Hollow fan blade and design method and system thereof

Abstract

The invention relates to the technical field of fan blade design, and discloses a hollow fan blade and a design method and system thereof. Aerodynamic load, temperature load and vibration load data of an air inlet side and an air outlet side of an adjustable blade of a fan stator under a to-be-analyzed working condition are used as working condition loads; carrying out topological optimization on the adjustable blade optimization area of the fan stator; adjusting the artificial pseudo density of the optimization area in the optimization process to obtain the topological optimization configuration of the optimization area, and finally selecting the topological optimization configuration of the fan stator adjustable blade with the maximum first-order inherent frequency and the minimum flexibility under the to-be-analyzed working condition from the topological optimization configuration of the optimization area as the design area topological structure of the fan stator adjustable blade. And an auxiliary support is added to the topological structure, and the framework structure of the fan stator adjustable blade optimization area of a hollow structure is formed. On the basis of ensuring the strength and the rigidity, the weight of the blade can be obviously reduced, and the maximum displacement of the blade tip and the vibration fundamental frequency can be ensured to meet the design requirements.

Description

Technical Field

[0001] The invention relates to the technical field of turbine blade design, and discloses a hollow fan blade and a design method and system thereof. Background Art

[0002] Fan blades are located at the front and outermost part of the aircraft engine. Their main function is to compress the air entering the aircraft engine, adjust the air flow, and optimize the air flow. Fan blades are key parts in aircraft engines and have a significant impact on the performance, life, and reliability of the engine. Light weight, high strength, good rigidity, and impact resistance are the main technical goals of fan blade design and manufacturing.

[0003] In order to achieve the design goals, the fan blade structure and material technology have gone through a development process from titanium alloy solid blades to titanium alloy hollow blades and then to resin-based composite blades. Traditional titanium alloy hollow fan blades and resin-based composite fan blades have high material costs, complex manufacturing processes, and are difficult to design and process. Summary of the invention

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

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

[0006] A method for designing a hollow fan blade, comprising:

[0007] According to the aerodynamic modeling results of the fan stator adjustable blades, a three-dimensional solid geometric model of the fan stator adjustable blades with a solid structure is established;

[0008] After the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and each blade section is offset inwardly 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 test obtains the aerodynamic load, temperature load and vibration load data of the inlet and exhaust sides of the fan stator adjustable blades under the working conditions to be analyzed; the inherent formation and relative vibration stress distribution of the fan stator adjustable blades under the working conditions to be analyzed are obtained through modal analysis;

[0010] According to the design requirements of the fan stator adjustable blades, the topology optimization constraint conditions of the optimization area are set, the aerodynamic load, temperature load and vibration load under the working condition to be analyzed are applied to the three-dimensional model of the fan stator adjustable blades, and the artificial pseudo-density of the optimization area is adjusted to obtain the topology optimization configuration of the optimization area; the aerodynamic load and temperature load on the intake and exhaust sides of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake and exhaust sides of the fan stator adjustable blades, and the aerodynamic load and temperature load at the position between the intake and exhaust sides 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 of the working condition to be analyzed, and the vibration loads of the remaining nodes are the product of the ratio of the vibration stress at this position to the maximum vibration stress and the vibration load at the maximum vibration stress node;

[0011] From the topology optimization configurations in the optimization area, 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 conditions to be analyzed is selected as the topology structure of the fan stator adjustable blade design area. Auxiliary supports are added to the topology structure to form the skeleton structure of the fan stator adjustable blade optimization area with a hollow structure.

[0012] Furthermore, the method for determining the aerodynamic load, temperature load and vibration load under the working condition to be analyzed includes: performing topological optimization design of the fan stator adjustable blades under the maximum speed working condition, the maximum heat load working condition and the maximum aerodynamic load working condition, 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] According to the aerodynamic load, temperature load and vibration load of each working condition and the corresponding weight coefficient, the aerodynamic load, temperature load and vibration load corresponding to the working condition to be analyzed are weighted respectively.

