Turbine blade tip clearance passive matching method based on engine requirements

Abstract

The invention discloses a turbine blade tip clearance passive matching method based on engine requirements, and belongs to the technical field of aero-engines, and the turbine blade tip clearance passive matching method comprises the steps that the minimum allowable working clearance is determined; determining a typical tip clearance analysis load spectrum; performing thermal analysis and deformation analysis on the rotor and the stator; according to the deformation results of the rotor and the stator, a blade tip gap change rule is analyzed, and a blade tip gap change rule is obtained; according to different engine requirements, blade tip clearance matching is optimized according to the material, the structure and the cooling form of the cartridge receiver; determining an initial cold-state gap according to the narrow-point gap and the minimum allowable working gap; and carrying out iterative calculation, and determining a final blade tip clearance matching scheme. Turbine rotor deformation and turbine stator deformation can be matched so as to ensure that the turbine blade tip clearance is as small as possible in the focused operation state, that is, the turbine blade tip clearance is reduced as far as possible, the turbine efficiency is improved, and the oil consumption rate is reduced on the premise of ensuring the safety of an engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engines, in particular, to a passive turbine tip clearance matching method based on engine demand. BACKGROUND

[0002] The turbine tip clearance generally refers to the radial distance between the top end face of the engine turbine rotor blade and the outer ring of the turbine stator. Because of the pressure difference between the suction surface and the pressure surface of the rotor blade, the gas at the tip clearance position leaks, thereby significantly reducing the turbine and overall efficiency. Due to the change of engine working conditions, the turbine components will inevitably produce large temperature and stress changes, and the structure, material, thermal load and mechanical load of the turbine stator and the turbine rotor are different, so the turbine rotor and the casing radial deformation mismatch phenomenon will inevitably occur during engine operation, thereby causing the change of the tip clearance, and the change of the tip clearance has an important influence on the performance and reliability of the engine. Excessive tip clearance will lead to a decrease in engine performance, an increase in fuel consumption and a decrease in surge margin; and too small tip clearance may cause blade and casing scraping in severe working conditions with large load changes.

[0003] At present, a suitable cold-state tip clearance is usually adopted according to design experience and test running, which will cause two problems, one is that the turbine tip clearance is designed to be too large, which leads to a decrease in turbine efficiency and substandard engine performance; and the other is that the turbine tip clearance is designed to be too small, which will cause the rotor blade and the stator outer ring to scrape when the engine is in part of the working condition change, which may affect the safe and reliable operation of the engine.

[0004] At present, in small and medium-sized aero-engines, due to the reasons of weight and structure, a simple passive gap control is usually adopted. The passive gap control refers to ensuring the required gap in a certain main state (such as take-off state, maneuvering flight state, etc.) through design cooling and structure, and the gap in other states in the whole flight cycle is matched by the deformation of the rotor and the stator. The passive gap control is indirect, and the engine tip clearance cannot be kept at the best level in the whole flight cycle. Common passive gap control usually adopts the following methods: reducing the assembly gap and improving the sealing; designing a reasonable casing structure to reduce deformation; using wear-resistant coating on the blade top end to reduce tip wear, and using easy-to-wear coating on the outer ring of the casing to facilitate the slight cutting of the blade into the outer ring in the working condition of the engine; and using appropriate materials and cooling to improve the thermal deformation matching of the casing and the rotor. The passive gap control technology has been widely applied in turboshaft, turboprop and small-bypass-ratio engines. Figure 1 A passive control of the gas turbine tip clearance is used for a certain turboshaft engine, and an impact orifice plate is installed on the gas turbine casing. The temperature distribution of the casing is adjusted by designing the orifice diameter, spacing and impact distance of the impact orifice, so as to match the deformation of the casing and the rotor.

[0005] There is no standardized method for matching turbine tip clearance in existing small and medium-sized aero engines. The usual practice is to reduce the assembly clearance and use a wear-prone coating on the gas side of the stator outer ring. Cooling design and material selection are mainly based on the strength and life of the parts. When the engine performance margin is large, detailed tip clearance matching design is not carried out, resulting in a certain amount of performance waste. Summary of the Invention

[0006] In view of at least one of the above technical problems, this application provides a passive matching method for turbine tip clearance based on engine requirements, which can match the turbine rotor deformation and turbine stator deformation to ensure that the turbine tip clearance is as small as possible under the key operating conditions. That is, under the premise of ensuring engine safety, the turbine tip clearance is reduced as much as possible, turbine efficiency is improved and fuel consumption is reduced.

