Redline state test method, test system, computer readable medium, and computer program product for turbofan engine

Abstract

The present application relates to a redline state test method, test system, computer-readable medium, and computer program product for a turbofan engine. The redline state test method includes the following steps: respectively obtaining the first thrust of the engine corresponding to the redline gas temperature of the turbofan engine, the second thrust of the engine corresponding to the redline high-pressure rotor speed, and the third thrust of the engine corresponding to the redline low-pressure rotor speed, and taking the maximum value of the first thrust, the second thrust, and the third thrust as the maximum thrust of the engine; according to the test requirements and the engine bearing strength margin, obtaining the target test thrust corresponding to the engine, and defining the thrust correction coefficient = engine maximum thrust / target test thrust; according to the thrust correction coefficient, determining the total pressure loss coefficient of the turbofan engine inlet.

Description

Technical Field

[0001] The present application relates to a redline state test method, a test system, a computer-readable medium, and a computer program product of a turbofan engine. Background Art

[0002] In the airworthiness test of aircraft engines, high-operating tests such as endurance tests and over-temperature tests require that the two red line states of gas temperature and rotor speed or the three red line states of thrust, gas temperature, and rotor speed be reached at the same time to verify that the engine can operate safely under the expected high operating conditions and that the parts are not damaged beyond the limit. In the actual implementation of the engine red line operating condition test, the test engine with good performance usually has a high temperature margin and rotor speed margin when reaching the rated thrust. By pushing the throttle lever to directly increase the gas temperature and rotor speed to the red line value, the engine thrust will greatly exceed the rated value, and it is also easy to cause the aerodynamic load of the flow channel rotor parts, the fan thrust bearing load, etc. to exceed the limit, resulting in test risks.

[0003] In order to meet the requirements of red line operating condition tests such as endurance tests and over-temperature tests, an adjustment method is urgently needed so that the engine used for airworthiness tests can achieve the red line of high and low pressure rotor speeds and gas temperature of the engine, and the thrust does not exceed the rated value too much, so as to ensure that the parameters affecting the strength and life of key components such as fan thrust bearing load, compressor outlet total pressure, and high pressure rotor axial force are not exceeded. Summary of the invention

[0004] In view of the problems existing in the background technology, the purpose of this application is to provide a redline state test method, test system, computer readable medium, and computer program product for a turbofan engine. By reasonably designing the flow resistance structure before the inlet duct to change the total inlet pressure loss, the engine thrust can be adjusted without reducing the gas temperature and rotor speed, so that when the engine high-pressure rotor speed, low-pressure rotor speed, and gas temperature reach the red line during the redline test, the engine thrust does not exceed the red line, so as to ensure that the parameters affecting the strength and life of key components such as the fan thrust bearing load, the compressor outlet total pressure, and the turbine front temperature do not exceed the limit. The grid is a uniform grid structure, which is formed by an improved design based on the traditional non-uniform inlet distortion mesh structure. Its principle is to block part of the inlet duct flow channel by controlling the density of the grid, thereby uniformly reducing the inlet total pressure of the engine inlet duct section. While reducing the engine thrust through the total pressure loss, the engine high and low pressure rotor speeds and gas temperatures will not be reduced, and the effectiveness of the redline speed and redline temperature special tests will not be affected.

[0005] The purpose of this application is to provide a redline state test method for a turbofan engine.

[0006] Another object of the present application is to provide a test system.

[0007] Another object of the present application is to provide a computer-readable medium.

[0008] Another object of the present application is to provide a computer program product.

[0009] In the first aspect, the redline state test method of the turbofan engine according to the present application includes the following steps: respectively obtaining the first thrust of the engine corresponding to the redline gas temperature of the turbofan engine, the second thrust of the engine corresponding to the redline high-pressure rotor speed, and the third thrust of the engine corresponding to the redline low-pressure rotor speed, and taking the maximum value of the first thrust, the second thrust, and the third thrust as the maximum thrust of the engine; according to the test requirements and the engine bearing strength margin, obtaining the target test thrust corresponding to the engine, and defining the thrust correction coefficient = engine maximum thrust / target test thrust; according to the thrust correction coefficient, determining the total pressure loss coefficient of the turbofan engine inlet; according to the total pressure loss coefficient, setting an air intake grille that meets the total pressure loss coefficient on the inlet of the turbofan engine to form a test structure of the turbofan engine; and performing a redline state test on the test structure of the turbofan engine.