[0014] Furthermore, according to the design requirements of the fan stator adjustable blades, the topology optimization constraints of the optimization area are set, including:

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

[0016] Set the accumulation volume of skeleton materials in the optimization area to be 30% less than the total volume of the optimization area;

[0017] The maximum composite stress in the optimized area does not exceed the yield strength σ of the skeleton material. 0.2 The bending stiffness coefficient of the entire blade body of the fan stator adjustable blade is greater than 15.

[0018] In order to achieve the above technical effects, the present invention also provides a hollow fan blade design system, comprising:

[0019] A geometric model building module is used to build a three-dimensional solid geometric model of a solid structure fan stator adjustable blade according to the aerodynamic modeling results of the fan stator adjustable blade;

[0020] A region division module is used to determine the region enclosed by the offset curved surface after the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and each blade section is offset inwardly by 5 to 15% of the maximum thickness of the blade section as an optimization region;

[0021] A data acquisition module is used to obtain the aerodynamic load, temperature load and vibration load test data of the inlet side and exhaust side of the fan stator adjustable blade under the working condition to be analyzed; and to obtain the inherent formation and relative vibration stress distribution of the fan stator adjustable blade under the working condition to be analyzed through modal analysis;

[0022] An optimization module is used to set topological optimization constraints of the optimization area according to the design requirements of the fan stator adjustable blades, apply aerodynamic loads, temperature loads and vibration loads under the working condition to be analyzed on the three-dimensional model of the fan stator adjustable blades, and adjust the artificial pseudo-density of the optimization area to obtain the topological optimization configuration of the optimization area; wherein the aerodynamic loads and temperature loads on the intake and exhaust sides of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake and exhaust sides of the fan stator adjustable blades, and the aerodynamic loads and temperature loads at the position between the intake and exhaust sides 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 of the working condition to be analyzed, and the vibration loads of the remaining nodes are the product of the ratio of the vibration stress at the position to the maximum vibration stress and the vibration load at the maximum vibration stress node;

[0023] The output module is used to select the topology optimization configuration of the fan stator adjustable blade from the topology optimization configuration of the optimization area, 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 area, and add auxiliary support to the topology structure to form the skeleton structure of the fan stator adjustable blade optimization area with a hollow structure.

[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 working condition topology optimization design on the fan stator adjustable blades under the maximum speed condition, maximum heat load condition and maximum aerodynamic load condition, respectively, to obtain the compliance under each single working condition, taking the inverse of the compliance under each working condition, and normalizing the inverse of the compliance to obtain the weight coefficient of the corresponding working condition; according to the aerodynamic load, temperature load and vibration load of each working condition and the corresponding weight coefficient, weighted performance is performed to obtain the aerodynamic load, temperature load and vibration load corresponding to the working condition to be analyzed.

[0025] Furthermore, in the optimization module, according to the design requirements of the fan stator adjustable blades, the topology optimization constraint conditions of the optimization area are set, including:

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

[0027] Set the accumulation volume of skeleton materials in the optimization area to be 30% less than the total volume of the optimization area;

[0028] The maximum composite stress in the optimized area does not exceed the yield strength σ of the skeleton material. 0.2 The bending stiffness coefficient of the entire blade body of the fan stator adjustable blade is greater than 15.

[0029] In order to achieve the above technical effects, the present invention also provides a hollow fan blade, and the inner cavity frame structure of the hollow fan blade is obtained by the hollow fan blade design method.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses the aerodynamic load, temperature load and vibration load data of the inlet and exhaust sides of the fan stator adjustable blade under the working condition to be analyzed as the working condition load to perform topological optimization of the fan stator adjustable blade optimization area; during the optimization process, the artificial pseudo-density of the optimization area is adjusted to obtain the topological optimization configuration of the optimization area, and finally the fan stator adjustable blade is selected from the topological optimization configuration of the optimization area to meet the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed as the topological structure of the fan stator adjustable blade design area, and auxiliary support is added to the topological structure to form the skeleton structure of the fan stator adjustable blade optimization area with a hollow structure. The weight of the blade can be significantly reduced on the basis of ensuring strength and stiffness, and the maximum displacement of the blade tip and the fundamental frequency of vibration can be ensured to meet the design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of the hollow fan blade design method in Embodiment 1 or 2;

