Axial compressor rotor parking thermal analysis modeling method

Abstract

The present application relates to the technical field of aero-engine and gas turbine, and discloses a modeling method for parking heat analysis of an axial compressor rotor, comprising: constructing an axial compressor rotor model; intercepting a half-ring model from the model; constructing an equivalent replacement blade model based on a flat plate equivalent replacement, and replacing the blade in situ based on the heat exchange equivalent principle; combining the replaced half-ring equivalent blade with the original rotor disc to form a new axial compressor rotor blade disc model, and performing simulation analysis on the heat dissipation process. The present application replaces the real blade in situ by using the flat plate equivalent model, greatly reduces the number of blade area grids, and greatly improves the speed of unsteady heat simulation solution. Compared with geometric simplification, the equivalent flat plate and the original blade maintain consistent heat exchange area, heat exchange boundary and heat conduction path based on the heat exchange equivalent principle, ensuring the equivalence of blade convective heat dissipation and internal heat conduction; reliable temperature field data support is provided for rotor heat immersion and thermal bending evaluation, effectively improving the analysis accuracy.

Description

Technical Field

[0001] This invention relates to the field of aero-engine and gas turbine technology, specifically to a method for modeling the shutdown thermal analysis of an axial compressor rotor. Background Technology

[0002] The heat dissipation process after an aero-engine or gas turbine shuts down is a complex, long-term, unsteady dynamic process. Post-shutdown thermal analysis of the entire engine is a core supporting step in the thermal immersion and thermal bending analysis and evaluation of the engine rotor.

[0003] Axial compressors have a large number of rotors, and the leading and trailing edges of the rotor blades are very thin. The blade profiles are complex, and the number of meshes they occupy in the construction of the engine shutdown thermal analysis model is enormous. This places extremely high demands on computing memory and computing power. Moreover, long-term unsteady-state calculations take a very long time, which seriously restricts the efficiency of engineering applications and makes it difficult to meet the needs of rapid evaluation. Summary of the Invention

[0004] In view of this, the present invention provides a modeling method for thermal analysis of axial compressor rotor shutdown, in order to solve the problem that axial compressor rotors are numerous, thin and complex, occupy a large number of grids in the construction of engine shutdown thermal analysis model, resulting in long solution time and difficulty in meeting the needs of rapid evaluation.

[0005] In a first aspect, the present invention provides a method for modeling the thermal analysis of an axial compressor rotor shutdown, comprising: Construct an axial flow compressor rotor model; A semi-ring model is extracted from the rotor model of an axial compressor; Mark the angular position of the first blade at the radial high position, and based on the blade disk rotor flow channel end face profile, cut the existing blade body of the entire semi-circle. An equivalent replacement blade model based on flat plate equivalent substitution is constructed, and the blade is replaced in situ starting from the first blade position at the radial high position based on the heat transfer equivalence principle; The replaced semi-ring equivalent blades are combined with the original rotor disk to form a new axial compressor rotor blade disk model, and the heat dissipation process is simulated and analyzed.

[0006] Beneficial effects: This invention uses a flat plate equivalent model to replace the real blades in situ, abandoning the complex three-dimensional curved surface features of the blades and retaining only the simple flat plate structure that satisfies the heat transfer equivalence. The number of meshes in the blade region is greatly reduced, and the overall mesh size of the axial compressor rotor model is significantly reduced. This effectively reduces the hard requirements of simulation on computer memory, graphics card, and processor performance, allowing low-configuration engineering equipment to perform shutdown thermal analysis calculations. The flat plate equivalent replacement simplifies the blade geometry and reduces the number of element solutions. Under the same time step and calculation accuracy, the solution speed of unsteady-state thermal simulation is greatly improved, and the calculation cycle of a single shutdown thermal analysis is significantly shortened. It can quickly output rotor temperature field results, adapting to the engineering needs of rapid comparison and evaluation of multiple engine operating conditions and multiple schemes.

[0007] Moreover, this invention is not simply a geometric simplification. The replacement process takes heat exchange and heat transfer equivalence as the core principle. The equivalent plate maintains the same heat exchange area, heat exchange boundary, and heat conduction path as the original blade. The heat exchange relationship between the rotor disk and the blade, as well as the convective heat dissipation characteristics between the blade and the surrounding airflow, are equivalent to and consistent with the real blade model, ensuring that the blade's convective heat dissipation and internal heat conduction are equivalent. The rotor disk temperature field, radial temperature gradient, and overall heat dissipation evolution law output by the simplified model have controllable deviations compared with the conventional full-blade model calculation results in related technologies. The calculation accuracy will not be reduced due to simplification and replacement. It can provide reliable temperature field data support for rotor thermal immersion and thermal bending evaluation, effectively improving calculation efficiency and analysis accuracy.

[0008] In one optional implementation, when replacing blades in situ based on the principle of heat transfer equivalence, Newton's law of cooling and Fourier's law are followed, and mandatory constraints are set, including: The equivalent replacement blade has a heat dissipation capacity comparable to the original real blade under natural convection conditions, and the heat dissipation capacity includes the heat dissipation capacity along the blade span and the heat dissipation capacity along the chord direction.

