiliary support is added to the topology to form the skeleton structure of the hollow fan stator adjustable blade optimization region.

[0012] Furthermore, the method for determining the aerodynamic load, temperature load, and vibration load under the working conditions to be analyzed includes: performing single-condition topology optimization design on the adjustable blades of the fan stator under the conditions of maximum speed, maximum thermal load, and maximum aerodynamic load, respectively, to obtain the compliance under each single working condition, taking the reciprocal of the compliance under each working condition, and normalizing the reciprocal of the compliance to obtain the weight coefficient of the corresponding working condition.

[0013] Based on the aerodynamic load, temperature load, and vibration load of each working condition and their corresponding weighting coefficients, the aerodynamic load, temperature load, and vibration load corresponding to the working condition to be analyzed are obtained by weighting.

[0014] Furthermore, based on the design requirements of the adjustable blades of the fan stator, topology optimization constraints are set for the optimization region, including:

[0015] Apply full constraint to the surfaces of the two mounting shafts of the adjustable blades of the fan stator;

[0016] Set the material accumulation volume of the optimization zone skeleton to be less than 30% of the total volume of the optimization zone;

[0017] The maximum combined stress in the optimization zone does not exceed the yield strength σ of the skeleton material. 0.2 The overall bending stiffness coefficient of the fan stator adjustable blades is greater than 15.

[0018] To achieve the above-mentioned technical effects, the present invention also provides a hollow fan blade design system, comprising:

[0019] The geometric model building module is used to build a three-dimensional solid geometric model of the solid structure of the adjustable blades of the fan stator based on the aerodynamic shape results of the adjustable blades of the fan stator.

[0020] The region division module is used to offset the three-dimensional solid geometric model inward along the radial length of the blade by 1 to 6% of the radial length of the blade, and offset each blade section inward by 5 to 15% of the maximum thickness of the blade section. The region enclosed by the offset curved surface is then defined as the optimization region.

[0021] The data acquisition module is used to obtain the aerodynamic load, temperature load, and vibration load test data of the fan stator adjustable blades on the inlet and exhaust sides under the working conditions to be analyzed; and to obtain the inherent configuration and relative vibration stress distribution of the fan stator adjustable blades under the working conditions to be analyzed through modal analysis.

[0022] The optimization module is used to set topology optimization constraints for the optimization zone based on the design requirements of the adjustable fan stator blades. It applies aerodynamic loads, temperature loads, and vibration loads under the analyzed operating conditions to the 3D model of the adjustable fan stator blades and adjusts the artificial pseudo-density of the optimization zone to obtain the topology-optimized configuration. The aerodynamic and temperature loads on the inlet and outlet edges of the adjustable fan stator blades are obtained from the aerodynamic and temperature load data of the inlet and outlet edges, while the aerodynamic and temperature loads at the position between the inlet and outlet edges are obtained through interpolation. The vibration load at the node with the maximum vibration stress is 1.5 times the vibration load data of the node with the maximum vibration stress under the analyzed operating conditions. The vibration loads at other nodes are the product of the ratio of the vibration stress at that position to the maximum vibration stress and the vibration load at the node with the maximum vibration stress.

[0023] The output module is used to select the topology optimization configuration of the fan stator adjustable blades from the topology optimization configuration of the optimization region, which satisfies the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed, as the topology structure of the fan stator adjustable blade design region. Auxiliary support is added to the topology structure to form the skeleton structure of the hollow fan stator adjustable blade optimization region.

[0024] Furthermore, in the data acquisition module, the method for determining the aerodynamic load, temperature load, and vibration load under the working condition to be analyzed includes: performing single-condition topology optimization design on the adjustable blades of the fan stator under the conditions of maximum speed, maximum thermal load, and maximum aerodynamic load, respectively, to obtain the compliance under each single-condition; taking the reciprocal of the compliance under each condition, and normalizing the reciprocal of the compliance to obtain the weight coefficient of the corresponding working condition; and weighting the aerodynamic load, temperature load, and vibration load of each working condition and the corresponding weight coefficient to obtain the aerodynamic load, temperature load, and vibration load corresponding to the working condition to be analyzed.

