Air-cooled turbine efficiency correction method considering cold air temperature ratio change

Abstract

The invention discloses an air-cooled turbine efficiency correction method considering cold air temperature ratio change, which comprises the following steps: implementing a reference test with the total temperature ratio of 1 to obtain reference efficiency; an actual low-temperature test with the total temperature ratio being equal is implemented, and efficiency is obtained; a non-isothermal heat transfer entropy production calculation model is constructed, and cold air and mainstream mixing entropy production when the total temperature ratio is YES and cold air and mainstream mixing entropy production when the total temperature ratio is YES under the actual working condition are calculated; and calculating to obtain the correction efficiency when the total temperature ratio of the actual working condition is when. The entropy production theory is innovatively introduced to construct the correction model, and the defects that an existing method is weak in theoretical basis and incomplete in loss consideration are thoroughly overcome; extreme low-temperature test conditions are not needed, the equipment cost and the safety risk are greatly reduced, and the engineering feasibility and economical efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of aerodynamic performance correction technology for air-cooled turbines, and more particularly to a method for correcting the efficiency of air-cooled turbines that takes into account changes in the temperature ratio of the cooling gas. Background Technology

[0002] With the increasing thrust requirements of aero-engines, the inlet temperature of high-pressure turbines exceeds the melting point of the high-temperature alloys used in turbine blades. Turbine blades require various cooling designs, among which a cooling film is a key method, effectively isolating the blades from the high-temperature mainstream. In aero-engine design, turbine aerodynamic performance testing is indispensable for verifying design schemes and evaluating feedback aerodynamic designs; design and testing complement each other. However, the extreme operating environment of high-pressure turbines makes full-temperature, full-pressure testing difficult, costly, and unsafe. Therefore, component testing is often conducted in medium- and low-temperature environments. This results in differences between the test environment and the actual operating environment, affecting the similarity of the turbine flow field and performance.

[0003] To ensure similarity in flow field and performance, similar parameters are selected in experiments. However, for high-pressure gas-cooled turbines, it is difficult to guarantee that the total temperature ratio between the cold gas and the mainstream is consistent, which undermines the similarity and leads to discrepancies between experimental data and actual operating efficiency, reducing the authenticity and reliability of the experimental results. Specifically, for high-pressure gas-cooled turbines, ensuring the specific heat ratio, Re, expansion ratio, equivalent rotational speed, and the total temperature ratio and flow rate ratio (total pressure ratio) between the cold gas and the mainstream can guarantee the similarity between the turbine's performance and flow field under low-temperature tests and actual operating conditions. However, the mainstream of high-pressure gas-cooled turbine tests is already at a low temperature. If the cold gas is to maintain a temperature ratio with the mainstream, it would be at an even lower temperature, making it difficult to achieve a long-term, stable supply of cold gas in actual experiments. Currently, there are two main understandings and solutions in experiments: one is that early studies believed the temperature ratio had a small and negligible impact, but with the increasing requirements for experimental precision, this method lacks theoretical support and has been questioned. Secondly, some studies, starting from the formation mechanism of mixing loss, believe that the momentum ratio of the mainstream and the cold air should be consistent. However, the approach of only ensuring the momentum ratio only considers the momentum exchange loss caused by velocity difference, and does not consider the internal energy exchange loss caused by temperature difference. The consideration of flow field loss is still insufficient.

[0004] In summary, existing technologies for addressing the temperature ratio problem in high-pressure gas-cooled turbine experiments suffer from insufficient theoretical support and difficulty in meeting practical accuracy requirements. Furthermore, they do not comprehensively consider flow field losses, making it difficult to meet the current high demands for the authenticity and reliability of experimental results. Summary of the Invention

[0005] This invention provides a method for correcting the efficiency of an air-cooled turbine that considers changes in the cold gas temperature ratio. This method addresses the technical problem in high-pressure air-cooled turbine tests where the cold gas temperature cannot be reduced to the extremely low level required by similarity criteria, resulting in an inconsistency between the cold gas / mainstream total temperature ratio and the actual operating conditions. This leads to a significant deviation between the test efficiency and the actual performance. Existing methods either completely ignore the influence of the temperature ratio or only consider the similarity of the momentum ratio, thus neglecting the internal energy exchange loss caused by temperature differences. These methods are no longer able to meet the increasingly demanding requirements for test accuracy.