[0009] Beneficial Effects: In the in-situ replacement of flat blades, Fourier's law of heat conduction and Newton's law of cooling and convection are used as criteria. Instead of relying on rough simplifications based on experience, quantitative constraints are established based on two heat transfer mechanisms: internal solid heat conduction and wall-borne convective heat dissipation. Compared to modeling methods that only simplify the external shape in related technologies, the equivalence relationship is supported by a complete heat transfer theory. The temperature conduction and convective heat dissipation processes of the equivalent model closely match the physical laws of real blades, ensuring the credibility of the simplified model. The equivalent replacement blade is constrained to have comparable heat dissipation capacity along the blade span and along the chord direction under natural convection conditions to the original real blade. The convective heat transfer in the radial span and circumferential chord direction of the blade is constrained to match the local heat transfer boundaries, avoiding local temperature field deviations caused by single-dimensional equivalence. This restores the differentiated heat dissipation behavior of different regions of the real blade, ensuring that the temperature gradient distribution at the rotor disk-blade connection point and at the radial height of the blade is not distorted. Through forced constraints, the convective heat transfer coefficient, overall heat transfer, and internal solid thermal conductivity temperature field distribution boundaries of the equivalent blade are made consistent with those of the real blade. To ensure that the heat conduction between the rotor disk and blades and the heat exchange rate between the blades and the airflow are consistent with reality in the unsteady shutdown heat dissipation simulation, the rotor temperature evolution curve, radial temperature gradient and circumferential temperature distribution output by the simplified model have controllable deviations. The obtained temperature field data can be directly used for the quantitative evaluation of rotor thermal bending and thermal immersion without introducing calculation deviations due to blade simplification.

[0010] In one alternative implementation, the equivalent replacement blade has the same radial height as the original real blade to ensure that the equivalent blade has the same heat dissipation capacity along the blade span under natural convection as the original real blade. At the same time, it ensures that the radial deformation of the blade is consistent with that of the real blade in the subsequent radial deformation evaluation. The model can be directly applied to the radial deformation evaluation of axial compressors.

[0011] Beneficial Effects: By ensuring that the radial height of the equivalent replacement blade is completely consistent with that of the original real blade, and combining the mandatory equivalence constraints of Newton's law of cooling and Fourier's law, the spanwise heat dissipation characteristics of the blade before and after equivalence are ensured to be consistent, avoiding heat dissipation distortion during the geometric simplification process. The radial height of the blade directly determines the spanwise heat transfer stroke, the airflow convection heat transfer range, and the solid heat conduction path length. It is a core structural parameter affecting the spanwise heat dissipation capacity of the compressor rotor blade. If the radial dimension changes, it will directly lead to a significant shift in the blade's spanwise heat conduction gradient, convection heat transfer area, and airflow heat dissipation boundary, causing distortion in the simulated temperature field distribution. This invention strictly matches the radial height of the original blade, which can restore the heat conduction law and natural convection heat dissipation characteristics of the real blade along the spanwise direction, ensuring that the spanwise heat transfer rate and total heat dissipation of the equivalent blade are comparable to those of the real blade. Combined with the chordal heat dissipation equivalence constraint, accurate equivalence of the blade's heat dissipation capacity is achieved.

[0012] In one optional implementation, the heat transfer area and cross-sectional area of ​​the equivalent replacement blade are consistent with those of the original real blade, so as to ensure that the equivalent blade has the same heat dissipation capacity in the chord direction as the original real blade under natural convection.

[0013] Beneficial Effects: This invention ensures that the heat transfer area and cross-sectional area of ​​the equivalent replacement blade are completely consistent with the original real blade. Combined with the mandatory equivalence constraints of Newton's law of cooling and Fourier's law, it ensures that the chordal heat dissipation characteristics of the blade before and after equivalence are consistent, compensating for the lack of chordal heat dissipation characteristics caused by simple radial dimension matching. The heat transfer area of ​​the blade directly determines the total convective heat transfer between the blade and the surrounding airflow and the range of the heat transfer boundary. The cross-sectional area directly affects the chordal solid thermal conductivity cross-sectional area, heat transfer rate, and internal temperature gradient distribution of the blade. These are core structural parameters determining the chordal heat dissipation capacity of the compressor rotor blade. If the area parameters deviate, it will lead to a shift in the chordal convective heat dissipation and internal thermal conductivity efficiency of the blade, resulting in uneven circumferential temperature distribution and distortion of the overall rotor temperature field simulation. This invention strictly matches the heat transfer area and cross-sectional area of ​​the original blade, accurately restoring the heat conduction law and natural convection heat dissipation characteristics along the chord of the real blade. It ensures that the chordal heat transfer rate and total heat dissipation of the equivalent blade are comparable to those of the real blade. Combined with spanwise dimension equivalence constraints, it achieves precise matching of the spanwise and chordal heat dissipation capabilities of the blade.

[0014] In one alternative implementation, after setting the mandatory constraints, the equivalent geometric dimensions are also derived.

[0015] Beneficial effects: After setting the forced heat transfer constraints, the equivalent geometric dimensions are derived. Based on the heat transfer equivalence criteria of Newton's law of cooling and Fourier's law, the key geometric parameters of the equivalent blade can be quantitatively and accurately solved. This step derives the thickness and width dimensions of the equivalent blade of the flat plate, making the equivalent geometric parameters match the heat conduction and convection heat transfer characteristics of the real blade. While achieving model mesh simplification and improving the efficiency of unsteady-state thermal analysis calculations of the whole machine, it effectively ensures the simulation accuracy of rotor temperature field, temperature gradient, and heat dissipation evolution.

[0016] In one optional implementation, the derivation of the equivalent geometric dimensions includes: Based on relational and relation Under the condition that the heat transfer coefficient and the thermal conductivity of the solid remain unchanged, the size of the equivalent replacement blade is obtained; In the formula Q For heat exchange on the blade surface, h The heat transfer coefficient in the natural convection process. A C For the heat exchange area of ​​the blade, t The blade surface temperature, t ∞The temperature of the incoming fluid. Q＇ For heat transfer inside the blades, λ Thermal conductivity of solids A p Let dx / dt be the cross-sectional area of ​​the blade, and dx / dt be the temperature gradient along the heat conduction direction. C The circumference of the blade cross section. a and b These are the length and width of the rectangular cross-section of the equivalent replacement blade, respectively.