[0025] Furthermore, in the optimization module, based on the design requirements of the adjustable blades of the fan stator, topology optimization constraints are set for the optimization region, including:

[0026] Apply full constraint to the surfaces of the two mounting shafts of the adjustable blades of the fan stator;

[0027] Set the material accumulation volume of the optimization zone skeleton to be less than 30% of the total volume of the optimization zone;

[0028] The maximum combined stress in the optimization zone does not exceed the yield strength σ of the skeleton material. 0.2 The overall bending stiffness coefficient of the fan stator adjustable blades is greater than 15.

[0029] To achieve the above-mentioned technical effects, the present invention also provides a hollow fan blade, wherein the internal cavity skeleton structure of the hollow fan blade is designed by the hollow fan blade design method described above.

[0030] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention utilizes the aerodynamic load, temperature load, and vibration load data of the inlet and outlet sides of the adjustable fan stator blades under the analyzed operating conditions as operating condition loads to perform topology optimization of the adjustable fan stator blade optimization region. During the optimization process, the artificial pseudo-density of the optimization region is adjusted to obtain the optimized topology configuration. Finally, the topology configuration that satisfies the largest first-order natural frequency and the smallest compliance under the analyzed operating conditions is selected from the optimized topology configurations as the topology structure of the adjustable fan stator blade design region. Auxiliary supports are added to the topology structure to form a hollow skeleton structure for the optimized fan stator blade region. This significantly reduces blade weight while ensuring strength and stiffness, and ensures that the maximum tip displacement and fundamental vibration frequency meet design requirements. Attached Figure Description

[0031] Figure 1 This is a flowchart of the hollow fan blade design method in Example 1 or 2;

[0032] Figure 2 This is a schematic diagram of the optimized region division of the adjustable blades of the fan stator in Example 1 or 2;

[0033] Figure 3 This is a schematic diagram of the topology of the adjustable blade optimization zone of the fan stator in Example 2;

[0034] Figure 4 This is a schematic diagram of the adjustable blade skeleton structure of the fan stator in Example 2;

[0035] Figure 5 This is a structural block diagram of the hollow fan blade design system in Example 1;

[0036] The module consists of: 1. Optimized region; 2. Non-optimized region; 3. Topology; 4. Skeleton structure; 5. Geometric model construction module; 6. Region division module; 7. Data acquisition module; 8. Optimization module; and 9. Output module. Detailed Implementation

[0037] 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.

[0038] Example 1

[0039] See Figure 1 , Figure 2 and Figure 5 A hollow fan blade design method, comprising:

[0040] Based on the aerodynamic design results of the adjustable blades of the fan stator, a three-dimensional solid geometric model of the adjustable blades of the fan stator with a solid structure is established.

[0041] The three-dimensional solid geometric model is offset inward by 1 to 6% of the radial length of the blade along the radial length direction, and each blade section is offset inward by 5 to 15% of the maximum thickness of the blade section. The area enclosed by the offset curved surface is determined as optimization area 1.

[0042] The experiment obtained aerodynamic load, temperature load, and vibration load data of the fan stator adjustable blades on the inlet and exhaust sides under the operating conditions to be analyzed; the natural configuration and relative vibration stress distribution of the fan stator adjustable blades under the operating conditions to be analyzed were obtained through modal analysis.