[0010] In one or more embodiments of the test method, according to the total pressure loss coefficient, the step of setting an air intake grille that satisfies the total pressure loss coefficient at the air intake duct of the turbofan engine includes: defining the flow rate of the air intake grille = the total area of ​​a single air intake grille unit / the flow area of ​​a single air intake grille unit; obtaining the relationship between the flow rate and the total pressure loss coefficient of the air intake duct of the turbofan engine, substituting the total pressure loss coefficient determined according to the thrust correction coefficient, and obtaining the flow rate design value.

[0011] In one or more embodiments of the test method, for an air intake grille having the design flow rate value, the strength of the air intake grille is checked according to the material of the air intake grille and the aerodynamic setting of the design point load calculated according to the engine performance model.

[0012] In one or more embodiments of the test method, the material of the air intake grille is stainless steel or hard aluminum alloy, and the surge state adopts an extreme backflow state of 2atm at the outlet and 1atm at the inlet to verify the strength of the air intake grille.

[0013] In one or more embodiments of the test method, the engine bearing strength margin is 5%-10% of the load of the engine bearing corresponding to the rated thrust.

[0014] In one or more embodiments of the test method, the converted rotational speed of the low-pressure rotor of the turbofan engine is constant.

[0015] In one or more embodiments of the test method, the redline state test includes an endurance test and an over-temperature test required for airworthiness.

[0016] In a second aspect, the test system according to the present application includes: a memory for storing instructions executable by a processor; a processor for executing the steps that can be executed by a computer in the redline state test method as described in the first aspect; and a turbofan engine provided with the air intake grille to form a test structure of the turbofan engine.

[0017] In a third aspect, a computer-readable medium according to the present application has a computer program thereon, and the program is executed by a processor to implement the steps in the test method described in the first aspect that can be implemented by a computer program.

[0018] In a fourth aspect, a computer program product according to the present application includes a computer program, which, when executed by a processor, implements the steps in the test method described in the first aspect that can be implemented by a computer program. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features, properties and advantages of the present application will become more apparent through the following description in conjunction with the accompanying drawings and embodiments. In the accompanying drawings, the same reference numerals always represent the same features. It should be noted that these drawings are only examples and are not drawn in proportion. They should not be used to limit the actual scope of protection claimed in the present application. Among them:

[0020] Figure 1 The present invention is a flow chart of a redline state test method for a turbofan engine according to an embodiment.

[0021] Figure 2 A schematic structural diagram of an air intake grille of a redline state test method for a turbofan engine according to an embodiment.

[0022] Figure 3 for Figure 2 Schematic diagram of a single air intake grille unit of an air intake grille.

[0023] Figure 4 A schematic block diagram of a test system according to an embodiment. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to the various embodiments of the application, the examples of which are shown in the accompanying drawings and are described below. Although the application will be described in conjunction with the exemplary embodiments, it should be appreciated that this specification is not intended to limit the application to those exemplary embodiments. On the contrary, the application is intended to not only cover these exemplary embodiments, but also to cover various alternative forms, modified forms, equivalent forms and other embodiments that may be included in the spirit and scope of the application defined by the appended claims.

[0025] In the following description, the directions or positional relationships indicated by "upstream", "downstream" or other directional terms are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present application. In addition, in the specification of the present application, "upstream", "downstream", "front" and "rear" are distinguished based on the general flow direction of air during engine operation, that is, during engine operation, air generally flows from "upstream" to "downstream" and from "front" to "rear", and this direction is also roughly the "intake" to "exhaust" direction of the engine turbine.

[0026] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment" and / or "an embodiment" means a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0027] Flowcharts are used in this application to illustrate the operations performed by the system according to the embodiments of the application. It should be understood that the preceding or following operations are not necessarily performed precisely in order. Other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0028] First of all, the object of this application is a turbofan engine, which can also be called a "turbofan engine". It refers to a gas turbine engine in which the gas ejected from the nozzle and the air exhausted by the fan jointly generate a reaction thrust. It is composed of a compressor, a combustion chamber, a high-pressure turbine (driving the compressor), a low-pressure turbine (driving the fan) and an exhaust system, wherein the compressor, the combustion chamber, and the high-pressure turbine (driving the compressor) are collectively referred to as the core engine. Part of the airflow inhaled by the fan is sent into the core engine (termed "inner duct"), and the other part is directly discharged from the periphery of the core engine to the outside ("external duct"). Therefore, the gas energy of the turbofan engine is distributed to the two exhaust airflows generated by the fan and the combustion chamber respectively.