[0007] According to one aspect of this application, a passive matching method for turbine tip clearance based on engine requirements is provided, comprising the following steps: S100: Determine the minimum permissible working clearance according to engine design requirements; S200: Determine the typical tip clearance analysis load spectrum based on the engine's operating scenario; S300: Thermal and deformation analyses of the rotor and stator are performed through three-dimensional simulation to obtain the radial deformation response curves of the turbine rotor and the stator under typical engine operating load spectra. S400: Based on the deformation results of the rotor and stator, the variation law of the blade tip clearance is analyzed to obtain the variation law of the blade tip clearance; S500: The blade tip clearance is optimized for different engine requirements, taking into account the casing material, structure, and cooling method. S600: The anti-scratch casing deformation curve is obtained by adding the minimum allowable working clearance to the radial deformation response curve of the turbine rotor. The actual deformation curve of the casing is obtained by calculation. The intersection of the actual deformation curve of the casing and the anti-scratch casing deformation curve is the narrow point clearance. The initial cold state clearance is determined according to the narrow point clearance and the minimum allowable working clearance. S700: Iteratively calculate steps S500 and S600 until the blade tip clearance meets the engine design requirements, and determine the final blade tip clearance matching scheme.

[0008] In some embodiments of this application, step S100 specifically includes: determining the corresponding minimum allowable blade tip clearance based on each steady-state operating state of the engine, so that the turbine blade tip operating clearance is not less than the minimum allowable blade tip clearance.

[0009] In some embodiments of this application, when determining the minimum permissible working clearance, the influence of at least one of the following factors on rotor and stator deformation is considered: deflection caused by gravity and maneuvering flight gyro torque; ellipticity caused by installation loads; machining errors and eccentricity; bearing radial clearance; rotor imbalance under normal conditions; deformation caused by engine surge; asymmetric thermal and pressure distortion; rotor whirling during hot engine restart; blade twisting and rotor creep elongation.

[0010] In some embodiments of this application, in step S200, the typical tip clearance analysis load spectrum includes the processes of ground slowdown, takeoff, climb, cruise, descent and re-acceleration.

[0011] In some embodiments of this application, step S300 specifically includes: performing rotor thermal analysis and deformation analysis using the three-dimensional finite element method to obtain the temperature field change of the rotor; combining the condition of engine speed change, performing structural deformation analysis on the rotor to obtain the radial deformation result at the rotor blade tip; performing stator thermal analysis and deformation analysis using the three-dimensional finite element method to obtain the temperature field change of the stator; combining the condition of stator pressure load, performing structural deformation analysis on the stator to obtain the radial deformation result at the outer ring of the stator.

[0012] In some embodiments of this application, in step S400, the tip clearance is calculated using the following formula based on the radial deformation results at the rotor blade tip and the radial deformation results at the stator outer ring. delta hot : ; In the formula, It is the initial cold gap. It is the radial deformation at the outer ring of the stator. It is the radial deformation at the rotor blade tip.

[0013] In some embodiments of this application, in step S500, the portion of the actual blade tip clearance that is greater than the minimum allowable working clearance is set as excess clearance. Blade tip clearance matching optimization is performed according to the engine's purpose and requirements. For engines that prioritize fuel efficiency, the blade tip clearance during the cruise phase is matched first, while also taking into account the excess clearance throughout the entire flight cycle. For engines that prioritize maximum power, the blade tip clearance during the maximum power state is matched first.

[0014] In some embodiments of this application, after completing the blade tip clearance matching optimization in step S500, a comprehensive excess clearance is used to measure the clearance matching situation. The comprehensive excess clearance is the integral of the excess clearance over time. The comprehensive excess clearance optimization effect is calculated by weighted summation of the comprehensive excess clearance at each stage of the engine, and the comprehensive excess clearance optimization effect η is obtained. ; ; In the formula, This refers to the overall excess gap before optimization at each stage. The optimized overall excess gap for each stage, The weighting coefficient for the overall excess clearance at each stage, with the subscript i indicating different engine operating states.

