Combination selection method of ejector for regulating and controlling temperature of turbine casing

Abstract

The invention discloses an ejector combination selection method for regulating and controlling the temperature of a turbine casing, and the method comprises the steps: carrying out the iterative calculation according to the metal temperature requirement of the turbine casing, and finally selecting an ejector combination with the minimum ejection flow to achieve the mixing and diffusion of the injected gas. Compared with the prior art, the air entraining amount of an air system is reduced to the maximum extent, the performance of an aero-engine is improved, the oil consumption rate of the aero-engine is reduced, in addition, the metal temperature of the turbine case can be actively regulated and controlled by actively selecting the ejector combination, and the service life of the turbine case is prolonged. And the method is high in practicability and suitable for being widely popularized and applied.

Description

Technical Field

[0001] The present invention relates to the technical field of aeroengines, and in particular to an ejector combination selection method for regulating turbine casing temperature. Background Art

[0002] The air system is the secondary flow system of the aircraft engine, which is mainly used to ensure that the engine can maintain efficient and stable operation under various working conditions. The increase of the air intake volume of the air system will lead to reduced engine thrust, increased exhaust temperature, increased fuel consumption, increased oil-gas ratio, reduced total pressure at the high-pressure compressor outlet, and increased kick margin of the high-pressure compressor. This is because the air intake of the air system mainly comes from the compressed gas in the compressor, and the compressed gas drawn out from the compressor should enter the combustion chamber to mix with the fuel and burn, and participate in the thermal cycle of the engine and do external work as the mainstream, but it is drawn out to meet the functional requirements of the air system, thus losing the opportunity to do work, resulting in a decrease in engine performance. Therefore, under the condition of meeting reliability and safety performance, the aircraft engine will minimize the amount of air intake of the air system to reduce the impact on engine performance and reduce the engine fuel consumption rate.

[0003] An ejector is a device that uses a high-speed fluid to eject another low-speed fluid. Its working principle is to transfer energy to the ejected fluid through the expansion of the high-speed fluid in the contraction-shaped nozzle, so that the two are mixed in the mixing chamber, thereby increasing the pressure and speed of the ejected fluid. Therefore, the ejector can be applied to the air system of an aircraft engine by ejecting a large amount of low-pressure gas after a small amount of high-pressure gas flows through the Rafale nozzle, thereby doubling the flow rate and reducing the temperature of the ejected gas. For example, Chinese invention patent application CN115788601A discloses an ejector air bleed device for controlling the clearance of the turbine blade tip of an aircraft engine, specifically an ejector air bleed device for controlling the clearance of the turbine blade tip of an aircraft engine, wherein two ejectors are arranged circumferentially of the engine, and two bleed air pipelines and an exhaust pipeline are installed on each ejector; a partition is installed between the turbine casing and the combustion chamber casing to form an annular chamber; and the two gases sucked in by the two bleed air pipelines are mixed and expanded by the ejector, and the outlet fluid is discharged. The present invention can ensure that the circumferential temperature of the air flow in the annular chamber that provides the air source for cooling the turbine casing is uniform by combining two ejectors. At the same time, the ejector structure dimensions are optimized so that the ejection coefficient of the ejector reaches 1.7 and the expansion ratio of the ejected fluid reaches 1.4, thereby meeting the cooling requirements of the tip clearance control of the high-pressure turbine casing of small and medium-sized aircraft engines with high compression ratios.

[0004] However, although the above-mentioned induced air bleed device can control the turbine casing tip clearance by regulating the temperature of the turbine casing, it cannot ensure that the induced air flow of the induced air bleed device is minimum. Therefore, the bleed air volume of the air system is still relatively large, the performance of the aircraft engine is poor, and the fuel consumption rate is high. Summary of the invention

[0005] The present invention provides an ejector combination selection method for regulating turbine casing temperature, so as to solve the technical problems that the air system of the existing aircraft engine has a relatively large amount of bleed air, the performance of the aircraft engine is poor, and the fuel consumption rate is high.