[0029] "Redline Conditions" refers to the limit values ​​that are not allowed to be exceeded when the engine is operating at the corresponding rated value, including the maximum physical rotor speed, gas temperature, or output shaft torque limit value in steady state and transient state (when in use). For engine type certification, the corresponding redline conditions are specified for each approved engine rating.

[0030] The "Total Pressure Loss Coefficient" refers to the degree of energy loss in a given channel flow or the impact on system performance when flowing through the flow channel. This parameter directly affects the efficiency of the fluid system.

[0031] refer to Figures 1 to 4 As shown, in some embodiments, the redline state test method of a turbofan engine may include the following steps:

[0032] S100. Obtain respectively a first thrust of the engine corresponding to the redline gas temperature of the turbofan engine, a second thrust of the engine corresponding to the redline high-pressure rotor speed, and a third thrust of the engine corresponding to the redline low-pressure rotor speed, and take the maximum value of the first thrust, the second thrust, and the third thrust as the maximum thrust of the engine.

[0033] Specifically, the high-pressure rotor redline speed can be calculated based on the engine performance model. N 2 Redline Thrust value Trust 1 , calculate the speed to reach the low pressure rotor red line N 1 Redline Thrust value Trust 2 , calculate the gas temperature red line EGT Redline Thrust value Trust 3 ,Pick Trust a =Max { Trust 1 , Trust 2 , Trust 3}.

[0034] S200. According to the test requirements and the engine bearing strength margin, obtain the target test thrust corresponding to the engine, and define the thrust correction factor = engine maximum thrust / target test thrust.

[0035] Specifically, the test requirements may be a durability test specified in the airworthiness requirements, which needs to reach the three red line state, such as an over-temperature test specified in the airworthiness requirements, which needs to reach the two red line state. The engine bearing strength margin, for example, may be the fan thrust bearing load margin. In some embodiments, for a turbofan engine, the margin is generally 5%-10% of the engine bearing load corresponding to the rated thrust, which is beneficial to the engine economy. If the margin is too large, it will lead to poor economy.

[0036] Determine the target engine test thrust according to the special test requirements and engine bearing strength limits Trust b , calculate the thrust correction factor σ = Trust a / Trust b .

[0037] S300. Determine the total pressure loss coefficient of the turbofan engine inlet according to the thrust correction coefficient.

[0038] Combined with the engine target test environment pressure P , Ambient temperature T , Ambient humidity RH , determine the total pressure loss coefficient required to be increased in the intake duct based on the engine performance model µ a Specifically, the engine thrust is a function of the compressor pressure ratio. The engine thrust and the pressure ratio are positively correlated. The maximum engine thrust can be determined based on the engine performance model. Trust a and target test thrust Trust b The high pressure compressor outlet pressure P corresponding to these two thrusts 1 , P 2 And the pressure ratio EPR 1 、EPR 2 The maximum thrust can be calculated using the high pressure compressor outlet pressure and the compression ratio Trust a , Target test thrust Trust b The corresponding engine fan inlet total pressure P 1 ' and P 2 ',1-(P 1 ' / P 2 ') to get the total pressure loss coefficient µ a .

[0039] S400. According to the total pressure loss coefficient, an air intake grille satisfying the total pressure loss coefficient is arranged at the air intake duct of the turbofan engine to form a test structure of the turbofan engine.

[0040] Specifically, a pressure reduction design of adding an air intake grille 10 to the air intake duct is adopted, and an improved design is formed on the basis of the air intake distortion mesh structure to form a grille structure covering the air intake duct flow channel. Figure 2 as well as Figure 3 As shown, in some embodiments, the air intake grille 10 is designed to meet the corresponding total pressure loss coefficient µ a The step may be that the air intake grille 10 evenly blocks part of the air intake area to achieve the total pressure loss coefficient of the air intake µ , defining the degree of blocked flow S a / S b As an independent variable affecting the total pressure loss coefficient, such as Figure 3 As shown, the flow rate of the air intake grille 10 is defined as the total area of ​​a single air intake grille unit 101. S a / Flow area of ​​a single air intake grille unit 101 S b ,in, S a =a 2 ，S b =b 2 。

[0041] Obtain the relationship between the flow rate and the total pressure loss coefficient of the turbofan engine inlet, substitute the total pressure loss coefficient determined according to the thrust correction coefficient, and obtain the flow rate design value. For example, modeling and calculating different flow rates of the flow channel S a / S b Total pressure loss coefficient under the condition µ ,get S a / S b The relationship curve of the input target total pressure loss coefficient µ a , and obtain the design value of circulation ( S a / S b ) D .