[0015] In some embodiments of this application, in step S500, after determining the weighting coefficient of the overall excess clearance at each stage, the clearance matching of the rotor and stator is achieved by changing the casing material, structure, and cooling method. The casing structure is determined in the early stage of design, and then appropriate casing material, air temperature, and cooling method are selected to change the response curve of casing deformation to achieve the corresponding blade tip clearance matching purpose. By comparing the overall excess clearance of different schemes, the optimal parameters are selected, and the overall excess clearance optimization effect is finally determined.

[0016] In some embodiments of this application, in step S600, the narrow point gap must be greater than the minimum allowable working gap in any state of the engine.

[0017] This application has the following beneficial effects: This application proposes a passive turbine tip clearance matching method based on engine requirements. First, it determines the minimum allowable operating clearance according to design requirements. Then, it determines the typical clearance analysis load spectrum based on the engine's operating scenarios. Three-dimensional numerical simulation is used to perform thermal and deformation analyses on the rotor and stator, thereby obtaining the variation law of the turbine tip clearance. Next, the deformation of the rotor and stator is optimized by matching the casing material, structure, and cooling method. The initial cold-state clearance is determined based on the matching between the narrow-point clearance and the minimum allowable operating clearance. It is then judged whether the tip clearance meets the design requirements. If it does, the tip clearance matching scheme is output. This application provides a framework for controlling turbine tip clearance in high-performance aero-engines, taking rotor and stator materials, casing structure, and casing cooling as optimization directions for passive tip clearance matching. Furthermore, it proposes a clearance matching optimization evaluation index based on engines with different applications and requirements, allowing for targeted tip clearance matching optimization according to different needs. This application can perform analysis of turbine tip clearance and optimization of clearance matching for different engine requirements. By using turbine materials and cooling as adjustment means, and combining indicators such as comprehensive excess clearance, the optimized turbine tip clearance is evaluated to achieve better control of turbine tip clearance level, thereby improving turbine efficiency, reducing engine fuel consumption and improving performance. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of a passive control structure for gas turbine tip clearance used in a certain turboshaft engine in the prior art; Figure 2 This is a flowchart illustrating a preferred embodiment of this application; Figure 3 This is a schematic diagram illustrating the variation pattern of the blade tip clearance in a preferred embodiment of this application; Figure 4 This is a schematic diagram of the radial expansion curve of the stator in a preferred embodiment of this application; Figure 5 This is a comparison chart of the tip clearance variation curves of ideally matched and unmatched blades in the preferred embodiments of this application. Detailed Implementation

[0019] Please refer to the instruction manual attached. Figure 2 A passive matching method for turbine blade tip clearance based on engine requirements, characterized by the following steps: S100: Determine the minimum permissible working clearance according to engine design requirements; S200: Determine the typical tip clearance analysis load spectrum based on the engine's operating scenario; S300: Thermal and deformation analyses of the rotor and stator are performed through three-dimensional simulation to obtain the radial deformation response curves of the turbine rotor and the stator under typical engine operating load spectra. S400: Based on the deformation results of the rotor and stator, the variation law of the blade tip clearance is analyzed to obtain the variation law of the blade tip clearance; S500: The blade tip clearance is optimized for different engine requirements, taking into account the casing material, structure, and cooling method. S600: The anti-scratch casing deformation curve is obtained by adding the minimum allowable working clearance to the radial deformation response curve of the turbine rotor. The actual deformation curve of the casing is obtained by calculation. The intersection of the actual deformation curve of the casing and the anti-scratch casing deformation curve is the narrow point clearance. The initial cold state clearance is determined according to the narrow point clearance and the minimum allowable working clearance. S700: Iteratively calculate steps S500 and S600 until the blade tip clearance meets the engine design requirements, and determine the final blade tip clearance matching scheme.

[0020] In some embodiments, step S700 is followed by step S800: outputting a blade tip clearance matching scheme. The output blade tip clearance matching optimization scheme that meets the engine design requirements in step S700 includes a casing optimization scheme, an initial cold clearance adjustment scheme, etc.