[0032] Figure 2 A schematic diagram of the division of the optimized area of ​​the fan stator adjustable blades in Example 1 or 2;

[0033] Figure 3 Schematic diagram of the topological structure of the fan stator adjustable blade optimization area in Example 2;

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

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

[0036] Among them, 1. Optimization area; 2. Non-optimization area; 3. Topological structure; 4. Skeleton structure; 5. Geometric model building module; 6. Area division module; 7. Data acquisition module; 8. Optimization module; 9. Output module. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0038] Example 1

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

[0040] According to the aerodynamic modeling results of the fan stator adjustable blades, a three-dimensional solid geometric model of the fan stator adjustable blades with a solid structure is established;

[0041] After the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and each blade section is offset inwardly 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 1;

[0042] The test obtains the aerodynamic load, temperature load and vibration load data of the inlet and exhaust sides of the fan stator adjustable blades under the working conditions to be analyzed; the inherent formation and relative vibration stress distribution of the fan stator adjustable blades under the working conditions to be analyzed are obtained through modal analysis;

[0043] According to the design requirements of the fan stator adjustable blades, the topology optimization constraint conditions of the optimization area 1 are set, the aerodynamic load, temperature load and vibration load under the working condition to be analyzed are applied to the three-dimensional model of the fan stator adjustable blades, and the artificial pseudo-density of the optimization area 1 is adjusted to obtain the topology optimization configuration of the optimization area 1; the aerodynamic load and temperature load on the intake and exhaust sides of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake and exhaust sides of the fan stator adjustable blades, and the aerodynamic load and temperature load at the position between the intake and exhaust sides 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 of the working condition to be analyzed, and the vibration loads of the remaining nodes are the product of the ratio of the vibration stress at this position to the maximum vibration stress and the vibration load at the maximum vibration stress node;

[0044] From the topology optimization configurations of the optimization area 1, 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 is selected as the fan stator adjustable blade design area topology structure 3, and auxiliary supports are added to the topology structure 3 to form the skeleton structure 4 of the fan stator adjustable blade optimization area 1 with a hollow structure.

[0045] In this embodiment, the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade (the offset value in the radial length direction is a fixed value, and the offset value range is 1 to 6% of the radial length of the blade), and each blade section is offset inwardly by 5 to 15% of the maximum thickness of the blade section (the offset value at the blade section is also a fixed value, and the offset value range is 5 to 15% of the maximum thickness of the corresponding blade section), and the area enclosed by the offset curved surface is determined as the optimization area 1; the air inlet edge and the exhaust gas discharge ... The aerodynamic load, temperature load and vibration load data of the air edge are used as working loads to perform topology optimization of the fan stator adjustable blade optimization zone 1; during the optimization process, the artificial pseudo-density of the optimization zone 1 is adjusted to obtain the topology optimization configuration of the optimization zone 1, and finally the fan stator adjustable blade is selected from the topology optimization configuration of the optimization zone 1 to meet the maximum first-order natural frequency and the minimum compliance under the working condition to be analyzed as the fan stator adjustable blade design zone topology structure 3, and auxiliary support is added to the topology structure 3 to form the skeleton structure 4 of the fan stator adjustable blade optimization zone 1 with a hollow structure. The weight of the blade can be significantly reduced on the basis of ensuring strength and stiffness, and the maximum displacement of the blade tip and the fundamental frequency of vibration can be ensured to meet the design requirements.

[0046] In this embodiment, the method for determining the aerodynamic load, temperature load and vibration load under the working condition to be analyzed includes: performing topological optimization design of the fan stator adjustable blades under the maximum speed working condition, the maximum heat load working condition and the maximum aerodynamic load working condition, 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; according to the aerodynamic load, temperature load and vibration load of each working condition and the corresponding weight coefficient, weighting is performed to obtain the aerodynamic load, temperature load and vibration load corresponding to the working condition to be analyzed. The aerodynamic load, temperature load and vibration load of the fan stator adjustable blades under different engine working conditions are considered, and the multi-objective and multi-condition topological optimization of the fan stator adjustable blades is realized.