[0017] Beneficial Effects: By utilizing the relationship between convective heat transfer and internal heat conduction of the blades, the equivalent blade geometry is derived while keeping the heat transfer coefficient and solid thermal conductivity constant. By locking the blade heat transfer area, cross-sectional area, and cross-sectional perimeter, the convective heat transfer boundary and internal heat conduction conditions of the blades before and after equivalence are completely consistent. With the blade spanwise height fixed, the length and width of the equivalent rectangular cross-section are solved using the cross-sectional perimeter and area constraints, ensuring that the overall heat transfer and heat dissipation characteristics of the equivalent flat blade accurately match those of a real blade. While ensuring the overall temperature field and heat dissipation accuracy of the rotor, the model mesh size is effectively compressed, significantly reducing the computational power consumption and calculation time for the unsteady-state thermal analysis of the entire machine, thus solving the problem of balancing accuracy and computational efficiency in compressor rotor thermal simulation modeling.

[0018] In one alternative implementation, the equivalent replacement blade with rectangular cross-section features is simulated using a hexahedral mesh.

[0019] Beneficial effects: The equivalent replacement blade adopts a regular rectangular cross section, which can directly generate high-quality hexahedral meshes for simulation calculations. The mesh generation process is simple and the generation speed is fast. Compared with the complex curved surface and thin trailing edge structure of real blades, which require a large number of fine unstructured meshes, the modeling and mesh generation quality and efficiency are greatly improved.

[0020] In one optional implementation, the step of extracting a semi-ring model from the axial compressor rotor model includes: The left and right half-ring models are cut from the compressor rotor model, and the circumferential angle of the cut blade disk is ≥180°.

[0021] Beneficial Effects: In the modeling of axial compressor rotors, using a semi-ring model with a circumferential angle of not less than 180° for truncation modeling can fully utilize the circumferential periodic distribution characteristics of the compressor rotor structure. A semi-ring truncation of 180° or greater can completely cover the periodic heat transfer structure and flow channel heat transfer characteristics of the rotor blades, effectively eliminating the periodic boundary heat transfer cutoff error that easily occurs in small-angle models, and ensuring that the temperature conduction and convective heat dissipation laws of the semi-ring model are completely consistent with those of the full-ring rotor. Moreover, compared to a full-ring model, the semi-ring model can significantly reduce the model size, reduce invalid meshes and computational redundancy, and further reduce the computational load of unsteady-state calculations while ensuring that the accuracy of the whole-machine shutdown thermal analysis simulation is not compromised.

[0022] In an optional implementation, the method further includes: verifying the reliability of the plate equivalent based on the temperature simulation results of the blade changing over time.

[0023] Beneficial effects: By using dynamic temperature simulation data to verify the equivalent flat plate scheme, the temperature curves, radial temperature gradients, and heat dissipation rates of the equivalent model and the actual blade model as a function of downtime can be compared completely. This allows for the determination of the error range of the equivalent modeling and enables closed-loop verification of the equivalent heat transfer logic and geometric constraints of the flat plate. It also confirms the rationality of the spanwise and chordal heat dissipation equivalent constraints and the rules for deriving equivalent dimensions, demonstrating the engineering credibility of the simplified heat transfer equivalent model in the unsteady-state shutdown thermal analysis of aero-engines, thus balancing the efficiency of simulation calculations with the rigor and reliability of temperature assessment results.

[0024] In one alternative implementation, the equivalent replacement blade has the same heat dissipation boundary and temperature evolution law as the original real blade under natural convection conditions.

[0025] Beneficial effects: By constraining the equivalent replacement blades to maintain consistency with the natural convection heat dissipation boundary and temperature evolution law of the original real blades, the unified heat dissipation boundary can ensure that the heat transfer area, heat transfer location and heat transfer coefficient between the blades and the surrounding airflow are completely equivalent, eliminating the heat transfer deviation caused by the simplification of boundary conditions; the consistent temperature evolution law can fully restore the radial and circumferential temperature gradient change trend of the rotor based on the dynamic characteristics of the axial compressor rotor gradually dissipating heat and cooling down over time after shutdown, ensuring the accuracy of the simulation results. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1This is a structural diagram of the actual blades of an axial compressor rotor. Figure 2 This is a structural diagram of the equivalent replacement blade after the equivalent of the axial compressor rotor shutdown thermal analysis modeling method of this invention; Figure 3 This is a schematic diagram of the structure of the axial compressor rotor model constructed by the axial compressor rotor shutdown thermal analysis modeling method of this invention; Figure 4 for Figure 3 A schematic cross-sectional view of the rotor model of a medium-axial flow compressor; Figure 5 This is a magnified schematic diagram of the original real blade structure; Figure 6 This is an enlarged structural schematic diagram of the equivalent replacement blade according to an embodiment of the present invention; Figure 7 for Figure 5 Temperature at points 1-4 and Figure 6 Graph showing the temperature change over time at points 1-4 in the middle section; Figure 8 This is a flowchart illustrating a method for modeling a shutdown thermal analysis of an axial compressor rotor according to an embodiment of the present invention. Figure 9 This is another schematic diagram of the modeling method for thermal analysis of axial compressor rotor shutdown in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 100. Original, genuine leaf blade; 200. Equivalent replacement blades; 300. Rotor disc. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the description of the invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] After an aero-engine and gas turbine shut down, the rotor is in a non-steady-state heat dissipation environment. Its thermal bending and thermal stress distribution directly determine the engine's safety and maintenance cycle. Heat dissipation (natural convection) after engine shutdown exhibits strong circumferential non-uniformity; that is, the hot air in the entire ring state is affected by gravity, resulting in a state where the upper part is hot and the lower part is cold. In related technologies, whole-engine shutdown thermal analysis typically employs a high-precision three-dimensional geometric model with detailed meshing of the compressor blades. To ensure computational accuracy, extremely fine meshes (e.g., local dimensions of 0.1mm-0.2mm) are usually arranged in key areas such as the leading edge, trailing edge, and tip of the blades. Since axial compressor blades typically number in the tens to hundreds, with complex blade profiles (large twist angles, large curvatures) and short chord lengths, the number of meshes becomes extremely large. This results in computational models often reaching tens of millions or even hundreds of millions of units. With limited computing resources, this high mesh size results in extremely long solution times for thermal analysis of a single engine shutdown, often requiring several days. This makes it difficult to perform multi-solution comparisons or rapid iterations in the early stages of engineering design, severely restricting the efficiency of engineering applications and failing to meet the needs of rapid evaluation. Furthermore, the high geometric complexity and massive mesh size of the blades place extremely high demands on computing memory and CPU processing power, making it difficult for ordinary workstations to handle and necessitating the use of high-performance computing clusters. In addition, mesh generation for complex blades is prone to poor mesh quality (such as negative volume and high aspect ratio) in regions like the blade root and tip, affecting the convergence of the solver and the reliability of the calculation results. In view of this, this invention is proposed.