[0021] This application proposes a passive turbine tip clearance matching method based on engine requirements. First, it determines the minimum allowable operating clearance according to design requirements. Then, it determines the typical clearance analysis load spectrum based on the engine's operating scenarios. Three-dimensional numerical simulation is used to perform thermal and deformation analyses on the rotor and stator, thereby obtaining the variation law of the turbine tip clearance. Next, the deformation of the rotor and stator is optimized by matching the casing material, structure, and cooling method. The initial cold-state clearance is determined based on the matching between the narrow-point clearance and the minimum allowable operating clearance. It is then judged whether the tip clearance meets the design requirements. If it does, the tip clearance matching scheme is output. This application provides a framework for controlling turbine tip clearance in high-performance aero-engines, taking rotor and stator materials, casing structure, and casing cooling as optimization directions for passive tip clearance matching. Furthermore, it proposes a clearance matching optimization evaluation index based on engines with different applications and requirements, allowing for targeted tip clearance matching optimization according to different needs. This application can perform analysis of turbine tip clearance and optimization of clearance matching for different engine requirements. By using turbine materials and cooling as adjustment means, and combining indicators such as comprehensive excess clearance, the optimized turbine tip clearance is evaluated to achieve better control of turbine tip clearance level, thereby improving turbine efficiency, reducing engine fuel consumption and improving performance.

[0022] Preferably, step S100 specifically includes: determining the corresponding minimum allowable blade tip clearance based on each steady-state operating state of the engine, so that the turbine blade tip operating clearance is not less than the minimum allowable blade tip clearance.

[0023] The term "minimum permissible working clearance" here refers to the minimum allowable blade tip clearance for each steady-state operating condition of the engine. In other words, the turbine blade tip clearance must not be less than the minimum permissible working clearance; otherwise, it may have a harmful effect on the engine. Considering the many factors during engine operation, determining the minimum permissible working clearance can prevent the turbine rotor blade tip from rubbing against the turbine stator outer ring.

[0024] Preferably, when determining the minimum permissible working clearance, the influence of at least one of the following factors on rotor and stator deformation is considered: deflection caused by gravity and gyroscopic torque during maneuvering; ellipticity caused by installation loads; machining errors and eccentricity; bearing radial clearance; rotor imbalance under normal conditions; deformation caused by engine surge; asymmetric thermal and pressure distortion; rotor whirling during hot engine restart; blade twisting and rotor creep elongation.

[0025] It should be noted that the following factors need to be considered: Deflection caused by gravity and gyroscopic torque during maneuvering flight. Gravitational loads and gyroscopic torque during maneuvering cause the rotor to experience a couple at the support, resulting in bending deflection. Ellipticity caused by installation loads must also be considered. The load transmitted from the engine mounting section is distributed across the casing, and uneven circumferential loads lead to casing ellipticity. Manufacturing errors and eccentricity, i.e., eccentricity between the casing and rotor during manufacturing, must also be considered. Bearing radial clearance must be considered, as its presence affects the rotor's position, leading to variations in the clearance between the rotor and casing. Normal rotor imbalance must be considered; under normal conditions, rotor imbalance is unavoidable, resulting in uneven circumferential blade tip clearance. Deformation caused by engine surge must be considered. Asymmetric thermal and pressure distortion, caused by asymmetric thermal and pressure deformation, leads to uneven circumferential clearance. Rotor whirling during hot engine restart must be considered, as the "hot at the top, cold at the bottom" phenomenon during hot start-up causes rotor whirling due to thermal bending. Blade twisting and rotor creep elongation must also be considered.

[0026] Preferably, in step S200, the typical tip clearance analysis load spectrum includes the processes of ground slowdown, takeoff, climb, cruise, descent and re-acceleration.

[0027] It should be noted that when determining the typical tip clearance analysis load spectrum, typical operating states must be selected based on the engine's operating characteristics. For example, the load spectrum should include processes such as ground stagnation, takeoff, climb, cruise, descent, and re-acceleration. The duration of ground stagnation and takeoff is specified according to the actual engine operating scenario. For operating states with longer durations, such as climb and cruise phases, in order to save the overall calculation and analysis time, the climb and cruise times only need to satisfy the rotor temperature stability. The descent and re-acceleration process can be appropriately shortened to simulate the phenomenon of the tip clearance rapidly decreasing during the engine's deceleration and re-acceleration process.

[0028] Preferably, step S300 specifically includes: performing rotor thermal analysis and deformation analysis using the three-dimensional finite element method to obtain the temperature field change of the rotor; combining the condition of engine speed change, performing structural deformation analysis on the rotor to obtain the radial deformation result at the rotor blade tip; performing stator thermal analysis and deformation analysis using the three-dimensional finite element method to obtain the temperature field change of the stator; combining the condition of stator pressure load, performing structural deformation analysis on the stator to obtain the radial deformation result at the outer ring of the stator.