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

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

[0049] 2) Setting the accumulated volume of the skeleton material in the optimized area 1 to be 30% less than the total volume of the optimized area 1 can be used as a guide for adding auxiliary supports, which can significantly reduce the weight of the blade while ensuring strength and rigidity;

[0050] 3) The maximum composite stress in the optimized area 1 does not exceed the yield strength σ of the skeleton material 0.2 The bending stiffness coefficient of the entire blade body of the fan stator adjustable blade is greater than 15.

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

[0052] A geometric model building module 5 is used to build a three-dimensional solid geometric model of a fan stator adjustable blade with a solid structure according to the aerodynamic modeling result of the fan stator adjustable blade;

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

[0054] The data acquisition module 7 is used to obtain the aerodynamic load, temperature load and vibration load test data of the inlet side and exhaust side of the fan stator adjustable blade under the working condition to be analyzed; and to obtain the inherent formation and relative vibration stress distribution of the fan stator adjustable blade under the working condition to be analyzed through modal analysis;

[0055] The optimization module 8 is used to set the topological optimization constraint conditions of the optimization area 1 according to the design requirements of the fan stator adjustable blades, apply the aerodynamic load, temperature load and vibration load under the working condition to be analyzed on the three-dimensional model of the fan stator adjustable blades, and adjust the artificial pseudo-density of the optimization area 1 to obtain the topological optimization configuration of the optimization area 1; wherein the aerodynamic load and temperature load on the intake side and exhaust side of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake side and exhaust side of the fan stator adjustable blades, and the aerodynamic load and temperature load at the position between the intake side and the exhaust side 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 of the working condition to be analyzed, and the vibration load of the remaining nodes is the product of the ratio of the vibration stress at the position to the maximum vibration stress and the vibration load at the maximum vibration stress node;

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

[0057] Based on the same inventive concept, this embodiment also provides a hollow fan blade, and the inner cavity frame structure of the hollow fan blade is obtained by designing the hollow fan blade design method.

[0058] Example 2

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

[0060] Step 1: According to the aerodynamic modeling results of the fan stator adjustable blades, a three-dimensional solid geometric model of the fan stator adjustable blades with a solid structure is established;

[0061] Step 2: after the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and each blade section is offset inwardly 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 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 fan stator adjustable blade basin and the back surface of the blade, within 4.5 mm below the leading edge surface, within 3 mm below the trailing edge surface, within 2 mm from the blade root, and within 2 mm from the blade tip is determined as the optimized area 1, and the rest is the non-optimized area 2, such as Figure 2 As shown in the figure, the hollow internal skeleton of the blade is made of TC4 titanium alloy, and the material properties of TC4 titanium alloy are given to the optimized design area.

[0063] Step 3: Experimentally obtain the aerodynamic load, temperature load and vibration load data of the inlet side and exhaust side of the fan stator adjustable blade under the working condition to be analyzed; obtain the inherent formation and relative vibration stress distribution of the fan stator adjustable blade under the working condition to be analyzed through modal analysis;

[0064] In this embodiment, the method for determining the aerodynamic load, temperature load and vibration load under the working condition to be analyzed includes: performing topological optimization design of the fan stator adjustable blades under the maximum speed working condition, the maximum heat load working condition and the maximum aerodynamic load working condition, respectively, to obtain the compliance under each single working condition, take the reciprocal of the compliance under each working condition, and normalize the reciprocal of the compliance to obtain the weight coefficient of the corresponding working condition; for example, in this example, the weight coefficients of the three working conditions are calculated to be 0.72, 0.16 and 0.12 respectively. According to the aerodynamic load, temperature load and vibration load of each working condition and the corresponding weight coefficient, weighted aerodynamic load, temperature load and vibration load corresponding to the working condition to be analyzed are obtained respectively.