[0033] The following is combined Figures 1 to 9The following describes embodiments of the present invention.

[0034] According to an embodiment of the present invention, in one aspect, a method for modeling the shutdown thermal analysis of an axial compressor rotor is provided, see [link to relevant documentation]. Figure 8 ,include: Construct an axial flow compressor rotor model; A semi-ring model is extracted from the rotor model of an axial compressor; Mark the angular position of the first blade at the radial high position, and based on the blade disk rotor flow channel end face profile, cut the existing blade body of the entire semi-circle. A model of equivalent replacement blade 200 based on flat plate equivalent substitution was constructed, and the blade was replaced in situ starting from the first blade position at the radial high position based on the heat transfer equivalence principle. Figure 1 and Figure 2 The structures of the original real blade 100 and the equivalent replacement blade 200 are given respectively; See Figure 3 The replaced semi-ring equivalent blades are combined with the original rotor disk 300 to form a new axial compressor rotor blade disk model, and the heat dissipation process is simulated and analyzed.

[0035] This invention replaces the actual blades in situ with a flat plate equivalent model, abandoning the complex three-dimensional curved surface features of the blades and retaining only the simple flat plate structure that satisfies the heat transfer equivalence. The number of meshes in the blade region is greatly reduced, and the overall mesh size of the axial compressor rotor model is significantly reduced. This effectively reduces the hard requirements of computer memory, graphics card, and processor performance for simulation, allowing low-configuration engineering equipment to perform shutdown thermal analysis calculations. The flat plate equivalent replacement simplifies the blade geometry and reduces the number of element solutions. Under the same time step and calculation accuracy, the solution speed of unsteady-state thermal simulation is greatly improved, and the calculation cycle of a single shutdown thermal analysis is significantly shortened. It can quickly output rotor temperature field results, adapting to the engineering needs of rapid comparison and evaluation of multiple engine operating conditions and multiple schemes.

[0036] Moreover, this invention is not simply a geometric simplification. The replacement process takes heat exchange and heat transfer equivalence as the core principle. The equivalent plate maintains the same heat exchange area, heat exchange boundary, and heat conduction path as the original blade. The heat exchange relationship between the rotor disk 300 and the blade, as well as the convective heat dissipation characteristics between the blade and the surrounding airflow, are equivalent to and consistent with the real blade model, ensuring that the blade's convective heat dissipation and internal heat conduction are equivalent. The temperature field, radial temperature gradient, and overall heat dissipation evolution law of the rotor disk 300 output by the simplified model have controllable deviations compared with the conventional full-blade model calculation results in related technologies. The calculation accuracy will not be reduced due to simplification and replacement. It can provide reliable temperature field data support for rotor thermal immersion and thermal bending evaluation, effectively improving calculation efficiency and analysis accuracy.

[0037] Furthermore, this invention first extracts a rotor semi-ring model to perform equivalent shearing and replacement of blades. It uses the blade disk flow channel end face profile to uniformly shear the blade entity and completes the plate replacement in an orderly manner from the same reference blade position. By utilizing the circumferential periodicity of the compressor rotor, it is only necessary to perform equivalent simplification on the semi-ring to represent the heat transfer characteristics of the entire ring. This avoids the repetitive modeling operation of simplifying each blade individually and stage by stage, which greatly reduces the workload of three-dimensional modeling. Moreover, the semi-ring equivalent model can directly restore the complete rotor heat transfer state through periodic boundary conditions without the need for additional correction of the circumferential temperature distribution. The modeling process is simple and standardized, reducing the model building and debugging time.

[0038] In some embodiments, see Figure 9 When replacing blades in situ based on the principle of heat transfer equivalence, Newton's law of cooling and Fourier's law are followed, and mandatory constraints are set, including: The equivalent replacement blade 200 has a heat dissipation capacity comparable to the original real blade 100 under natural convection conditions. The heat dissipation capacity includes the heat dissipation capacity along the blade span and the heat dissipation capacity along the chord direction.