[0006] According to one aspect of the present invention, there is provided a method for selecting an ejector combination for regulating the temperature of a turbine casing, characterized in that it comprises the following steps: S1, obtaining the gas side temperature and the gas side heat transfer coefficient of the turbine casing according to the metal temperature requirement of the turbine casing and the main state parameters in the engine envelope; S2, obtaining the correlation formula between the cold air temperature and the cold air side heat transfer coefficient of the turbine casing according to the gas side temperature and the gas side heat transfer coefficient of the turbine casing and based on the thermodynamic energy balance formula; S3, within the range of aircraft engine parameters, obtaining a solution set of the cold air temperature and the cold air side heat transfer coefficient of multiple groups of turbine casings according to the correlation formula of the cold air temperature and the cold air side heat transfer coefficient of the turbine casing, obtaining a solution set of the cold air temperature and the cold air mass flow rate according to the maximum and minimum values ​​in the solution set of the cold air temperature and the cold air side heat transfer coefficient of the multiple groups of turbine casings and based on the correlation formula of the cold air side heat transfer coefficient and the cold air mass flow rate, and then The solution set is iteratively calculated with the engine overall distribution index and the heat transfer coefficient requirement to discard the solution set that does not meet the requirements of the cooling air temperature and the cooling air mass flow rate, and obtain the solution set of the cooling air temperature and the cooling air mass flow rate that meet the requirements; S4, based on the calculation formula of the ejector parameters, the association formula between the ejector combination and multiple ejectors is obtained to carry out the calculation of the ejector combination parameters to obtain the solution set of the ejector combination parameters and multiple ejector parameters, and based on the association formula of the cooling air temperature and the ejector combination parameters, the solution set of the cooling air temperature and the ejector combination parameters is obtained, and then based on the association formula of the cooling air mass flow rate and the ejector combination parameters, the solution set of the cooling air mass flow rate and the ejector combination parameters is obtained; S5, the ejector combination with the smallest ejection flow rate is selected from the solution set of the cooling air temperature and the cooling air mass flow rate, the solution set of the cooling air temperature and the ejector combination parameters, and the solution set of the cooling air mass flow rate and the ejector combination parameters, and the selection of the ejector combination is realized through the electronic control system.

[0007] Furthermore, in step S2, the correlation formula between the cooling air temperature of the turbine casing and the cooling air side heat transfer coefficient is:

[0008]

[0009] Where A is the heat exchange area, Hwg is the heat transfer coefficient of the gas side of the turbine casing, T g is the gas side temperature of the turbine casing, T w1 is the metal temperature requirement of the turbine casing, λ is the metal thermal conductivity of the turbine casing, δ is the thickness of the turbine casing, T w2 is the cold air side temperature of the turbine case, H wc is the heat transfer coefficient of the cold air side of the turbine casing, T c The air conditioning temperature.

[0010] Furthermore, in step S3, the correlation formula between the heat exchange coefficient on the cold air side and the cold air mass flow rate is:

[0011]

[0012] R e ∞N u ;

[0013]

[0014] Among them, R e is the cooling air Reynolds number, G is the cooling air flow rate, L is the characteristic size of the cooling air side heat exchange, μ is the viscosity coefficient, A2 is the cooling air side flow area, N u is the cold air Nusselt number and λ2 is the cold air thermal conductivity.

[0015] Furthermore, in step S4, the calculation formula of the ejector parameters is:

[0016]

[0017] Where α is the ejector area ratio, A p is the ejector nozzle exit area, A S is the ejector nozzle outlet ejection area, k is the ejector ejection coefficient, G s is the ejected flow rate, G p is the ejector flow rate, c is the ejector specific heat ratio, C ps is the specific heat of the ejected gas at constant pressure, C pp is the specific heat of the constant pressure ejector gas, θ is the total temperature ratio of the ejector, T os is the induced temperature, T op is the ejection gas temperature.

[0018] Furthermore, the ejector combination includes a plurality of ejectors with different ejection coefficients, and the ejectors are connected via a parallel circuit.

[0019] Furthermore, in the ejector combination, the number of ejectors with different ejection coefficients is n1, n2, ... n n .

[0020] Furthermore, in step S4, the correlation formula between the ejector combination and the multiple ejectors is:

[0021] In the ejector combination, the number of ejectors with different ejection coefficients is n1, n2, ... n n ;

[0022]

[0023] Among them, α 总 is the ejector combined area ratio, k 总 is the ejector combination ejection coefficient, c 总 is the ejector combination specific heat ratio, θ 总 is the total temperature ratio of the ejector combination.