[0029] Understandably, the rotor thermal and deformation analyses are performed using the three-dimensional finite element method. Three-dimensional numerical simulations are used to obtain the rotor's temperature field changes. The temperature field results are then used as input for deformation analysis. Combined with conditions such as engine speed changes, the rotor's structural deformation is analyzed to obtain the radial deformation results at the rotor blade tips. Similarly, the stator thermal and deformation analyses are performed using the three-dimensional finite element method. Three-dimensional numerical simulations are used to obtain the stator's temperature field changes. The temperature field results are then used as input for deformation analysis. Combined with conditions such as stator pressure loads, the stator's structural deformation is analyzed to obtain the radial deformation results of the stator's outer ring (gas combustion surface).

[0030] Preferably, in step S400, the tip clearance is calculated using the following formula based on the radial deformation results at the rotor blade tip and the radial deformation results at the stator outer ring. delta hot : ; In the formula, It is the initial cold gap. It is the radial deformation at the outer ring of the stator. This refers to the radial deformation at the rotor blade tip. Assuming the initial cold clearance is 0, the blade tip clearance variation pattern can be obtained. Please refer to the appendix of the instruction manual. Figure 3 After analyzing the variation law of blade tip clearance and obtaining the radial deformation results of the rotor and stator, the turbine blade tip clearance can be determined by the aforementioned blade tip clearance. delta hot The calculation formula is used to calculate it.

[0031] Preferably, in step S500, the portion of the actual blade tip clearance that is greater than the minimum allowable working clearance is set as the excess clearance. The excess clearance is the difference between the actual blade tip clearance and the minimum allowable working clearance in the corresponding state. The blade tip clearance matching optimization is performed according to the purpose and requirements of the engine. For engines that pursue fuel efficiency, the blade tip clearance during the cruise phase is matched first, while taking into account the excess clearance throughout the entire flight cycle. For engines that pursue maximum power, the blade tip clearance in the maximum power state is matched first.

[0032] It is understandable that step S300 can obtain the radial deformation (expansion) response curve of the turbine rotor and stator under a typical engine operating load spectrum, as shown in the attached figure. Figure 4 As shown, to ensure that the blade tip clearance is greater than the minimum allowable clearance throughout the entire flight mission, the minimum allowable working clearance needs to be added to the rotor deformation curve to obtain the anti-scratch casing deformation curve (i.e., the casing deformation curve required to prevent scratching). This anti-scratch casing deformation curve is the casing deformation (expansion) response curve under ideal conditions with optimal rotor-stator matching. It should be noted that the outer ring is attached to the casing, and the casing deformation curve here is actually the deformation curve of the outer ring.

[0033] Furthermore, the rotor deformation curve and the actual casing deformation curve are superimposed. The blade tip clearance is the difference in radial deformation (expansion) between the two curves. By adjusting the cold clearance, the position of the actual casing deformation curve is changed so that the actual casing deformation curve is higher than the anti-scratch casing deformation curve, while keeping the difference in radial deformation (expansion) between the two curves to a minimum. At this point, the intersection of the two curves is called the minimum clearance point, i.e., the narrow point clearance.

[0034] Please refer to Figure 5 The portion exceeding the minimum permissible working clearance is called excessive clearance, defined as the difference between the blade tip clearance and the minimum permissible clearance for the corresponding state. The goal of blade tip clearance matching is to eliminate excessive clearance in all states. Excess clearance is caused by the mismatch between the casing expansion and the rotor expansion response. To eliminate excessive clearance in all states, the ideal situation is to make the blade tip clearance equal to the minimum permissible clearance, and to ensure that the expansion responses of the casing and rotor are consistent, so that the change in blade tip clearance (the difference between the maximum clearance and the minimum clearance) is 0.

[0035] It should be noted that the actual minimum permissible clearance is not the same in all situations. Generally, the minimum permissible clearance required during takeoff is larger. Figure 5 The minimum allowable clearance can be considered as the larger value of the required clearance under all conditions. In actual clearance matching, it is impossible to make the rotor and stator deform synchronously, that is, the change in blade tip clearance is not zero. Therefore, in actual clearance matching optimization, it is necessary to eliminate excessive clearance according to the engine's purpose and requirements. For engines that pursue fuel efficiency, priority should be given to matching the blade tip clearance during the cruise phase, while also taking into account the excessive clearance throughout the entire flight cycle; for engines that pursue maximum power, priority should be given to matching the blade tip clearance under the maximum power condition.