[0039] In the in-situ replacement of the flat blade, Fourier's law of heat conduction and Newton's law of cooling and convection are used as the criteria. Instead of relying on rough simplifications based on experience, quantitative constraints are established based on two heat transfer mechanisms: internal heat conduction and wall-to-wall convective heat dissipation. Compared to modeling methods that only simplify the external shape in related technologies, the equivalence relationship is supported by a complete heat transfer theory. The temperature conduction and convective heat dissipation processes of the equivalent model closely match the physical laws of the real blade, ensuring the credibility of the simplified model. The equivalent replacement blade 200 is constrained to have comparable heat dissipation capacity along the blade span and along the chord direction under natural convection conditions to the original real blade 100. The convective heat transfer in the radial span and circumferential chord direction of the blade is constrained to match the local heat transfer boundaries, avoiding local temperature field deviations caused by single-dimensional equivalence. This restores the differentiated heat dissipation behavior of different regions of the real blade 100, ensuring that the temperature gradient distribution at the connection point between the rotor disk 300 and the blade, and at the radial height of the blade, remains accurate. By imposing constraints, the convective heat transfer coefficient, overall heat transfer, and thermal conductivity temperature field distribution boundaries of the equivalent blades are made consistent with those of the real blades. This ensures that in unsteady-state shutdown heat dissipation simulations, the heat conduction between the rotor disk 300 and the blades, and the heat exchange rate between the blades and the airflow, closely match reality. The rotor temperature evolution curve, radial temperature gradient, and circumferential temperature distribution output by the simplified model have controllable deviations. The obtained temperature field data can be directly used for quantitative evaluation of rotor thermal bending and thermal immersion without introducing calculation biases due to blade simplification.

[0040] In some embodiments, the equivalent replacement blade 200 has the same radial height as the original real blade 100 to ensure that the equivalent blade has the same heat dissipation capacity along the blade span under natural convection as the original real blade 100. At the same time, it ensures that the radial deformation is consistent with that of the real blade in the subsequent radial deformation evaluation of the blade. The model can be directly applied to the radial deformation evaluation of axial compressors.

[0041] By ensuring that the radial height of the equivalent replacement blade 200 is completely consistent with that of the original real blade 100, and by combining the mandatory equivalence constraints of Newton's law of cooling and Fourier's law, the spanwise heat dissipation characteristics of the blade before and after equivalence are ensured to be consistent, avoiding heat dissipation distortion during the geometric simplification process. The radial height of the blade directly determines the spanwise heat transfer stroke, the airflow convection heat transfer range, and the solid heat conduction path length. It is a core structural parameter affecting the spanwise heat dissipation capacity of the compressor rotor blade. If the radial dimension changes, it will directly lead to a significant shift in the blade's spanwise heat conduction gradient, convection heat transfer area, and airflow heat dissipation boundary, causing distortion in the simulated temperature field distribution. This invention strictly matches the radial height of the original blade, which can restore the heat conduction law and natural convection heat dissipation characteristics of the real blade 100 along the spanwise direction, ensuring that the spanwise heat transfer rate and total heat dissipation of the equivalent blade are comparable to those of the real blade. Combined with the chordal heat dissipation equivalence constraint, accurate equivalence of the blade's heat dissipation capacity is achieved.

[0042] In some embodiments, the heat transfer area and cross-sectional area of ​​the equivalent replacement blade 200 are consistent with those of the original real blade 100, so as to ensure that the equivalent blade has the same heat dissipation capacity in the chord direction as the original real blade 100 under natural convection.

[0043] To ensure that the heat transfer area and cross-sectional area of ​​the equivalent replacement blade 200 are completely consistent with the original real blade 100, and to ensure that the chordal heat dissipation characteristics of the blade before and after equivalence are consistent by combining the mandatory equivalence constraints of Newton's law of cooling and Fourier's law, this invention compensates for the lack of chordal heat dissipation characteristics caused by simple radial dimension matching. The heat transfer area of ​​the blade directly determines the total convective heat transfer between the blade and the surrounding airflow and the range of the heat transfer boundary. The cross-sectional area directly affects the chordal solid thermal conductivity cross-sectional area, heat transfer rate and internal temperature gradient distribution of the blade. It is a core structural parameter that determines the chordal heat dissipation capacity of the compressor rotor blade. If the area parameters deviate, it will cause the chordal convective heat dissipation and internal thermal conductivity efficiency of the blade to shift, resulting in uneven circumferential temperature distribution of the blade and distortion of the overall temperature field simulation of the rotor. This invention strictly matches the heat transfer area and cross-sectional area of ​​the original blade, which can accurately restore the heat conduction law and natural convection heat dissipation characteristics of the real blade 100 along the chord, ensuring that the chordal heat transfer rate and total heat dissipation of the equivalent blade are comparable to those of the real blade. Combined with the spanwise dimension equivalence constraint, it achieves a precise match between the spanwise and chordal heat dissipation capabilities of the blade.

[0044] In some embodiments, after setting mandatory constraints, the method further includes deriving equivalent geometric dimensions.

[0045] After setting the heat transfer constraints, the equivalent geometric dimensions are derived. Based on the heat transfer equivalence criteria of Newton's law of cooling and Fourier's law, the key geometric parameters of the equivalent blade can be quantitatively and accurately solved. This step derives the thickness and width dimensions of the equivalent blade of the flat plate, making the equivalent geometric parameters match the heat conduction and convection heat transfer characteristics of the real blade. This not only simplifies the model mesh and improves the efficiency of the unsteady-state thermal analysis calculation of the whole machine, but also effectively ensures the simulation accuracy of the rotor temperature field, temperature gradient, and heat dissipation evolution law.