[0024] Furthermore, in step S4, the correlation formula between the cold air temperature and the ejector combination parameter is:

[0025]

[0026] Furthermore, in step S4, the correlation formula between the mass flow rate of cold air and the ejector combination parameter is:

[0027] G=(n1C ps1 +n2C ps2 +……n n C psn )+(n1C pp1 +n2C pp2 +……n n C ppn ).

[0028] Furthermore, in step S1, the main state parameters within the engine envelope include engine inlet flow, aerodynamic pressures at various levels of the compressor, temperatures at various levels of the compressor, combustion chamber outlet temperature, temperatures at various levels of the gas turbine, pressures at various levels of the gas turbine, temperatures at various levels of the power turbine, pressures at various levels of the power turbine and engine speed.

[0029] The present invention has the following beneficial effects:

[0030] The method for selecting an ejector combination for regulating the temperature of a turbine casing of the present invention first obtains the gas side temperature and the gas side heat transfer coefficient of the turbine casing according to the metal temperature requirement of the turbine casing and the main state parameters in the engine envelope; then, according to the gas side temperature and the gas side heat transfer coefficient of the turbine casing and based on the thermodynamic energy balance formula, obtains the correlation formula between the cold air temperature and the cold air side heat transfer coefficient of the turbine casing; then, within the aircraft engine parameter range, obtains the solution set of multiple groups of the cold air temperature and the cold air side heat transfer coefficient of the turbine casing through the correlation formula between the cold air temperature and the cold air side heat transfer coefficient of the turbine casing, According to the maximum and minimum values ​​in the solution sets of the cooling air temperature and the cooling air side heat transfer coefficient of multiple groups of turbine casings, and based on the correlation formula between the cooling air side heat transfer coefficient and the cooling air mass flow rate, the solution set of the cooling air temperature and the cooling air mass flow rate is obtained, and the solution set of the cooling air temperature and the cooling air mass flow rate is iteratively calculated with the overall engine allocation index and the heat transfer coefficient requirement to discard the solution set of the cooling air temperature and the cooling air mass flow rate that does not meet the requirements, and obtain the solution set of the cooling air temperature and the cooling air mass flow rate that meets the requirements; then, based on the calculation formula of the ejector parameters, the correlation formula between the ejector combination and multiple ejectors is obtained to carry out ejection. The ejector combination parameters are calculated to obtain the solution set of the ejector combination parameters and multiple ejector parameters, and based on the correlation formula between the cold air temperature and the ejector combination parameters, the solution set of the cold air temperature and the ejector combination parameters is obtained, and then based on the correlation formula between the cold air mass flow rate and the ejector combination parameters, the solution set of the cold air mass flow rate and the ejector combination parameters is obtained; finally, the ejector combination with the smallest ejector flow rate is selected from the solution set of the cold air temperature and the cold air mass flow rate, the solution set of the cold air temperature and the ejector combination parameters, and the solution set of the cold air mass flow rate and the ejector combination parameters, and the ejector combination parameters are realized through an electronic control system. Selection of combination: This scheme performs iterative calculations based on the metal temperature requirement of the turbine casing, and ultimately selects the ejector combination with the smallest ejector flow rate to achieve mixing and diffusing of the ejector gas, thereby meeting the metal temperature requirement of the turbine casing with the smallest ejector flow rate. Compared with the existing technology, this scheme minimizes the amount of air bleed in the air system, improves the performance of the aircraft engine, and reduces the fuel consumption of the aircraft engine. In addition, the metal temperature of the turbine casing can be actively regulated by actively selecting the ejector combination to ensure that the aircraft engine is in the best working condition. This scheme has strong practicality and is suitable for wide promotion and application.