[0065] Step 4: According to the design requirements of the fan stator adjustable blades, the topology optimization constraint conditions of the optimization area 1 are set, the aerodynamic load, temperature load and vibration load under the working condition to be analyzed are applied to the three-dimensional model of the fan stator adjustable blades, and the artificial pseudo-density of the optimization area 1 is adjusted to obtain the topology optimization configuration of the optimization area 1; wherein the aerodynamic load and temperature load on the intake and exhaust sides of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake and exhaust sides of the fan stator adjustable blades, and the aerodynamic load and temperature load at the position between the intake and exhaust sides 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 of the working condition to be analyzed, and the vibration loads of the remaining nodes are the product of the ratio of the vibration stress at this position to the maximum vibration stress and the vibration load at the maximum vibration stress node;

[0066] In this embodiment, the topology optimization constraints of the optimization zone 1 include:

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

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

[0069] 3) The maximum composite stress in the optimized area 1 does not exceed the yield strength σ of the skeleton material 0.2 The bending stiffness coefficient of the entire blade body of the fan stator adjustable blade is greater than 15.

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

[0071] In this embodiment, the finite element software Hypermesh is used to perform optimization calculation on the above-mentioned three-dimensional model optimization area 1, and the obtained results are as follows: Figure 3 , Figure 4 As shown. It can be seen that the blade optimization area 1 has a clear and definite force transmission skeleton, a relatively thin skeleton structure 4 extends from the leading edge of the blade to the trailing edge and is not connected to the trailing edge, and there is a relatively thick transverse skeleton structure 4 in the middle of the blade. Overall, the skeleton distribution is relatively reasonable and in line with expectations. Then, the UGNX software was used to reconstruct the model of the fan stator adjustable blade after topology optimization, including: thickening the skin on the surface of the blade to 1mm to obtain a good aerodynamic shape, and the skeleton in the blade optimization design area is arranged in parallel and extended to the vicinity of the trailing edge of the blade. After reconstruction, the 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 adjustable stator blades of the hollow fan after model reconstruction were evaluated using the finite element software ANSYS. After calculation and analysis, the strength reserves of the designed hollow blades under the maximum speed condition, the maximum heat load condition and the maximum aerodynamic load condition were 2.11, 1.83 and 5.30 respectively. The strength initially met the engineering design requirements and was significantly improved compared with the strength reserve of the solid blades. The maximum displacements of the blades under the three working conditions were 0.77mm, 2.12mm and 0.28mm respectively, which was slightly increased compared with the maximum displacement of the solid blades, that is, the stiffness of the hollow blades decreased slightly. In addition, the first-order natural frequency of the hollow blade was 243HZ, which was significantly improved compared with the 201HZ of the solid blades. In addition, the weight of the hollow blade was 0.55Kg, which was 45% lighter than the solid structure TC4 titanium alloy blade (1.01Kg). The hollowness rate of the hollow blade body design area reached 75.2%.

[0073] The above are only 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 in the protection scope of the present invention.

Claims

1. A method for designing a hollow fan blade, characterized in that: include: According to the aerodynamic modeling results of the fan stator adjustable blades, a three-dimensional solid geometric model of the fan stator adjustable blades with a solid structure is established; After the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and each blade section is offset inwardly 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; The test obtains the aerodynamic load, temperature load and vibration load data of the inlet and exhaust sides of the fan stator adjustable blades under the working conditions to be analyzed; the inherent formation and relative vibration stress distribution of the fan stator adjustable blades under the working conditions to be analyzed are obtained through modal analysis; According to the design requirements of the fan stator adjustable blades, the topology optimization constraint conditions of the optimization area are set, the aerodynamic load, temperature load and vibration load under the working condition to be analyzed are applied to the three-dimensional model of the fan stator adjustable blades, and the artificial pseudo-density of the optimization area is adjusted to obtain the topology optimization configuration of the optimization area; the aerodynamic load and temperature load on the intake and exhaust sides of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake and exhaust sides of the fan stator adjustable blades, and the aerodynamic load and temperature load at the position between the intake and exhaust sides 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 of the working condition to be analyzed, and the vibration loads of the remaining nodes are the product of the ratio of the vibration stress at this position to the maximum vibration stress and the vibration load at the maximum vibration stress node; From the topology optimization configurations in the optimization area, 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 conditions to be analyzed is selected as the topology structure of the fan stator adjustable blade design area. Auxiliary supports are added to the topology structure to form the skeleton structure of the fan stator adjustable blade optimization area with a hollow structure.