[0006] Methods for correcting the efficiency of air-cooled turbines that take into account changes in the cooling gas temperature ratio include:

[0007] S1. Conduct a baseline test with a total temperature ratio of 1, i.e., a baseline test where the total temperature of the cooled air is equal to the total temperature of the mainstream air, and calculate the baseline efficiency based on the test results. ;

[0008] S2. Based on the actual conditions of the experimental equipment, the minimum total temperature ratio that can be achieved is: Actual low-temperature tests were conducted, and the efficiency under this operating condition was calculated based on the test results. ;

[0009] S3. Construct a non-isothermal heat transfer entropy production calculation model and calculate the total temperature ratio as follows: The cold air and mainstream mixing entropy production The total temperature ratio under actual operating conditions is The cold air and mainstream mixing entropy production ;

[0010] S4. Based on the assumptions of linear entropy production and loss invariance, utilizing benchmark efficiency Total temperature ratio is Time efficiency , and By correcting the formula, the total temperature ratio under actual operating conditions is calculated to be: Time correction efficiency .

[0011] The present invention has the following beneficial effects:

[0012] This invention addresses the performance discrepancy caused by the inconsistency between the cooling gas temperature ratio and the actual operating conditions in high-pressure gas-cooled turbine tests. Based on entropy production theory, a non-isothermal heat transfer entropy production model is constructed, innovatively proposing linear entropy production and loss invariance assumptions to achieve precise correction of test efficiency. Compared to traditional methods (such as ignoring the influence of temperature ratio or only considering momentum ratio similarity), this invention decomposes mixing losses into three components: non-isothermal heat transfer, total pressure loss, and gas composition differences. It systematically solves the fundamental technical problem of inaccurate total temperature ratio and large deviations between test efficiency and actual performance caused by the inability of the cooling gas to reach the extreme low temperatures required by the similarity criterion, from the perspective of the second law of thermodynamics. Numerical simulations have verified that this correction method significantly reduces the deviation between the corrected efficiency and the actual efficiency, overcoming the shortcomings of existing methods that lack comprehensive consideration of loss mechanisms and have poor efficiency evaluation effects. Furthermore, it is applicable to different cooling gas volume conditions and has strong universality.

[0013] In this invention, the total entropy increase is subdivided into three components—non-isothermal heat transfer, total pressure drop, and gas type difference—through a mixed entropy increase decomposition model. Based on the assumptions of linear entropy production and constant loss, an efficiency prediction model based on entropy production is established. Furthermore, this correction method does not require extreme low-temperature test conditions, overcoming the practical limitations of existing technologies. Existing technologies, if forced to meet the temperature ratio similarity criterion, require the development of ultra-low temperature cold gas supply systems, facing multiple obstacles such as high equipment development costs, poor long-term operational reliability, and high test safety risks, making them almost impractical. The "calculation-based" strategy proposed in this invention only requires conducting a normal temperature benchmark test with a total temperature ratio of 1 and a minimum total temperature ratio test within the equipment's capabilities. It can accurately calculate the actual efficiency through theoretical correction without pursuing extreme low-temperature conditions, significantly reducing the threshold for test equipment and operating costs, avoiding the risks of ultra-low temperature technology, and making high-precision data, previously unavailable due to limited conditions, readily available, greatly improving engineering feasibility and economy.

[0014] This invention improves the authenticity and reliability of experimental results, providing more accurate data support for aero-engine turbine design, which helps optimize turbine aerodynamic performance and improve overall engine efficiency. The method is not only applicable to current high-pressure air-cooled turbines but can also be extended to higher-temperature, more advanced turbine designs, driving aero-engine technology towards higher performance and lower cost, and has significant engineering application value and industry-driving effect. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of an air-cooled turbine efficiency correction method considering changes in the cooling gas temperature ratio in one embodiment of the present invention.

[0017] Figure 2 This is a structural diagram of an air-cooled turbine efficiency correction system that considers the impact of the cooling gas temperature ratio on performance in one embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of a single guide vane and moving blade with a cooling turbine in one embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of the location of the cold air duct in one embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram comparing the efficiency deviation before and after correction in one embodiment of the present invention. Detailed Implementation

[0021] 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, not all, of the embodiments of the present invention. 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.