[0046] In some embodiments, the derivation of the equivalent geometric dimensions includes: Based on relational and relation Under the condition that the heat transfer coefficient and the thermal conductivity of the solid remain unchanged, the dimensions of the equivalent replacement blade 200 are obtained. In the formula Q For heat exchange on the blade surface, h The heat transfer coefficient in the natural convection process. A C For the heat exchange area of ​​the blade, t The blade surface temperature, t ∞ The temperature of the incoming fluid. Q＇ For heat transfer inside the blades, λ Thermal conductivity of solids A p Let dx / dt be the cross-sectional area of ​​the blade, and dx / dt be the temperature gradient along the heat conduction direction. C The circumference of the blade cross section. a and b These are the length and width of the rectangular cross-section of the equivalent replacement blade 200, respectively.

[0047] By utilizing the relationship between convective heat transfer and internal heat conduction of the blades, the equivalent blade geometry is derived while keeping the heat transfer coefficient and solid thermal conductivity constant. By locking the blade heat transfer area, cross-sectional area, and cross-sectional perimeter, the convective heat transfer boundary and internal heat conduction conditions of the blades before and after equivalence are completely consistent. With a fixed blade spanwise height, the length and width of the equivalent rectangular cross-section are solved using the cross-sectional perimeter and area constraints, ensuring that the overall heat transfer and heat dissipation characteristics of the equivalent flat blade accurately match those of a real blade. While maintaining the overall temperature field and heat dissipation accuracy of the rotor, the model mesh size is effectively compressed, significantly reducing the computational cost and computation time for the unsteady-state thermal analysis of the entire machine, thus solving the problem of balancing accuracy and computational efficiency in compressor rotor thermal simulation modeling.

[0048] In some embodiments, the equivalent replacement blade 200 with rectangular cross-section features is simulated using a hexahedral mesh.

[0049] The equivalent replacement blade 200 adopts a regular rectangular cross section, which can directly generate high-quality hexahedral meshes for simulation calculations. The mesh generation process is simple and the generation speed is fast. Compared with the complex curved surface and thin trailing edge structure of real blades, which require a large number of fine unstructured meshes, the efficiency of modeling and mesh generation is greatly improved.

[0050] In some embodiments, the step of extracting a semi-ring model from the axial compressor rotor model includes: The left and right half-ring models are cut from the compressor rotor model, and the circumferential angle of the blade disk is ≥180°.

[0051] In the modeling of axial compressor rotors, a semi-ring model with a circumferential angle of not less than 180° is used for truncation modeling, which can fully utilize the circumferential periodic distribution characteristics of the compressor rotor structure. A semi-ring truncation of 180° or greater can completely cover the periodic heat transfer structure and flow channel heat transfer characteristics of the rotor blades, effectively eliminating the periodic boundary heat transfer cutoff error that easily occurs in small-angle models, and ensuring that the temperature conduction and convective heat dissipation laws of the semi-ring model are completely consistent with those of the full-ring rotor. Moreover, compared with the full-ring model, the semi-ring model can significantly reduce the model size, reduce invalid meshes and computational redundancy, and further reduce the computational load of unsteady-state calculations without compromising the accuracy of the overall machine shutdown thermal analysis simulation.

[0052] In some embodiments, the method further includes: verifying the reliability of the equivalent plate based on the temperature simulation results of the blade changing over time.

[0053] By using dynamic temperature simulation data to verify the equivalent flat plate scheme, a complete comparison of the temperature curves, radial temperature gradient, and heat dissipation rate of the equivalent model and the actual blade model over downtime can be made. This allows for the determination of the error range in the equivalent modeling and achieves closed-loop verification of the equivalent heat transfer logic and geometric constraints of the flat plate. It confirms the rationality of the spanwise and chordal heat dissipation equivalent constraints and the derivation rules of equivalent dimensions, demonstrating the engineering credibility of the simplified heat transfer equivalent model in the unsteady-state shutdown thermal analysis of aero-engines, thus balancing the efficiency of simulation calculations with the rigor and reliability of temperature assessment results.

[0054] In some embodiments, the heat dissipation boundary and temperature evolution law of the equivalent replacement blade 200 are consistent with those of the original real blade 100 under natural convection conditions.

[0055] By constraining the equivalent replacement blade 200 to maintain consistency with the original real blade 100 in terms of natural convection heat dissipation boundary and temperature evolution law, the unified heat dissipation boundary ensures that the heat transfer area, heat transfer location and heat transfer coefficient between the blade and the surrounding airflow are completely equivalent, eliminating the heat transfer deviation caused by the simplification of boundary conditions; the consistent temperature evolution law can fully restore the radial and circumferential temperature gradient change trend of the rotor based on the dynamic characteristics of the axial compressor rotor gradually cooling down over time after shutdown, ensuring the accuracy of the simulation results.

[0056] In one embodiment, this invention provides a simplified modeling method for axial compressor rotor structures based on the principle of equivalent heat dissipation. This method utilizes a flat plate model to replace the complex axial compressor blades, aiming to significantly reduce the number of computational meshes and improve mesh quality while ensuring the accuracy of thermal analysis.

[0057] The steps for modeling the thermal analysis of an axial compressor rotor shutdown include: Cut a semi-ring model (left and right half-rings) from the compressor rotor model. If the number of blades is 2N (N is an integer), then the number of blades in the half-ring is N; if the number of blades is 2N+1, then the number of blades in the half-ring is N+1; and ensure that the circumferential angle of the cut blade disk is ≥180°.

[0058] Mark the angular position of the first blade at the radial high position; based on the blade disk rotor flow channel end face profile, the entire semi-circle is sheared to obtain the existing blade entity.