[0043] Based on the design requirements of the adjustable fan stator blades, topology optimization constraints are set for optimization region 1. Aerodynamic loads, temperature loads, and vibration loads under the analyzed operating conditions are applied to the 3D model of the adjustable fan stator blades. The artificial pseudo-density of optimization region 1 is adjusted to obtain the topology-optimized configuration of optimization region 1. The aerodynamic and temperature loads on the inlet and outlet sides of the adjustable fan stator blades are obtained based on the aerodynamic and temperature load data of the inlet and outlet sides of the adjustable fan stator blades. The aerodynamic and temperature loads at the position between the inlet and outlet sides are obtained by interpolation. The vibration load at the node with the maximum vibration stress is 1.5 times the vibration load data of the node with the maximum vibration stress under the analyzed operating conditions. The vibration loads at other nodes are the product of the ratio of the vibration stress at that position to the maximum vibration stress and the vibration load at the node with the maximum vibration stress.

[0044] From the topology optimization configuration of optimization zone 1, the topology optimization configuration that satisfies the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed is selected as the topology structure 3 of the fan stator adjustable blade design zone. Auxiliary support is added to the topology structure 3 to form the skeleton structure 4 of the hollow structure of the fan stator adjustable blade optimization zone 1.

[0045] In this embodiment, by offsetting the three-dimensional solid geometric model inward along the radial length direction of the blade by 1-6% of the blade's radial length (the offset value in the radial length direction is a fixed value, and the value range is 1-6% of the blade's radial length), and by offsetting each blade section inward by 5-15% of the maximum thickness of the blade section (the offset value at the blade section is also a fixed value, and the value range is 5-15% of the maximum thickness of the corresponding blade section), the area enclosed by the offset curved surface is determined as optimization zone 1; using the inlet edge and exhaust edge of the adjustable blade of the fan stator under the operating condition to be analyzed... Aerodynamic loads, temperature loads, and vibration loads at the air edge are used as operating loads for topology optimization of the fan stator adjustable blade optimization region 1. During the optimization process, the artificial pseudo-density of the optimization region 1 is adjusted to obtain the topology optimization configuration of optimization region 1. Finally, the topology optimization configuration that satisfies the maximum first-order natural frequency and the minimum compliance under the analyzed operating conditions is selected from the topology optimization configuration of optimization region 1 as the topology structure 3 of the fan stator adjustable blade design region. Auxiliary supports are added to the topology structure 3 to form the hollow skeleton structure 4 of the fan stator adjustable blade optimization region 1. This can significantly reduce the blade weight while ensuring strength and stiffness, and can ensure that the maximum tip displacement and vibration fundamental frequency meet the design requirements.

[0046] In this embodiment, the method for determining the aerodynamic load, temperature load, and vibration load under the operating conditions to be analyzed includes: performing single-condition topology optimization design on the adjustable fan stator blades under the maximum speed condition, maximum thermal load condition, and maximum aerodynamic load condition, respectively, to obtain the compliance under each single condition; taking the reciprocal of the compliance under each condition and normalizing the reciprocal of the compliance to obtain the weight coefficient of the corresponding condition; and weighting the aerodynamic load, temperature load, and vibration load of each condition according to the aerodynamic load, temperature load, and vibration load and the corresponding weight coefficient to obtain the aerodynamic load, temperature load, and vibration load corresponding to the operating condition to be analyzed. This method considers the aerodynamic load, temperature load, and vibration load of the adjustable fan stator blades under different engine operating conditions, achieving multi-objective, multi-condition topology optimization of the adjustable fan stator blades.

[0047] To further ensure that the strength and stiffness of the adjustable blades of the fan stator meet the requirements, the topology optimization constraints in optimization region 1 in this embodiment include:

[0048] 1) Apply full constraint to the surfaces of the two mounting shafts of the adjustable blades of the fan stator;

[0049] 2) Setting the bulk volume of the skeleton material in optimization zone 1 to be less than 30% of the total volume of optimization zone 1 can serve as a guideline for adding auxiliary supports, which can significantly reduce the weight of the blade while ensuring strength and stiffness.

[0050] 3) The maximum combined stress in optimization zone 1 does not exceed the yield strength σ of the skeleton material. 0.2 The overall bending stiffness coefficient of the fan stator adjustable blades is greater than 15.