[0042] S500. Perform a redline state test on the test structure of the turbofan engine.

[0043] The above steps can reduce the engine thrust by reducing the total pressure loss without reducing the engine high and low pressure rotor speed and gas temperature, and will not affect the effectiveness of the red line speed and red line temperature special test. The principle is that the engine inlet total pressure is reduced by blocking part or all of the inlet duct flow, so that the pressure of each section in the engine flow duct is reduced. Turbofan engines usually use a constant low pressure rotor conversion speed N 1R The control rate is to maintain the conversion speed of the low-pressure rotor when the inlet total pressure drops. N 1R If the fuel pressure is constant, the control system will increase the fuel flow rate of the fuel main pipe to increase the turbine output power and the high-pressure rotor speed. The increased fuel flow rate will also cause the turbine pre-temperature and the gas exhaust temperature to increase.

[0044] The beneficial effect of adopting the above embodiment is that by reasonably designing the flow resistance structure before the inlet duct to change the total intake pressure loss, the engine thrust can be adjusted without reducing the gas temperature and the rotor speed. When the engine high-pressure rotor speed, the low-pressure rotor speed, and the gas temperature all reach the red line during the red line test, the engine thrust does not exceed the red line by too much, so as to ensure that the parameters affecting the strength and life of key components such as the fan thrust bearing load, the compressor outlet total pressure, and the turbine front temperature do not exceed the limit.

[0045] In some embodiments, the air intake grille 10 is further subjected to strength verification, which may specifically include the following steps:

[0046] For the design value of the flow rate ( S a / S b ) D The air intake grille 10 is provided, and the strength of the air intake grille 10 is checked according to the material of the air intake grille 10 and the aerodynamic force setting calculated according to the engine performance model of the design point load.

[0047] In some embodiments, the material of the air intake grille 10 may be stainless steel or hard aluminum alloy, the design point load is set according to the aerodynamic force calculated by the engine performance model, and the surge state is taken as the outlet 2 atm , Import 1 atm The strength of the air intake grille is checked in the limit backflow state, and the target safety factor must be greater than 1. This can ensure the reliability of the air intake grille 10 during the test, and also prevent the air intake grille from being damaged during the test, causing damage to the engine and affecting the safety of the test.

[0048] It can be understood that in some embodiments, Figure 4 As shown, the present application also provides a test system 100, including a turbofan engine 40, provided with the above-described air intake grille 10, forming a test structure of the turbofan engine. The test system 100 also includes a memory 20 for storing instructions executable by a processor; a processor 30 for executing the steps that can be executed by a computer in the redline state test method described in the above embodiment.

[0049] It can be understood that it should be noted that the above-mentioned memory and processor are not limited to a specific memory or processor. For example, in some cases, both the memory and the processor can have a distributed structure. For example, they can include a memory and a processor located on the test device side and the backend cloud, respectively, and the test device side and the backend cloud jointly implement the above-mentioned test method. Furthermore, in an embodiment using a distributed structure, each step can adjust the specific execution terminal according to actual conditions, and the specific scheme of each step implemented in a specific terminal should not limit the scope of protection of this application.

[0050] Another aspect of the present application further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the steps of the test method described in the above embodiment are implemented. Please refer to the above description for details, which will not be repeated here.

[0051] In addition, it can be understood that the above-mentioned computer-readable storage medium can also be in a system form, that is, it includes multiple computer-readable storage sub-media, so as to jointly implement the steps of the design method described above through multiple computer-readable storage media.

[0052] In addition, another aspect of the present application further provides a computer program product, including a computer program, which, when executed by a processor, implements the steps of the test method described in the above embodiment. Please refer to the above description for details, which will not be repeated here.