[0022] The air-cooled turbine efficiency correction method considering the change in the air-cooled temperature ratio provided in this embodiment of the invention is applied to an air-cooled turbine efficiency correction system that considers the impact of the air-cooled temperature ratio on performance.

[0023] In one embodiment, such as Figure 1 As shown, a method for correcting the efficiency of an air-cooled turbine considering changes in the cooling gas temperature ratio is provided, including the following steps:

[0024] S1. Conduct a baseline test with a total temperature ratio of 1, i.e., a baseline test where the total temperature of the cooled air is equal to the total temperature of the mainstream air, and calculate the baseline efficiency based on the test results. .

[0025] In one embodiment, step S1 includes the following sub-steps:

[0026] S101. Construct a decomposition model for entropy increase during mixing, representing the total entropy increase of the mixing process between the cooling gas and the mainstream in the air-cooled turbine. It consists of three components: the entropy increase caused by isothermal heat transfer between the cold air and the mainstream gas. The entropy increase caused by the decrease in total pressure due to mixing And the entropy increase caused by the different types of gases in the mainstream air and the cold air. This serves as the theoretical framework for subsequent loss calculations; among which, remember , Recorded as , Recorded as ;

[0027] S102. Set the entropy increase constraint condition for the baseline operating condition, based on the condition that the mainstream and the cold air are the same type of gas working fluid, and let At the same time, assume The mixing loss between the cold air and the mainstream gas is independent of the change in the cold air temperature ratio and its proportion is below the engineering threshold; it is set that when the cold air temperature ratio changes, the mixing loss between the cold air and the mainstream gas is only caused by the entropy increase due to the non-isothermal heat transfer between the cold air and the mainstream gas. leading;

[0028] S103, Settings ,Will Divided into those dominated by temperature difference and pressure differential dominance Efficiency is divided into three components, and the mathematical expression for efficiency is:

[0029] (1).

[0030] S104, Set the total reduced isentropic work The total reduced isentropic work remains constant regardless of the total temperature of the cooling system, even when the total temperature of the cooling system varies with the same amount of cooling. Therefore, the mathematical expression for efficiency is the same for the same amount of cooling. The second item It does not change with the total temperature of the air conditioner; indicating

[0031] S105, Order Calculate the baseline efficiency of the benchmark test with a total temperature ratio of 1. Baseline efficiency The calculation expression is:

[0032] (2)

[0033] in, This represents the losses of both the cool air and the mainstream air during the expansion and work done in the turbine flow channel. This indicates the loss caused by the decrease in total pressure due to the mixing of cold air with the mainstream.

[0034] S2. Based on the actual conditions of the experimental equipment, the minimum total temperature ratio that can be achieved is: Actual low-temperature tests were conducted, and the efficiency under this operating condition was calculated based on the test results. .

[0035] In one embodiment, step S2 includes the following sub-steps:

[0036] S201. Determine the minimum cooling temperature and the adjustment range of the mainstream temperature within which the test equipment can operate stably for a long period of time, and determine the test boundary constraints; calculate the minimum feasible total temperature ratio based on the equipment's ultimate capacity. ;

[0037] S202. Assuming different total temperatures of the cooling air, what are the losses of the cooling air and the mainstream air during the expansion and work done in the turbine flow channel? If the total temperature of the cooling system remains constant, then the mathematical expression for efficiency is as follows: Only the last item When changes occur, the mathematical expression for efficiency can be transformed into:

[0038] (3);

[0039] Among them, let The total temperature ratio is obtained as Time efficiency The ratio of total temperature to Time efficiency They are respectively:

[0040] (4).

[0041] S3. Construct a non-isothermal heat transfer entropy production calculation model and calculate the total temperature ratio as follows: The cold air and mainstream mixing entropy production The total temperature ratio under actual operating conditions is The cold air and mainstream mixing entropy production .

[0042] In one embodiment, step S3 includes the following sub-steps:

[0043] S301. Construct a calculation model for entropy production in isothermal heat transfer. The mathematical expression for the calculation model for entropy production in isothermal heat transfer is:

[0044] (5);

[0045] S302. Based on the mathematical expression of the isothermal heat transfer entropy production calculation model, the total temperature ratio is calculated as follows: The cold air and mainstream mixing entropy production The total temperature ratio under actual operating conditions is The cold air and mainstream mixing entropy production Their mathematical expressions are as follows:

[0046] (6)

[0047] (7).