[0059] A blade model based on equivalent plate replacement is established, and in-situ blade replacement is performed starting from the first blade position at the radially high position. The principle and method of equivalent replacement are as follows: (1) The basic principle of equivalent substitution The main constraint of the equivalent replacement is that the equivalent blade should have a heat dissipation capacity comparable to the original real blade 100 under natural convection conditions, including spanwise heat dissipation (radial direction) and chordal heat dissipation (circumferential direction of the blade cross-section). Since the equivalent replacement blade 200 has the same radial height as the original real blade 100, consistent heat dissipation in the spanwise direction is naturally guaranteed. In the chordal direction, to ensure the general applicability of the natural convection heat transfer coefficient model obtained under the original blade model, and to achieve consistent heat dissipation without changing the material, based on Newton's law of cooling and Fourier's law, it can be found that:

[0060] Fluid heat transfer on the blade surface Q Assuming the internal heat transfer remains the same as the original blade, it is only necessary to ensure the heat transfer area of ​​the blade body. Ac and cross-sectional area Ap It should be the same as the original blade.

[0061] (2) Derivation of equivalent geometric dimensions Based on the above assumptions, in the above relational expression t ∞ The inflow temperature is 288.15 K at room temperature. Since the heat transfer distribution and temperature distribution remain constant, the thermal conductivity of the solid is only a physical property parameter. During natural convection, the heat transfer coefficient h ranges from 0 to 30 W / (m²). 2 Within the range of K), its variation is relatively small, thus yielding the blade surface area. A C With cross-sectional area A p constant.

[0062] Assuming the equivalent blade spanwise height remains unchanged before and after, in order to ensure fluid heat transfer... Q Unchanged, due to the surface area of ​​the blade A C ≈C×H (H is the blade spanwise height), the blade cross-sectional perimeter must be maintained. C This remains unchanged, thus ensuring that the boundary conditions for convective heat transfer are consistent.

[0063] Blade cross-sectional perimeter C With cross-sectional area A p Unchanged, that is:

[0064] in a and b Let be the length and width of the flat plate cross-section.

[0065] Under the condition that the heat transfer coefficient and the thermal conductivity of the solid remain unchanged, the dimensions of the equivalent plate of the blade can be obtained.

[0066] The blade is equivalent to a local model of a flat plate, such as Figure 2 As shown. Based on the above simplification measures and the flat plate equivalent blade method, the compressor model is obtained as follows. Figure 3 and Figure 4 As shown.

[0067] It should be noted that the surface area of ​​a blade is the large area in contact with the air, while the cross-sectional area is the size of the solid surface seen when cut.

[0068] The equivalent blade obtained by this method has a length a Similar in chord length to the original blade, but wider. b It is close to the median (or average value) of the inscribed circle along the chord of the blade cross section. Under normal circumstances, it can be 4-10 times larger than the smallest local scale (inscribed circle of the trailing edge) of the original blade. Moreover, the cross-sectional area of ​​the rectangle can be achieved using a fast and efficient hexahedral mesh, thus realizing that the mesh number of the equivalent blade is only 10%-20% of that of the original real blade 100.

[0069] After establishing the blade model based on the equivalent replacement of the flat plate, the replaced semi-ring equivalent blade is combined with the original rotor disk 300 to form a new axial compressor rotor blade disk model, and the heat dissipation process is simulated and analyzed.

[0070] Using a rotor model of an axial compressor as the verification object, meshing was performed on the original model and the equivalent model. The minimum dimensions of the leading and trailing edges of the original real blade were 0.6 mm, while the local minimum dimension needed to be specified in the mesh generation was 0.2 mm. The flat blade constructed using this method has a width of 3.0 mm, and the local minimum dimension can be specified to 1 mm in the mesh generation. With other settings remaining the same, the original model had a mesh size of 7.03 million, while the equivalent flat blade model had only 1.05 million (only 14.9% of the original blade). This shows that the mesh size of the equivalent model is significantly reduced (approximately 85%), significantly improving mesh quality and computational efficiency.

[0071] Feasibility verification and results analysis: Four monitoring points were taken at the same height on the same leaf, as shown in the figures below. Figure 5 and Figure 6 As shown, a comparative analysis of the temperature variation over time at different locations under natural convection conditions is presented. The calculated results and temperature distribution are shown in the figure. Figure 7 As shown.

[0072] Comparing the temperature change curves of four points at the same blade height for both types of blades under natural convection from 0 to 1800 s, the maximum temperature difference between the original blade and the flat blade was 5 K (a deviation of approximately 1.3%) after 100 s of natural convection. After 400 s, the temperatures at the corresponding points in both models were essentially the same (a deviation within 0.5%). This method primarily addresses the issue of excessive mesh counts based on actual blades in parking thermal analysis simulations. This requires that key parameters in the heat dissipation process not deviate too much, meaning the simulated temperature changes of the blade over time should not deviate significantly. In engineering heat transfer analysis, a temperature prediction deviation of less than 5% is generally considered acceptable, and less than 3% is considered highly accurate. This method exhibits a deviation within 1.3%, demonstrating very high accuracy.

[0073] The main source of the deviation lies in the fact that this method is based on a macroscopic equivalent approach, while heat dissipation is highly three-dimensional. The three-dimensional heat dissipation simulation of complex curved surfaces is affected by the blade profile curve, resulting in a certain degree of circumferential non-uniformity in the cross-section (i.e., non-uniformity in the heat dissipation distance and thermal resistance from the heat source to the blade surface). The heat dissipation law of the equivalent rectangular surface is relatively simple, thus leading to some deviation. However, the deviation introduced by this method is acceptable in engineering practice and effectively solves the problem of excessive mesh count, thus possessing significant practical engineering implications.