[0036] Preferably, in step S500, after completing the blade tip clearance matching optimization, the overall excess clearance is used to measure the clearance matching situation. The overall excess clearance is the integral of the excess clearance over time. The overall excess clearance optimization effect is calculated by weighted summation of the overall excess clearance at each stage of the engine, and the overall excess clearance optimization effect η is obtained. ; ; In the formula, This refers to the overall excess gap before optimization at each stage. The optimized overall excess gap for each stage, The weighting coefficient for the overall excess clearance at each stage, with the subscript i indicating different engine operating states.

[0037] Understandably, for civilian engines prioritizing low fuel consumption and good economy, several states with a significant proportion in the engine's operating load spectrum can be selected. The weighting coefficient K is allocated according to the proportion of time for different states, and the overall excess clearance in specific states is optimized accordingly. This prioritizes reducing the turbine tip clearance level in the main operating states across the entire operating load spectrum, thereby minimizing engine fuel consumption. For engines aiming for maximum takeoff power, states with high power demand, such as the maximum takeoff state, can be selected. The weighting coefficient is focused on this state, while other states are assigned weighting coefficients as appropriate, or even not assigned any weighting coefficients, to achieve optimal tip clearance in the maximum takeoff state, thereby increasing engine power and meeting the engine's power requirements in the specified state.

[0038] Preferably, in step S500, after determining the weighting coefficient of the overall excess clearance at each stage, the clearance matching of the rotor and stator is achieved by changing the casing material, structure, and cooling method. The casing structure is determined in the early stage of design, and then appropriate casing material, air temperature, and cooling method are selected to change the response curve of casing deformation, thereby achieving the corresponding blade tip clearance matching purpose. By comparing the overall excess clearance of different schemes, the optimal parameters are selected, and the overall excess clearance optimization effect is finally determined.

[0039] Preferably, in step S600, the initial cold clearance is determined by the minimum allowable working clearance and the optimized narrow point clearance, that is, the narrow point clearance must be greater than the minimum allowable working clearance in any state of the engine.

[0040] Understandably, the initial cold clearance is determined by the minimum permissible working clearance and the optimized narrow point clearance. That is, the narrow point clearance should be greater than the minimum permissible working clearance. This condition must be met under any condition, because the minimum permissible working clearance may be different under different engine conditions. Generally speaking, the minimum permissible working clearance at takeoff is relatively larger than that at cruise.

[0041] It should be noted that a single optimization may not meet all requirements. Steps S500 and S600 are iteratively calculated until the engine design requirements are met.

[0042] In summary, this application relates to a passive turbine tip clearance matching method based on engine requirements; it involves methods for tip clearance matching analysis and optimization; and it includes evaluating tip clearance matching optimization based on the comprehensive excess clearance optimization effect proposed according to engine requirements. The passive turbine tip clearance matching method proposed in this application can analyze turbine tip clearance and optimize clearance matching for different engine requirements. It uses turbine materials and cooling as adjustment means, combined with comprehensive excess clearance and other indicators, to evaluate the optimized turbine tip clearance, achieving better control of turbine tip clearance levels and ultimately improving turbine efficiency, reducing engine fuel consumption, and enhancing performance.

[0043] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0044] It should be understood that in the foregoing description of the embodiments in this specification, various features are combined in a single embodiment, drawing, or description for the purpose of simplifying the description and aiding in the understanding of a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may readily identify some of the devices as separate embodiments when reading this specification. That is, the embodiments in this specification can also be understood as an integration of multiple secondary embodiments. It is also valid when each secondary embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

Claims

1. A passive matching method for turbine blade tip clearance based on engine requirements, characterized in that, Includes the following steps: S100: Determine the minimum permissible working clearance according to engine design requirements; S200: Determine the typical tip clearance analysis load spectrum based on the engine's operating scenario; S300: Thermal and deformation analyses of the rotor and stator are performed through three-dimensional simulation to obtain the radial deformation response curves of the turbine rotor and the stator under typical engine operating load spectra. S400: Based on the deformation results of the rotor and stator, the variation law of the blade tip clearance is analyzed to obtain the variation law of the blade tip clearance; S500: The blade tip clearance is optimized for different engine requirements, taking into account the casing material, structure, and cooling method. S600: The anti-scratch casing deformation curve is obtained by adding the minimum allowable working clearance to the radial deformation response curve of the turbine rotor. The actual deformation curve of the casing is obtained by calculation. The intersection of the actual deformation curve of the casing and the anti-scratch casing deformation curve is the narrow point clearance. The initial cold state clearance is determined according to the narrow point clearance and the minimum allowable working clearance. S700: Iteratively calculate steps S500 and S600 until the blade tip clearance meets the engine design requirements, and determine the final blade tip clearance matching scheme.