[0048] S4. Based on the assumptions of linear entropy production and loss invariance, utilizing benchmark efficiency Total temperature ratio is Time efficiency , and By correcting the formula, the total temperature ratio under actual operating conditions is calculated to be: Time correction efficiency .

[0049] In one embodiment, step S4 includes the following sub-steps:

[0050] S401, Setting the total reduced isentropic work Without changing the total temperature of the air conditioner, combined with the baseline efficiency Total temperature ratio is Time efficiency , and By correcting the formula, the total temperature ratio under actual operating conditions is obtained as follows: Time efficiency The expression is:

[0051] (8);

[0052] S402, Settings The total temperature ratio under actual operating conditions was obtained as follows: Time efficiency Efficiency of formal revision for:

[0053] (9).

[0054] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0055] Understandably, the core of the above-mentioned steps of this invention lies in the efficiency correction model formed based on the entropy production formation mechanism and the relationship between entropy production and efficiency, as well as the analysis and assumptions made therein. The core of the efficiency correction model is the assumption that when the temperature ratio between the cold air and the mainstream changes, the entropy increase is mainly caused by the temperature difference change, while other losses remain unchanged. Therefore, when only the temperature ratio between the cold air and the mainstream changes, the turbine efficiency is linearly related to the entropy production caused by the temperature difference. Thus, having obtained the efficiency at a temperature ratio of 1 and the efficiency at any temperature ratio, the efficiency at the desired temperature ratio can be obtained by using the relationship of entropy production.

[0056] In one specific embodiment, a certain type of single-stage high-pressure turbine with cooling air (its structure is as follows) is applied. Figure 3 (As shown) to demonstrate the method of this invention, the numerical simulation software selected is CFX19.0, which is used to solve the three-dimensional steady RANS equations, and the SST model is selected as the turbulence model. The computational domain consists of a single stator channel and a single rotor channel, and the computational domain is extended at the leading edge of the stator blade and the trailing edge of the rotor. FluentMeshing is used for unstructured mesh generation, with the mesh type being a triangular prism boundary layer mesh plus a tetrahedral mesh, with a total of approximately 6.81 million meshes, of which 3.51 million are in the stator channel and 3.3 million are in the rotor channel. The two sides of the computational domain are set as periodic interfaces, and the rotor domain and the stator domain are set as a rotor-stator interface. All walls in the computational domain are adiabatic non-slip walls. The turbine main inlet boundary conditions are set as total temperature and total pressure and set as axial intake. Two methods are selected for the cold air inlet boundary conditions: total temperature and flow rate, and total temperature and total pressure, and the results are compared. The outlet boundary condition is set as outlet static pressure, and the turbulence intensity is set to 5%.

[0057] For this gas-cooled high-pressure turbine, the working fluid in the simulation was set to be the same as that in the prototype turbine, both being gas with an oil-to-air ratio of 0.019. Variable specific heat was calculated by importing the relationship between constant-pressure specific heat capacity and temperature. The inlet was set to axial intake. During the numerical simulation, the cold air inlet adopted a trough-type structure, with a total cold air volume of 11%. The positions of each cold air trough are as follows: Figure 4 As shown in Table 1, the corresponding airflow rates at each location are: 0.04 kg / s, 0.04 kg / s, 0.04 kg / s, 0.03 kg / s, 0.038 kg / s, 0.03 kg / s, 0.03 kg / s, 0.03 kg / s, 0.03 kg / s, and 0.03 kg / s, respectively.

[0058] Table 1

[0059]

[0060] The efficiency with a total inlet temperature of 206.76 K is used as the target to be corrected (i.e. ), using the mainstream temperature of 500K as the calculation example for the air conditioning temperature (i.e. ), using cold air temperatures of 248.12K, 288.15K, and 328.15K as known values ​​(i.e. Each of these is corrected using a correction formula. Figure 5 The results before and after the efficiency correction formula are shown to differ from the efficiency calculated using numerical simulation at a total inlet temperature of 206.76 K. After correction using this method, the deviation from the actual efficiency is greatly reduced.