[0074] The above comparative analysis verifies the feasibility of the flat plate equivalent blade method. This method, while ensuring solution accuracy (within an acceptable engineering range of temperature difference), can significantly reduce the mesh size of the entire engine model, solving the technical challenges of excessive mesh size and long computation time in thermal analysis after aero-engine shutdown.

[0075] This invention discloses a method for performing shutdown thermal analysis of axial compressor blades using a flat plate geometry. While maintaining the cross-sectional area and perimeter of the blades, an equivalent flat plate model is constructed to replace the complex blade geometry. During the equivalence process, constraints are enforced to maintain the surface heat transfer coefficient, local fluid heat transfer, and internal thermal conductivity of the blades. This method can be applied in unsteady-state thermal immersion, thermal bending assessment, and mesh optimization after aero-engine shutdown. By replacing the blades with flat plates, the number of meshes is reduced by more than 80% (from 7.03 million to 1.05 million) at the same accuracy, significantly reducing the demand for hardware resources. The reduced mesh size directly shortens the solution time, reducing a single shutdown thermal analysis from "several days" to "several hours," meeting the needs of rapid engineering evaluation. This method is not only applicable to specific models but can be extended to various axial compressor rotors, demonstrating broad engineering applicability.

[0076] This invention proposes using the consistency of the cross-sectional perimeter and area as the equivalent heat transfer constraint, strictly matching the convective heat transfer area and the solid thermal conduction cross-section, and accurately matching the design of the blade's natural convection heat dissipation scenario. Compared with related technologies that require the acquisition of 3D point clouds and training neural networks to fit the surface, this invention can complete the equivalence only by relying on the geometric parameters of the blade's 2D cross-section, eliminating the steps of surface reconstruction and integral of infinitesimal moments of inertia, and significantly improving the efficiency of pre-modeling. Moreover, this invention significantly compresses the model size while ensuring the accuracy of the temperature field, effectively reducing the amount of mesh and shortening the calculation cycle, especially for unsteady-state heat dissipation scenarios during long-term engine shutdown. Based on Newton's law of cooling and Fourier's law of thermal conductivity, this invention establishes equivalent mathematical constraints, clearly defining the boundary conditions for the invariance of the heat transfer coefficient, heat transfer, and internal temperature field, ensuring the theoretical reliability of the equivalent results.

[0077] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by this application.

Claims

1. A method for modeling the thermal analysis of an axial compressor rotor during shutdown, characterized in that, include: Construct an axial flow compressor rotor model; A semi-ring model is extracted from the rotor model of an axial compressor; Mark the angular position of the first blade at the radial high position, and based on the blade disk rotor flow channel end face profile, cut the existing blade body of the entire semi-circle. Construct an equivalent replacement blade (200) model based on the equivalent substitution of flat plate, and start from the first blade position at the radial high position, and perform in-situ replacement of blades based on the heat transfer equivalence principle; The replaced semi-ring equivalent blades are combined with the original rotor disk (300) to form a new axial compressor rotor blade disk model, and the heat dissipation process is simulated and analyzed.

2. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 1, characterized in that, When replacing blades in situ based on the principle of heat transfer equivalence, Newton's law of cooling and Fourier's law are followed, and mandatory constraints are set, including: The equivalent replacement blade (200) has a heat dissipation capacity comparable to the original real blade (100) under natural convection conditions, and the heat dissipation capacity includes heat dissipation capacity along the blade span and heat dissipation capacity along the chord direction.

3. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 2, characterized in that, The equivalent replacement blade (200) has the same radial height as the original real blade (100) to ensure that the equivalent blade has the same heat dissipation capacity along the blade span under natural convection as the original real blade (100).

4. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 2, characterized in that, The heat transfer area and cross-sectional area of ​​the equivalent replacement blade (200) are consistent with those of the original real blade (100) to ensure that the equivalent blade has the same heat dissipation capacity along the chord direction as the original real blade (100) under natural convection.

5. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to any one of claims 2 to 4, characterized in that, After setting mandatory constraints, the process also includes deriving equivalent geometric dimensions.

6. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 5, characterized in that, The derivation of the equivalent geometric dimensions includes: Based on relational and relation Under the condition that the heat transfer coefficient and the thermal conductivity of the solid remain unchanged, the size of the equivalent replacement blade (200) is obtained; In the formula Q For heat exchange on the blade surface, h The heat transfer coefficient in the natural convection process. A C For the heat exchange area of ​​the blade, t The blade surface temperature, t ∞ The temperature of the incoming fluid. Q＇ For heat transfer inside the blades, λ Thermal conductivity of solids A p Let dx / dt be the cross-sectional area of ​​the blade, and dx / dt be the temperature gradient along the heat conduction direction. C The circumference of the blade cross section. a and b These are the length and width of the rectangular cross section of the equivalent replacement blade (200), respectively.

7. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 1, characterized in that, The equivalent replacement blade (200) with rectangular cross-section features is simulated using a hexahedral mesh.

8. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 1, characterized in that, The process of extracting a semi-ring model from the axial compressor rotor model includes: The left and right half-ring models are cut from the compressor rotor model, and the circumferential angle of the cut blade disk is ≥180°.

9. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 1, characterized in that, The method also includes: verifying the reliability of the plate equivalent based on the temperature simulation results of the blade changing over time.

10. The method for modeling the shutdown thermal analysis of an axial compressor rotor according to claim 1, characterized in that, The heat dissipation boundary and temperature evolution law of the equivalent replacement blade (200) are consistent with those of the original real blade (100) under natural convection conditions.

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