[0051] Based on the same inventive concept, this embodiment also provides a hollow fan blade design system, including:

[0052] The geometric model construction module 5 is used to establish a three-dimensional solid geometric model of the solid structure of the adjustable blades of the fan stator based on the aerodynamic shape results of the adjustable blades of the fan stator.

[0053] The region division module 6 is used to offset the three-dimensional solid geometric model inward along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and offset each blade section inward by 5 to 15% of the maximum thickness of the blade section. The region enclosed by the offset curved surface is then defined as the optimization region 1.

[0054] Data acquisition module 7 is used to obtain the aerodynamic load, temperature load and vibration load test data of the fan stator adjustable blades on the inlet and exhaust sides of the fan stator adjustable blades under the working conditions to be analyzed; and to obtain the inherent configuration and relative vibration stress distribution of the fan stator adjustable blades under the working conditions to be analyzed through modal analysis.

[0055] Optimization module 8 is used to set the topology optimization constraints of optimization zone 1 according to the design requirements of the adjustable blades of the fan stator. It applies the aerodynamic load, temperature load, and vibration load under the analysis condition to the 3D model of the adjustable blades of the fan stator and adjusts the artificial pseudo density of optimization zone 1 to obtain the topology optimization configuration of optimization zone 1. The aerodynamic load and temperature load on the inlet and outlet sides of the adjustable blades of the fan stator are obtained from the aerodynamic load and temperature load data of the inlet and outlet sides of the adjustable blades of the fan stator. The aerodynamic load and temperature load at the position between the inlet and outlet sides are obtained by interpolation. The vibration load at the node with the maximum vibration stress is 1.5 times the vibration load data of the node with the maximum vibration stress under the analysis condition. The vibration load of the other nodes is the product of the ratio of the vibration stress at that position to the maximum vibration stress and the vibration load at the node with the maximum vibration stress.

[0056] Output module 9 is used to select the topology optimization configuration of the fan stator adjustable blade from the topology optimization configuration of optimization region 1, which satisfies the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed, as the topology structure 3 of the fan stator adjustable blade design region, and add auxiliary support to the topology structure 3 to form the hollow structure skeleton structure 4 of the fan stator adjustable blade optimization region 1.

[0057] Based on the same inventive concept, this embodiment also provides a hollow fan blade, the internal cavity skeleton structure of which is designed by the hollow fan blade design method described above.

[0058] Example 2

[0059] See Figures 1-4 This embodiment uses the multi-objective, multi-condition, and multi-constraint topology optimization process of the adjustable fan stator blade as an example to describe in detail the hollow fan blade design method of the present invention. The specific design steps are as follows:

[0060] Step 1: Based on the aerodynamic design results of the adjustable blades of the fan stator, establish a three-dimensional solid geometric model of the solid structure adjustable blades of the fan stator.

[0061] Step 2: Offset the three-dimensional solid geometric model inward along the radial length of the blade by 1 to 6% of the radial length of the blade, and offset each blade section inward by 5 to 15% of the maximum thickness of the blade section. The area enclosed by the offset curved surface is determined as optimization area 1.

[0062] In this embodiment, the material properties mainly include elastic modulus, density, Poisson's ratio, etc. at different temperatures. The area enclosed by the offset curved surface within 1 mm below the blade base and back surface, 4.5 mm below the leading edge surface, 3 mm below the trailing edge surface, 2 mm from the blade root, and 2 mm from the blade tip of the adjustable blade of the fan stator is defined as optimization region 1. The remaining area is non-optimization region 2. Figure 2 As shown, the hollow internal frame of the blade is made of TC4 titanium alloy, and the material properties of TC4 titanium alloy are incorporated into the optimized design area.

[0063] Step 3: Obtain the aerodynamic load, temperature load, and vibration load data of the adjustable fan stator blades on the inlet and exhaust sides under the operating conditions to be analyzed; obtain the natural configuration and relative vibration stress distribution of the adjustable fan stator blades under the operating conditions to be analyzed through modal analysis.