[0061] Specifically, Table 2 shows the efficiency and corrected efficiency at various total air temperatures under a 14% air volume: when the total air temperature is 248.12K, 288.15K, and 328.15K, the corrected efficiencies are 87.67%, 87.74%, and 87.79%, respectively. Table 3 shows the efficiency and corrected efficiency at various total air temperatures under an 18% air volume: when the total air temperature is 248.12K, 288.15K, and 328.15K, the corrected efficiencies are 87.12%, 87.27%, and 87.32%, respectively. The overall results show that under both air volume conditions, the efficiency deviation is significantly reduced after applying the correction method of this invention, verifying the effectiveness and universality of the method.

[0062] Table 2

[0063]

[0064] Table 3

[0065]

[0066] In one embodiment, an air-cooled turbine efficiency correction system that considers the impact of the air-cooled temperature ratio on performance is provided. This system corresponds one-to-one with the air-cooled turbine efficiency correction method that considers changes in the air-cooled temperature ratio in the above embodiments. Figure 2 As shown, the air-cooled turbine efficiency correction system that considers the impact of the cooling gas temperature ratio on performance includes:

[0067] The baseline efficiency calculation module is used to conduct a baseline test with a total temperature ratio of 1, i.e., a baseline test where the total temperature of the cooled air is equal to the total temperature of the mainstream air, and calculates the baseline efficiency based on the test results. ;

[0068] The operating condition efficiency calculation module is used to calculate the minimum achievable total temperature ratio based on the actual conditions of the test equipment. Actual low-temperature tests were conducted, and the efficiency under this operating condition was calculated based on the test results. ;

[0069] The entropy production calculation module is used to construct an entropy production calculation model for non-isothermal heat transfer, and to calculate the total temperature ratio as follows: The cold air and mainstream mixing entropy production The total temperature ratio under actual operating conditions is The cold air and mainstream mixing entropy production ;

[0070] The modified efficiency calculation module is used to calculate the baseline efficiency based on the linear entropy production assumption and the loss invariance assumption. Total temperature ratio is Time efficiency , and By correcting the formula, the total temperature ratio under actual operating conditions is calculated to be: Time correction efficiency .

[0071] Specific limitations regarding the performance correction system for air-cooled turbines that consider the impact of air-cooled temperature ratio on performance can be found in the limitations of the air-cooled turbine efficiency correction method considering changes in air-cooled temperature ratio described above, and will not be repeated here. Each module in the aforementioned air-cooled turbine efficiency correction system that considers the performance impact of air-cooled temperature ratio can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0072] In one embodiment, a computer device, which may be a server, is provided. The computer device includes a processor, memory, a network interface, and a database connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database is used for air-cooled turbine efficiency correction considering the performance impact of air-cooled temperature ratio. The network interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements an air-cooled turbine efficiency correction method considering changes in air-cooled temperature ratio.

[0073] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the air-cooled turbine efficiency correction method considering changes in the air-cooled temperature ratio described in the above embodiment. To avoid repetition, this will not be repeated here. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the air-cooled turbine efficiency correction system considering the performance impact of the air-cooled temperature ratio in this embodiment. To avoid repetition, this will not be repeated here.

[0074] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When executed by a processor, the computer program implements the air-cooled turbine efficiency correction method considering changes in the air-cooled gas temperature ratio described in the above embodiment. To avoid repetition, this will not be described again here. Alternatively, when executed by a processor, the computer program implements the functions of each module / unit in the air-cooled turbine efficiency correction system considering the performance impact of the air-cooled gas temperature ratio described in the above embodiment. To avoid repetition, this will not be described again here.

[0075] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0076] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above.

[0077] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for correcting the efficiency of an air-cooled turbine considering changes in the cooling gas temperature ratio, characterized in that, include: S1. Conduct a baseline test with a total temperature ratio of 1, i.e., a baseline test where the total temperature of the cooled air is equal to the total temperature of the mainstream air, and calculate the baseline efficiency based on the test results. ; S2. Based on the actual conditions of the experimental equipment, the minimum total temperature ratio that can be achieved is: Actual low-temperature tests were conducted, and the efficiency under this operating condition was calculated based on the test results. ; S3. Construct a non-isothermal heat transfer entropy production calculation model and calculate the total temperature ratio as follows: The cold air and mainstream mixing entropy production The total temperature ratio under actual operating conditions is The cold air and mainstream mixing entropy production ; S4. Based on the assumptions of linear entropy production and loss invariance, utilizing benchmark efficiency Total temperature ratio is Time efficiency , and By correcting the formula, the total temperature ratio under actual operating conditions is calculated to be: Time correction efficiency .