2. The passive matching method for turbine tip clearance based on engine requirements according to claim 1, characterized in that, Step S100 specifically includes: determining the corresponding minimum allowable blade tip clearance based on each steady-state operating state of the engine, so that the turbine blade tip operating clearance is not less than the minimum allowable blade tip clearance.

3. The passive matching method for turbine tip clearance based on engine requirements according to claim 2, characterized in that, When determining the minimum permissible working clearance, the effects of at least one of the following factors on rotor and stator deformation should be considered: deflection caused by gravity and gyroscopic torque during maneuvering; ellipticity caused by installation loads; machining errors and eccentricity; bearing radial clearance; rotor imbalance under normal conditions; deformation caused by engine surge; asymmetric thermal and pressure distortion; rotor whirling during hot engine restart; blade twisting and rotor creep elongation.

4. The passive matching method for turbine blade tip clearance based on engine requirements according to claim 1, characterized in that, In step S200, the typical tip clearance analysis load spectrum includes the processes of ground slowdown, takeoff, climb, cruise, descent and re-acceleration.

5. The passive matching method for turbine tip clearance based on engine requirements according to claim 1, characterized in that, Step S300 specifically includes: performing rotor thermal analysis and deformation analysis using the three-dimensional finite element method to obtain the temperature field change of the rotor; combining the condition of engine speed change, performing structural deformation analysis on the rotor to obtain the radial deformation result at the rotor blade tip; performing stator thermal analysis and deformation analysis using the three-dimensional finite element method to obtain the temperature field change of the stator; combining the condition of stator pressure load, performing structural deformation analysis on the stator to obtain the radial deformation result at the outer ring of the stator.

6. The passive matching method for turbine tip clearance based on engine requirements according to claim 5, characterized in that, In step S400, the tip clearance is calculated using the following formula based on the radial deformation results at the rotor blade tip and the stator outer ring. δ hot : ； In the formula, It is the initial cold gap. It is the radial deformation at the outer ring of the stator. It is the radial deformation at the rotor blade tip.

7. The passive matching method for turbine tip clearance based on engine requirements according to claim 1, characterized in that, In step S500, the portion of the actual blade tip clearance that is greater than the minimum allowable working clearance is set as excess clearance. Blade tip clearance matching optimization is performed according to the engine's purpose and requirements. For engines that prioritize fuel efficiency, the blade tip clearance during the cruise phase is matched first, while also taking into account the excess clearance throughout the entire flight cycle. For engines that prioritize maximum power, the blade tip clearance at maximum power is matched first.

8. The passive matching method for turbine tip clearance based on engine requirements according to claim 7, characterized in that, In step S500, after completing the blade tip clearance matching optimization, the overall excess clearance is used to measure the clearance matching situation. The overall excess clearance is the integral of the excess clearance over time. The overall excess clearance of each stage of the engine is weighted and summed to calculate the overall excess clearance optimization effect, and the overall excess clearance optimization effect η is obtained. ； ； In the formula, This refers to the overall excess gap before optimization at each stage. The optimized overall excess gap for each stage, The weighting coefficient for the overall excess clearance at each stage, with the subscript i indicating different engine operating states.

9. The passive matching method for turbine tip clearance based on engine requirements as described in claim 1, characterized in that, In step S500, after determining the weighting coefficient of the overall excess clearance at each stage, the clearance matching of the rotor and stator is achieved by changing the casing material, structure, and cooling method. The casing structure is determined in the early stage of design. Then, appropriate casing material, air temperature, and cooling method are selected to change the response curve of casing deformation, so as to achieve the corresponding blade tip clearance matching purpose. By comparing the overall excess clearance of different schemes, the optimal parameters are selected, and the overall excess clearance optimization effect is finally determined.

10. The passive matching method for turbine tip clearance based on engine requirements according to claim 1, characterized in that, In step S600, the narrow point clearance must be greater than the minimum allowable working clearance in any state of the engine.

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