[0064] In this embodiment, the method for determining the aerodynamic load, temperature load, and vibration load under the operating condition to be analyzed includes: performing single-condition topology optimization design on the adjustable blades of the fan stator under the conditions of maximum speed, maximum thermal load, and maximum aerodynamic load, respectively, to obtain the compliance under each single condition; taking the reciprocal of the compliance under each condition, and normalizing the reciprocal of the compliance to obtain the weight coefficient of the corresponding condition; for example, in this example, the weight coefficients for the three conditions are calculated to be 0.72, 0.16, and 0.12, respectively. Based on the aerodynamic load, temperature load, and vibration load of each condition and the corresponding weight coefficient, weighted summation is performed to obtain the aerodynamic load, temperature load, and vibration load corresponding to the operating condition to be analyzed.

[0065] Step 4: Based on the design requirements of the adjustable fan stator blades, set the topology optimization constraints for optimization zone 1. Apply the aerodynamic load, temperature load, and vibration load under the analyzed operating condition to the 3D model of the adjustable fan stator blades, and adjust the artificial pseudo-density of optimization zone 1 to obtain the topology optimization configuration of optimization zone 1. The aerodynamic and temperature loads on the inlet and exhaust sides of the adjustable fan stator blades are obtained based on the aerodynamic and temperature load data of the inlet and exhaust sides of the adjustable fan stator blades. The aerodynamic and temperature loads at the position between the inlet and exhaust sides are obtained by interpolation. The vibration load at the node with the maximum vibration stress is 1.5 times the vibration load data of the node with the maximum vibration stress under the analyzed operating condition. The vibration loads at other nodes are the product of the ratio of the vibration stress at that position to the maximum vibration stress and the vibration load at the node with the maximum vibration stress.

[0066] The topology optimization constraints for optimization region 1 in this embodiment include:

[0067] 1) Apply full constraint to the surfaces of the two mounting shafts of the adjustable blades of the fan stator;

[0068] 2) Set the material stacking volume of the skeleton in optimization zone 1 to be less than 30% of the total volume of optimization zone 1;

[0069] 3) The maximum combined stress in optimization zone 1 does not exceed the yield strength σ of the skeleton material. 0.2 The overall bending stiffness coefficient of the fan stator adjustable blades is greater than 15.

[0070] Step 5: Select the topology optimization configuration from the topology optimization configuration of the fan stator adjustable blade that satisfies the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed as the topology structure 3 of the fan stator adjustable blade design area. Add auxiliary support to the topology structure 3 to form the skeleton structure 4 of the hollow structure of the fan stator adjustable blade optimization area 1.

[0071] In this embodiment, the finite element software Hypermesh was used to perform optimization calculations on optimization zone 1 of the above-mentioned three-dimensional model, and the results are as follows: Figure 3 , Figure 4 As shown, the blade optimization area 1 has a clear and well-defined force transmission skeleton. The leading edge of the blade extends towards the trailing edge with relatively thin skeleton structures 4, none of which are connected to the trailing edge. A relatively thick transverse skeleton structure 4 exists in the middle of the blade. Overall, the skeleton distribution is reasonable and meets expectations. Then, UGNX software was used to reconstruct the topology-optimized adjustable fan stator blade model, including: thickening the skin on the blade surface to 1mm to obtain a good aerodynamic shape; and arranging the skeleton in the blade optimization design area in a parallel manner and extending it to near the trailing edge of the blade. After reconstruction, a TC4 titanium alloy hollow fan stator adjustable blade configuration with a "skin + skeleton" structure was obtained.