[0031] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 It is a flowchart of the steps of the method for selecting an ejector combination for regulating the temperature of a turbine casing according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0035] like Figure 1 As shown, the method for selecting an ejector combination for regulating the temperature of a turbine casing of the present embodiment is characterized in that it includes the following steps: S1, obtaining the gas side temperature and the gas side heat transfer coefficient of the turbine casing according to the metal temperature requirement of the turbine casing and the main state parameters in the engine envelope; S2, obtaining the correlation formula of the cold air temperature and the cold air side heat transfer coefficient of the turbine casing according to the gas side temperature and the gas side heat transfer coefficient of the turbine casing and based on the thermodynamic energy balance formula; S3, within the range of aircraft engine parameters, obtaining a solution set of the cold air temperature and the cold air side heat transfer coefficient of multiple groups of turbine casings through the correlation formula of the cold air temperature and the cold air side heat transfer coefficient of the turbine casing, obtaining a solution set of the cold air temperature and the cold air mass flow rate according to the maximum and minimum values ​​in the solution sets of the cold air temperature and the cold air side heat transfer coefficient of multiple groups of turbine casings and based on the correlation formula of the cold air side heat transfer coefficient and the cold air mass flow rate, and then comparing the solution set of the cold air temperature and the cold air mass flow rate with the solution set of the cold air temperature and the cold air mass flow rate The overall distribution index of the engine and the heat transfer coefficient requirements are iteratively calculated to discard the solution set that does not meet the requirements of the cooling air temperature and the cooling air mass flow rate, and obtain the solution set of the cooling air temperature and the cooling air mass flow rate that meet the requirements; S4, based on the calculation formula of the ejector parameters, the association formula between the ejector combination and multiple ejectors is obtained to carry out the calculation of the ejector combination parameters to obtain the solution set of the ejector combination parameters and multiple ejector parameters, and based on the association formula of the cooling air temperature and the ejector combination parameters, the solution set of the cooling air temperature and the ejector combination parameters is obtained, and then based on the association formula of the cooling air mass flow rate and the ejector combination parameters, the solution set of the cooling air mass flow rate and the ejector combination parameters is obtained; S5, the ejector combination with the smallest ejection flow rate is selected from the solution set of the cooling air temperature and the cooling air mass flow rate, the solution set of the cooling air temperature and the ejector combination parameters, and the solution set of the cooling air mass flow rate and the ejector combination parameters, and the selection of the ejector combination is realized through the electronic control system. This scheme performs iterative calculations based on the metal temperature requirement of the turbine casing, and ultimately selects the ejector combination with the smallest ejector flow rate to achieve mixing and diffusing of the ejected gas, thereby meeting the metal temperature requirement of the turbine casing with the smallest ejector flow rate. Compared with the existing technology, this scheme minimizes the amount of air bleed in the air system, improves the performance of the aircraft engine, and reduces the fuel consumption rate of the aircraft engine. In addition, the metal temperature of the turbine casing can be actively regulated by actively selecting the ejector combination to ensure that the aircraft engine is in the best working condition. This scheme has strong practicality and is suitable for wide promotion and application.

[0036] It should be understood that, in the air system of an aircraft engine that does not use an ejector, the air system draws air from the compressor and delivers it to the turbine casing through an external pipeline to cool the turbine casing, thereby controlling the temperature. In this embodiment, the air system also draws air from the compressor and enters the ejector through a portion of the air system's external pipeline. The ejector cools the turbine casing by ejecting the low-temperature and low-pressure gas in the nacelle, and actively controls the metal temperature of the turbine casing by iterating with the metal temperature of the turbine casing.

[0037] It should be understood that the amount of bleed air in the air system will directly affect the performance and fuel consumption of the aircraft engine. The demand for high-performance aircraft engines is to minimize the amount of bleed air. This embodiment can take into account both small bleed air volume and high-efficiency cooling, and can also control the metal temperature of the turbine casing by selecting an ejector combination.

[0038] It should be understood that the overall engine distribution index and heat transfer coefficient requirements are known parameters in the iterative calculation process.

[0039] It should be understood that by actively regulating the metal temperature of the turbine casing, the turbine tip clearance can be controlled, thereby adjusting the performance of the aircraft engine.

[0040] In this embodiment, in step S2, the correlation formula between the cooling air temperature of the turbine casing and the cooling air side heat transfer coefficient is:

[0041]

[0042] Where A is the heat exchange area, H wg is the heat transfer coefficient of the gas side of the turbine casing, T g is the gas side temperature of the turbine casing, T w1 is the metal temperature requirement of the turbine casing, λ is the metal thermal conductivity of the turbine casing, δ is the thickness of the turbine casing, T w2 is the cold air side temperature of the turbine case, H wc is the heat transfer coefficient of the cold air side of the turbine casing, T c The air conditioning temperature.

[0043] It should be understood that in the above parameters, T c and T c is an unknown quantity, and the others are known quantities. Therefore, the cold air temperature and the heat transfer coefficient on the cold air side can be obtained through the above-mentioned associated formula and known quantities, providing data support for the subsequent iterative calculation of the cold air mass flow rate.