2. The hollow fan blade design method according to claim 1, characterized in that: The method for determining the aerodynamic load, temperature load and vibration load under the working condition to be analyzed includes: performing topological optimization design of the fan stator adjustable blades under the maximum speed working condition, the maximum heat load working condition and the maximum aerodynamic load working condition, 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; According to the aerodynamic load, temperature load and vibration load of each working condition and the corresponding weight coefficient, the aerodynamic load, temperature load and vibration load corresponding to the working condition to be analyzed are weighted respectively.

3. The hollow fan blade design method according to claim 1, characterized in that: According to the design requirements of the fan stator adjustable blades, the topology optimization constraints of the optimization area are set, including: Apply full restraint on the surfaces of the two mounting shafts of the fan stator adjustable blades; Set the accumulation volume of skeleton materials in the optimization area to be 30% less than the total volume of the optimization area; The maximum composite stress in the optimized area does not exceed the yield strength σ of the skeleton material. 0.2 The bending stiffness coefficient of the entire blade body of the fan stator adjustable blade is greater than 15.

4. A hollow fan blade design system, characterized in that: include: A geometric model building module is used to build a three-dimensional solid geometric model of a solid structure fan stator adjustable blade according to the aerodynamic modeling results of the fan stator adjustable blade; A region division module is used to determine the region enclosed by the offset curved surface after the three-dimensional solid geometric model is offset inwardly along the radial length direction of the blade by 1 to 6% of the radial length of the blade, and each blade section is offset inwardly by 5 to 15% of the maximum thickness of the blade section as an optimization region; A data acquisition module is used to obtain the aerodynamic load, temperature load and vibration load test data of the inlet side and exhaust side of the fan stator adjustable blade under the working condition to be analyzed; and to obtain the inherent formation and relative vibration stress distribution of the fan stator adjustable blade under the working condition to be analyzed through modal analysis; An optimization module is used to set topological optimization constraints of the optimization area according to the design requirements of the fan stator adjustable blades, apply aerodynamic loads, temperature loads and vibration loads under the working condition to be analyzed on the three-dimensional model of the fan stator adjustable blades, and adjust the artificial pseudo-density of the optimization area to obtain the topological optimization configuration of the optimization area; wherein the aerodynamic loads and temperature loads on the intake and exhaust sides of the fan stator adjustable blades are obtained according to the aerodynamic load and temperature load data of the intake and exhaust sides of the fan stator adjustable blades, and the aerodynamic loads and temperature loads at the position between the intake and exhaust sides 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 of the working condition to be analyzed, and the vibration loads of the remaining nodes are the product of the ratio of the vibration stress at the position to the maximum vibration stress and the vibration load at the maximum vibration stress node; The output module is used to select the topology optimization configuration of the fan stator adjustable blade from the topology optimization configuration of the optimization area, 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 area, and add auxiliary support to the topology structure to form the skeleton structure of the fan stator adjustable blade optimization area with a hollow structure.

5. The hollow fan blade design system according to claim 4, characterized in that: 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 working condition topology optimization design on the fan stator adjustable blades under the maximum speed condition, the maximum heat load condition and the maximum aerodynamic load condition, respectively, to obtain the compliance under each single working condition, taking the inverse of the compliance under each working condition, and normalizing the inverse of the compliance to obtain the weight coefficient of the corresponding working condition; according to the aerodynamic load, temperature load and vibration load of each working condition and the corresponding weight coefficient, weighted respectively to obtain the aerodynamic load, temperature load and vibration load corresponding to the working condition to be analyzed.

6. The hollow fan blade design system according to claim 4, characterized in that: In the optimization module, according to the design requirements of the fan stator adjustable blades, the topology optimization constraints of the optimization area are set, including: Apply full restraint on the surfaces of the two mounting shafts of the fan stator adjustable blades; Set the accumulation volume of skeleton materials in the optimization area to be 30% less than the total volume of the optimization area; The maximum composite stress in the optimized area does not exceed the yield strength σ of the skeleton material. 0.2 The bending stiffness coefficient of the entire blade body of the fan stator adjustable blade is greater than 15.

7. A hollow fan blade, characterized in that: The inner cavity frame structure of the hollow fan blade is obtained by designing the hollow fan blade according to any one of claims 1-3.

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