[0072] The structural strength and vibration characteristics of the reconstructed hollow fan stator adjustable blade were evaluated using the finite element software ANSYS. Calculations and analysis showed that the strength reserves of the designed hollow blade under maximum speed, maximum thermal load, and maximum aerodynamic load conditions were 2.11, 1.83, and 5.30, respectively, initially meeting the engineering design requirements and showing a significant improvement over solid blades. The maximum displacements of the blade under the three conditions were 0.77 mm, 2.12 mm, and 0.28 mm, slightly higher than those of solid blades, indicating a slight decrease in stiffness. Furthermore, the first natural frequency of the hollow blade was 243 Hz, significantly higher than the 201 Hz of the solid blade. Additionally, the hollow blade weighed 0.55 kg, a 45% reduction compared to the solid TC4 titanium alloy blade (1.01 kg). The hollowness ratio of the blade's design area reached 75.2%.

[0073] 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 method of designing a hollow fan blade, characterized by, The application relates to a method for designing a fan stator adjustable blade, and belongs to the technical field of fan stator adjustable blades. According to the aerodynamic modeling result of the fan stator adjustable blade, a three-dimensional entity geometric model of the fan stator adjustable blade with a solid structure is established; After the three-dimensional entity geometric model is inwardly offset by 1%-6% of the blade radial length along the blade radial length direction and each blade profile section is inwardly offset by 5%-15% of the maximum thickness of the blade profile section, the region formed by the offset surface is determined as an optimization area; The test obtains the aerodynamic load, temperature load and vibration load data of the fan stator adjustable blade at the inlet edge and the outlet edge of the fan stator adjustable blade under the to-be-analyzed working condition; the inherent mode and the relative vibration stress distribution of the fan stator adjustable blade under the to-be-analyzed working condition are obtained through modal analysis; the determination method of the aerodynamic load, the temperature load and the vibration load under the to-be-analyzed working condition comprises the following steps: single working condition topology optimization design of the fan stator adjustable blade under the maximum rotating speed working condition, the maximum thermal load working condition and the maximum aerodynamic load working condition is respectively carried out, the compliance under each single working condition is obtained, the inverse of the compliance under each working condition is taken, and the inverse of the compliance is normalized to obtain the weight coefficient corresponding to the working condition; according to the aerodynamic load, the temperature load and the vibration load of each working condition and the corresponding weight coefficient, the corresponding aerodynamic load, temperature load and vibration load of the to-be-analyzed working condition are obtained through weighting respectively; According to the design requirements of the fan stator adjustable blade, the topology optimization constraint condition of the optimization area is set, the aerodynamic load, the temperature load and the vibration load under the to-be-analyzed working condition are applied to the three-dimensional model of the fan stator adjustable blade, and the artificial pseudo-density of the optimization area is adjusted to obtain the topology optimization configuration of the optimization area; wherein the aerodynamic load and the temperature load on the inlet edge and the outlet edge of the fan stator adjustable blade are obtained according to the aerodynamic load and the temperature load data of the inlet edge and the outlet edge of the fan stator adjustable blade, the aerodynamic load and the temperature load between the inlet edge and the outlet edge are obtained by interpolation; the vibration load of the maximum vibration stress node is 1.5 times the vibration load data of the maximum vibration stress node under the to-be-analyzed working condition, and the vibration load of the remaining nodes is the product of the vibration stress ratio of the position to the maximum vibration stress and the vibration load of the maximum vibration stress node; The topology optimization configuration of the fan stator adjustable blade which meets the maximum first-order inherent frequency and the minimum compliance under the to-be-analyzed working condition is selected from the topology optimization configuration of the optimization area as the topology structure of the design area of the fan stator adjustable blade, auxiliary supports are added to the topology structure to form the skeleton structure of the optimization area of the fan stator adjustable blade with a hollow structure.