2. The method for correcting the efficiency of an air-cooled turbine considering changes in the cooling gas temperature ratio according to claim 1, characterized in that, Step S1 further includes the following sub-steps: S101. Construct a decomposition model for entropy increase during mixing, representing the total entropy increase of the mixing process between the cooling gas and the mainstream in the air-cooled turbine. It consists of three components: the entropy increase caused by isothermal heat transfer between the cold air and the mainstream gas. The entropy increase caused by the decrease in total pressure due to mixing And the entropy increase caused by the different types of gases in the mainstream air and the cold air. This serves as the theoretical framework for subsequent loss calculations; among which, remember , Recorded as , Recorded as ; S102. Set the entropy increase constraint condition for the baseline operating condition, based on the condition that the mainstream and the cold air are the same type of gas working fluid, and let At the same time, assume The mixing loss between the cold air and the mainstream gas is independent of the change in the cold air temperature ratio and its proportion is below the engineering threshold; it is set that when the cold air temperature ratio changes, the mixing loss between the cold air and the mainstream gas is only caused by the entropy increase due to the non-isothermal heat transfer between the cold air and the mainstream gas. leading; S103, Settings ,Will Divided into those dominated by temperature difference and pressure differential dominance Efficiency is divided into three components, and the mathematical expression for efficiency is: （1）； S104, Set the total reduced isentropic work The total reduced isentropic work remains constant regardless of the total temperature of the air conditioning unit, even when the total temperature of the air conditioning unit varies with the same amount of air conditioning. Therefore, the second term in the mathematical expression for efficiency remains constant for the same amount of air conditioning. It does not change with the overall temperature of the air conditioner; S105, Order Calculate the baseline efficiency of the benchmark test with a total temperature ratio of 1. Baseline efficiency The calculation expression is: （2） in, This represents the losses of both the cool air and the mainstream air during the expansion and work done in the turbine flow channel. This indicates the loss caused by the decrease in total pressure due to the mixing of cold air with the mainstream.

3. The method for correcting the efficiency of an air-cooled turbine considering changes in the cooling gas temperature ratio according to claim 2, characterized in that, Step S2 further includes the following sub-steps: S201. Determine the minimum cooling temperature and the adjustment range of the mainstream temperature within which the test equipment can operate stably for a long period of time, and determine the test boundary constraints; calculate the minimum feasible total temperature ratio based on the equipment's ultimate capacity. ; S202. Assuming different total temperatures of the cooling air, what are the losses of the cooling air and the mainstream air during the expansion and work done in the turbine flow channel? If the total temperature of the cooling system remains constant, then when the total temperature of the cooling system changes, the mathematical expression for efficiency will only have the last term. When changes occur, the mathematical expression for efficiency can be transformed into: （3）； Among them, let The total temperature ratio is obtained as Time efficiency The ratio of total temperature to Time efficiency They are respectively: （4）。 4. The method for correcting the efficiency of an air-cooled turbine considering changes in the cooling gas temperature ratio according to claim 3, characterized in that, Step S3 further includes the following sub-steps: S301. Construct a calculation model for entropy production in isothermal heat transfer. The mathematical expression for the calculation model for entropy production in isothermal heat transfer is: （5）； S302. Based on the mathematical expression of the isothermal heat transfer entropy production calculation model, the total temperature ratio is calculated as follows: The cold air and mainstream mixing entropy production The total temperature ratio under actual operating conditions is The cold air and mainstream mixing entropy production Their mathematical expressions are as follows: （6） （7）。 5. The method for correcting the efficiency of an air-cooled turbine considering changes in the cooling gas temperature ratio according to claim 4, characterized in that, Step S4 further includes the following sub-steps: S401, Setting the total reduced isentropic work Without changing the total temperature of the air conditioner, combined with the baseline efficiency Total temperature ratio is Time efficiency , and By correcting the formula, the total temperature ratio under actual operating conditions is obtained as follows: Time efficiency The expression is: （8）； S402, Settings The total temperature ratio under actual operating conditions was obtained as follows: Time efficiency Efficiency of formal revision for: （9）。

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