[0053] In summary, the beneficial effects of the redline state test method, test system, computer readable medium, and computer program product of the turbofan engine introduced in the above embodiments include but are not limited to: by reasonably designing the inlet front flow resistance structure to change the inlet total pressure loss, the engine thrust can be adjusted without reducing the gas temperature and rotor speed, so that when the redline test is performed, when the engine high-pressure rotor speed, low-pressure rotor speed, and gas temperature all reach the redline, the engine thrust does not exceed the redline, so as to ensure that the parameters affecting the strength and life of key components such as the fan thrust bearing load, the compressor outlet total pressure, and the turbine front temperature do not exceed the limit. The grid is a uniform grid structure, which is formed by an improved design based on the traditional non-uniform inlet distortion mesh structure. The principle is to block part of the inlet flow channel by controlling the density of the grid, thereby uniformly reducing the inlet total pressure of the engine inlet cross section. While reducing the engine thrust through the total pressure loss, the engine high and low pressure rotor speeds and gas temperatures will not be reduced, and the effectiveness of the redline speed and redline temperature special tests will not be affected.

[0054] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0055] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0056] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any media that facilitates the transfer of a computer program from one place to another. Storage media may be any available media that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0057] Although the present application is disclosed as above with preferred implementation modes, it is not intended to limit the present application. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modification, equivalent change and modification made to the above implementation modes according to the technical essence of the present application without departing from the content of the technical solution of the present application shall fall within the protection scope defined by the claims of the present application.

Claims

1. A redline state test method for a turbofan engine, characterized in that: The following steps are involved: Respectively obtain a first thrust of the engine corresponding to the redline gas temperature of the turbofan engine, a second thrust of the engine corresponding to the redline high-pressure rotor speed, and a third thrust of the engine corresponding to the redline low-pressure rotor speed, and take the maximum value of the first thrust, the second thrust, and the third thrust as the maximum thrust of the engine; According to the test requirements and the engine bearing strength margin, the target test thrust corresponding to the engine is obtained, and the thrust correction factor is defined as engine maximum thrust / target test thrust; Determining the total pressure loss coefficient of the turbofan engine inlet according to the thrust correction coefficient; According to the total pressure loss coefficient, an air intake grille (10) corresponding to the total pressure loss coefficient is arranged at the air intake duct of the turbofan engine to form a test structure of the turbofan engine; wherein the step of arranging the air intake grille (10) corresponding to the total pressure loss coefficient at the air intake duct of the turbofan engine comprises: The flow rate of the air intake grille (10) is defined as: the total area of ​​a single air intake grille unit (101) / the flow area of ​​a single air intake grille unit (101); Obtaining a relationship between the flow rate and the total pressure loss coefficient of the turbofan engine inlet, substituting the total pressure loss coefficient determined according to the thrust correction coefficient into the relationship, and obtaining a flow rate design value; A redline state test is performed on the test structure of the turbofan engine.

2. The red line state test method according to claim 1, characterized in that: For an air intake grille (10) having the flow rate design value, the strength of the air intake grille (10) is checked based on the material of the air intake grille (10) and the aerodynamic force setting calculated according to the engine performance model at the design point load.

3. The red line state test method according to claim 2, characterized in that: The material of the air intake grille (10) is stainless steel or hard aluminum alloy. The surge state adopts an extreme backflow state of 2 atm at the outlet and 1 atm at the inlet, and the strength of the air intake grille (10) is checked.

4. The red line state test method according to claim 1, characterized in that: The engine bearing strength margin is 5%-10% of the engine bearing load corresponding to the rated thrust.

5. The red line state test method according to claim 1, characterized in that: The converted rotation speed of the low-pressure rotor of the turbofan engine is constant.

6. The red line state test method according to claim 1, characterized in that: The redline status test includes endurance test and over-temperature test required for airworthiness.

7. A test system (100), characterized in that: include: A memory (20) for storing instructions executable by a processor; A processor (30), configured to execute the steps executable by a computer in the redline status test method according to any one of claims 1 to 6; A turbofan engine (40) is provided with the air intake grille (10) to form a test structure of the turbofan engine.

8. A computer readable medium having a computer program thereon, characterized in that The program is executed by a processor to implement the steps that can be executed by a computer in the redline status test method as described in any one of claims 1 to 6.

9. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the computer program implements the steps that can be executed by a computer in the redline status test method as described in any one of claims 1 to 6.

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