2. The method of designing a hollow fan blade according to claim 1, wherein, According to the design requirements of the fan stator adjustable blade, the topology optimization constraint condition of the optimization area is set, including: Complete constraints are applied to the surfaces of two mounting shafts of the fan stator adjustable blade; The accumulated volume of the skeleton material of the optimization area is set to be less than 30% of the total volume of the optimization area; The maximum synthetic stress of the optimization zone does not exceed the yield strength σ of the skeleton material 0.2 The bending stiffness coefficient of the whole blade of the fan stator adjustable blade is greater than 15.

3. A hollow fan blade design system, characterized by, The geometric model construction module is used for establishing a three-dimensional entity geometric model of the fan stator adjustable blade with a solid structure according to the aerodynamic modeling result of the fan stator adjustable blade; ​ The region division module is configured to offset the three-dimensional entity geometry model inward by 1% to 6% of the blade radial length along the blade radial length direction, offset each airfoil section inward by 5% to 15% of the maximum thickness of the airfoil section, and determine a region formed by offsetting and combining the curved surfaces as an optimization area; The data acquisition module is configured to obtain aerodynamic load, temperature load, and vibration load test data of the fan stator adjustable blade at an inlet edge and an outlet edge of the fan stator adjustable blade under a to-be-analyzed working condition; and obtain inherent mode and relative vibration stress distribution of the fan stator adjustable blade under the to-be-analyzed working condition through modal analysis; and the aerodynamic load, temperature load, and vibration load under the to-be-analyzed working condition are determined by: respectively performing single-working-condition topology optimization design of the fan stator adjustable blade under a maximum rotational speed working condition, a maximum thermal load working condition, and a maximum aerodynamic load working condition, to obtain the compliance of each single working condition, taking the inverse of the compliance of each working condition, and performing normalization processing on the inverse of the compliance to obtain a weight coefficient corresponding to the working condition; and respectively performing weighting according to the aerodynamic load, temperature load, and vibration load of each working condition and the corresponding weight coefficient to obtain the aerodynamic load, temperature load, and vibration load corresponding to the to-be-analyzed working condition; The optimization module is configured to set a topology optimization constraint condition of the optimization area according to a design requirement of the fan stator adjustable blade, apply the aerodynamic load, temperature load, and vibration load under the to-be-analyzed working condition to the three-dimensional model of the fan stator adjustable blade, and adjust an artificial pseudo density of the optimization area, to obtain a topology optimization configuration of the optimization area; wherein the aerodynamic load and temperature load on the inlet edge and the outlet edge of the fan stator adjustable blade are obtained according to aerodynamic load and temperature load data of the inlet edge and the outlet edge of the fan stator adjustable blade, and the aerodynamic load and temperature load at positions between the inlet edge and the outlet edge are obtained by interpolation; the vibration load at the maximum vibration stress node is 1.5 times the vibration load data of the maximum vibration stress node under the to-be-analyzed working condition, and the vibration load of the remaining nodes is the product of a vibration stress ratio of the position relative to the maximum vibration stress and the vibration load at the maximum vibration stress node; The output module is configured to select, from the topology optimization configuration of the optimization area, a topology optimization configuration of the fan stator adjustable blade that meets a maximum first-order inherent frequency and a minimum compliance under the to-be-analyzed working condition, as a topology structure of a design area of the fan stator adjustable blade, and add auxiliary support to the topology structure to form a skeleton structure of the optimization area of the hollow fan stator adjustable blade.

4. The hollow fan blade design system of claim 3, wherein, In the optimization module, setting the topology optimization constraint condition of the optimization area according to the design requirement of the fan stator adjustable blade includes: Applying complete constraints to surfaces of two mounting shafts of the fan stator adjustable blade; Setting a skeleton material accumulation volume of the optimization area to be less than 30% of a total volume of the optimization area; The maximum synthetic stress of the optimization zone does not exceed the yield strength σ of the skeleton material 0.2 The bending stiffness coefficient of the whole blade of the fan stator adjustable blade is greater than 15.

5. A hollow fan blade, characterized by The inner cavity skeleton configuration of the hollow fan blade is designed by the hollow fan blade design method in any one of claims 1-2.

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