[0044] In this embodiment, in step S3, the correlation formula between the cold air side heat exchange coefficient and the cold air mass flow rate is:

[0045]

[0046] R e ∞N u ;

[0047]

[0048] Among them, R e is the cooling air Reynolds number, G is the cooling air flow rate, L is the characteristic size of the cooling air side heat exchange, μ is the viscosity coefficient, A2 is the cooling air side flow area, N u is the cold air Nusselt number and λ2 is the cold air thermal conductivity.

[0049] Specifically, since the heat exchange coefficient on the cold air side and the cold air temperature are correlated with each other, the solution set of the cold air temperature and the cold air mass flow rate can be obtained through the above correlation formula.

[0050] It should be understood that, in the above correlation formula, G is an unknown quantity, and the other parameters are known quantities.

[0051] In this embodiment, in step S4, the calculation formula of the ejector parameters is:

[0052]

[0053] Where α is the ejector area ratio, A p is the ejector nozzle exit area, A S is the ejector nozzle outlet ejection area, k is the ejector ejection coefficient, G s is the ejected flow rate, G p is the ejector flow rate, c is the ejector specific heat ratio, C ps is the specific heat of the ejected gas at constant pressure, C pp is the specific heat of the constant pressure ejector gas, θ is the total temperature ratio of the ejector, T os is the induced temperature, T op is the ejection gas temperature.

[0054] In this embodiment, the ejector assembly includes a plurality of ejectors with different ejection coefficients, and the ejectors are connected through a parallel circuit. Specifically, the ejector assembly is formed by connecting a plurality of ejectors with different ejection coefficients in parallel, and different ejector combinations can be selected through the electronic control system, thereby actively regulating the metal temperature of the turbine casing.

[0055] In this embodiment, in the ejector combination, the number of ejectors with different ejection coefficients is n1, n2, ... n n .

[0056] In this embodiment, in step S4, the correlation formula between the ejector combination and the multiple ejectors is:

[0057]

[0058] Among them, α 总 is the ejector combined area ratio, k 总 is the ejector combination ejection coefficient, c 总 is the ejector combination specific heat ratio, θ 总 is the total temperature ratio of the ejector combination.

[0059] Specifically, it can be seen from the above-mentioned correlation formula that by selecting the number of ejectors with different ejection coefficients through the electronic control system, different ejector combinations can be formed, thereby realizing active control of the metal temperature of the turbine casing.

[0060] In this embodiment, in step S4, the correlation formula between the cold air temperature and the ejector combination parameter is:

[0061]

[0062] In this embodiment, in step S4, the correlation formula between the mass flow rate of cold air and the combined parameters of the ejector is:

[0063] G=(n1C ps1 +n2C ps2 +……n n C psn )+(n1C pp1 +n2C pp2 +……n n C ppn ).

[0064] In this embodiment, in step S1, the main state parameters in the engine envelope include engine inlet flow, pneumatic pressures at various levels of compressor, temperatures at various levels of compressor, combustion chamber outlet temperature, temperatures at various levels of gas turbine, pressures at various levels of gas turbine, temperatures at various levels of power turbine, pressures at various levels of power turbine and engine speed.

[0065] The method for selecting the ejector combination for regulating the temperature of the turbine casing of this embodiment has been studied through numerical simulation, and can reduce the air intake volume of the air system by 70%, improve the cooling effect by 40%, and realize active regulation of the metal temperature of the turbine casing by selecting the ejector combination through the electronic control system, with a temperature control range of 200K.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for selecting an ejector combination for regulating turbine casing temperature, characterized in that: The following steps are involved: S1, according to the metal temperature requirement of the turbine casing and the main state parameters in the engine envelope, the gas side temperature and the gas side heat transfer coefficient of the turbine casing are obtained; S2, according to the gas side temperature and the gas side heat transfer coefficient of the turbine casing, and based on the thermodynamic energy balance formula, obtain a correlation formula between the cold air temperature and the cold air side heat transfer coefficient of the turbine casing; S3, within the range of aircraft engine parameters, obtain a solution set of multiple groups of turbine casing cooling air temperature and cooling air side heat transfer coefficient through the correlation formula of the cooling air temperature of the turbine casing and the cooling air side heat transfer coefficient, obtain a solution set of cooling air temperature and cooling air mass flow according to the maximum and minimum values ​​in the solution set of multiple groups of turbine casing cooling air temperature and cooling air side heat transfer coefficient, and based on the correlation formula of cooling air side heat transfer coefficient and cooling air mass flow, and then iteratively calculate the solution set of cooling air temperature and cooling air mass flow with the overall engine allocation index and heat transfer coefficient requirements, so as to discard the solution set of cooling air temperature and cooling air mass flow that do not meet the requirements, and obtain the solution set of cooling air temperature and cooling air mass flow that meet the requirements; S4, based on the calculation formula of the ejector parameters, obtain the correlation formula between the ejector combination and the multiple ejectors, so as to carry out the calculation of the ejector combination parameters, so as to obtain the solution set of the ejector combination parameters and the multiple ejector parameters, and based on the correlation formula between the cold air temperature and the ejector combination parameters, obtain the solution set of the cold air temperature and the ejector combination parameters, and then based on the correlation formula between the cold air mass flow rate and the ejector combination parameters, obtain the solution set of the cold air mass flow rate and the ejector combination parameters; S5, select the ejector combination with the smallest ejector flow rate from the solution set of cold air temperature and cold air mass flow rate, the solution set of cold air temperature and ejector combination parameters, and the solution set of cold air mass flow rate and ejector combination parameters, and realize the selection of the ejector combination through the electronic control system.

2. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 1, characterized in that: In step S2, the correlation formula between the cooling air temperature of the turbine casing and the cooling air side heat transfer coefficient is: Where A is the heat exchange area, H wg is the heat transfer coefficient of the gas side of the turbine casing, T g is the gas side temperature of the turbine casing, T w1 is the metal temperature requirement of the turbine casing, λ is the metal thermal conductivity of the turbine casing, δ is the thickness of the turbine casing, T w2 is the cold air side temperature of the turbine case, H wc is the heat transfer coefficient of the cold air side of the turbine casing, T c The air conditioning temperature.

3. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 1, characterized in that: In step S3, the correlation formula between the heat exchange coefficient on the cold air side and the cold air mass flow rate is: Among them, R e is the cooling air Reynolds number, G is the cooling air flow rate, L is the characteristic size of the cooling air side heat exchange, μ is the viscosity coefficient, A2 is the cooling air side flow area, N u is the cold air Nusselt number and λ2 is the cold air thermal conductivity.

4. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to any one of claims 1 to 3, characterized in that: In step S4, the calculation formula of the ejector parameters is: Where α is the ejector area ratio, A p is the ejector nozzle exit area, A S is the ejector nozzle outlet ejection area, k is the ejector ejection coefficient, G s is the ejected flow rate, G p is the ejector flow rate, c is the ejector specific heat ratio, C ps is the specific heat of the ejected gas at constant pressure, C pp is the specific heat of the constant pressure ejector gas, θ is the total temperature ratio of the ejector, T os is the induced temperature, T op is the ejection gas temperature.

5. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 4, characterized in that: In step S4, the ejector combination includes a plurality of ejectors with different ejection coefficients, and the ejectors are connected via a parallel circuit.

6. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 5, characterized in that: In the ejector combination, the number of ejectors with different ejection coefficients is n1, n2, ... n n .

7. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 6, characterized in that: In step S4, the correlation formula between the ejector combination and the multiple ejectors is: Among them, α 总 is the ejector combined area ratio, k 总 is the ejector combination ejection coefficient, c 总 is the ejector combination specific heat ratio, θ 总 is the total temperature ratio of the ejector combination.

8. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 7, characterized in that: In step S4, the correlation formula between the cold air temperature and the ejector combination parameter is:

9. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to claim 7, characterized in that: In step S4, the correlation formula between the mass flow rate of cold air and the combined parameters of the ejector is: G=(n1C ps1 +n2C ps2 +……n n C psn )+(n1C pp1 +n2C pp2 +……n n C ppn )。 10. The method for selecting an ejector combination for controlling the temperature of a turbine casing according to any one of claims 1 to 3, characterized in that: In step S1, the main state parameters in the engine envelope include engine inlet flow, compressor aerodynamic pressure at each stage, compressor temperature at each stage, combustion chamber outlet temperature, gas turbine temperature at each stage, gas turbine pressure at each stage, power turbine temperature at each stage, power turbine pressure at each stage and engine speed.

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