Method for determining exhaust temperature margin of aero-engine in takeoff state

Abstract

The invention provides an aero-engine takeoff state exhaust temperature margin determination method, and belongs to the technical field of aero-engines, and the method comprises the steps: obtaining engine thrust demands under different air inlet temperature conditions in a takeoff state, determining rotation speed control rules corresponding to different air inlet temperature conditions, and determining the takeoff state exhaust temperature margin of the aero-engine; a relation curve of the exhaust temperature and the air inlet temperature of engine theoretical design is constructed; determining installation use factors influencing the exhaust temperature in the take-off state and the influence quantity of the installation use factors, and determining the exhaust temperature margin; according to an engine theory, designing a relation curve of the exhaust temperature and the intake temperature and an exhaust temperature margin to obtain a relation curve of an exhaust temperature limit value and the intake temperature; and calculating overall parameters corresponding to the exhaust temperature limit values under different air inlet temperature conditions, carrying out engine strength life analysis based on the overall parameters, judging whether the engine strength life meets requirements or not, and if the engine strength life does not meet the requirements, adjusting the thrust demand or the exhaust temperature margin of the engine in the take-off state until the engine strength life meets the requirements.

Description

Technical Field

[0001] The present application relates to the field of aero-engines, and in particular to a method for determining the exhaust temperature margin of an aero-engine in take-off state. Background Art

[0002] The exhaust temperature margin of an aircraft engine refers to the difference between the maximum allowable exhaust temperature at steady state, under the same inlet temperature conditions, and the exhaust temperature at intermediate and higher engine states, measured through steady-state performance recording, ignoring aircraft installation losses, aircraft bleed air, and power draw. The greater the exhaust temperature margin, the better the engine's thrust performance is maintained. The aircraft's takeoff is a critical step in the entire flight process, and the ability to achieve sufficient takeoff thrust is a crucial factor in ensuring safe takeoff. This is especially true for non-land-based aircraft, where the strict restrictions on takeoff environment and distance make maintaining good takeoff thrust characteristics crucial. Therefore, the impact of the exhaust temperature margin during takeoff must be fully considered during aircraft engine design.

[0003] Existing aircraft engine takeoff exhaust temperature margins fail to fully consider the impact of installation and use factors. The typical exhaust temperature margin is 20°C to 30°C, which is too small. After installation and use, the engine will quickly reach the exhaust temperature limit. The engine speed will fall below the design value, resulting in a significant reduction in takeoff thrust, or even failing to meet the aircraft's minimum takeoff thrust. In the worst case, this will increase the takeoff distance. In the worst case, the aircraft will not be able to take off normally, resulting in a flight accident. In addition, as users' requirements for high-speed warm-up before takeoff become increasingly stringent (shortened warm-up time or no warm-up), the increase in takeoff exhaust temperature (approximately 40°C to 90°C) caused by insufficient or no warm-up far exceeds the current exhaust temperature margin value. However, excessive exhaust temperature margins increase engine design difficulty, increase structural size and weight, and increase fuel consumption. Summary of the Invention

[0004] The purpose of the present application is to provide a method for determining exhaust gas temperature margin of an aircraft engine in takeoff state, so as to solve or alleviate at least one problem in the background technology.

[0005] The technical solution of the present application is: a method for determining the exhaust temperature margin of an aircraft engine in takeoff state, comprising:

[0006] Obtaining engine thrust requirements under different intake air temperature conditions in a takeoff state, determining speed control laws corresponding to different intake air temperature conditions based on the engine thrust requirements, and constructing a relationship curve between the theoretical design exhaust temperature and the intake air temperature of the engine under the speed control law;

[0007] determining an installed use factor and its influence amount that affects the exhaust temperature in a takeoff state, and determining a takeoff exhaust temperature margin based on the installed use factor and its influence amount;

[0008] Obtaining a curve of relationship between the exhaust temperature limit value and the intake temperature of the engine based on the theoretical design curve of the exhaust temperature and the intake temperature and the exhaust temperature margin in the takeoff state;

[0009] Calculate the overall parameters corresponding to the engine exhaust temperature limit values ​​under different intake temperature conditions, perform engine strength and life analysis based on the overall parameters, and determine whether the engine strength and life meet the requirements. If not, adjust the takeoff thrust requirement or exhaust temperature margin until the engine strength and life meet the requirements.

[0010] Preferably, the different intake air temperature conditions include a standard day temperature of T2=15°C, a hot day temperature of T2≥30°C, and an extremely hot day temperature of T2≥45°C, wherein T2 is the intake air temperature.

[0011] Preferably, the process of determining the speed control law corresponding to different intake air temperature conditions based on the engine thrust demand includes:

[0012] An intake temperature threshold is determined. When the engine intake temperature is less than or equal to the intake temperature threshold, the engine is controlled according to the equal-conversion speed. When the engine intake temperature is greater than the intake temperature threshold, the speed is controlled to meet the engine thrust demand under the intake temperature condition, and the speed corresponding to the non-intake temperature condition transitions linearly between the speeds corresponding to different intake temperature conditions.

[0013] Preferably, the intake air temperature threshold is 0-20°C.

[0014] Preferably, the installed use factors affecting the exhaust temperature in the takeoff state include: intake conditions, aircraft bleed air and power extraction, engine operating state and time before takeoff, and engine performance degradation;

[0015] Among them, the influence of intake conditions on the exhaust temperature of the engine at takeoff state ΔT 6X1 Obtained through distortion test; the effect of aircraft bleed air and power extraction on the exhaust temperature of the engine at takeoff state ΔT 6X2 Obtained through the aircraft bleed air and power extraction commissioning test of the whole aircraft; the influence of the engine operating state and time before takeoff on the engine takeoff exhaust temperature ΔT 6X3 The effect of engine performance degradation on the exhaust temperature of the engine at takeoff state ΔT is obtained through ground takeoff simulation tests with different warm-up speeds and times. 6X4 Obtained through endurance test or statistical results of engines of similar models.

[0016] Preferably, the takeoff exhaust temperature margin ΔT 6YD satisfy:

[0017] ΔT 6YD =ΔT 6X1 +ΔT 6X2 +ΔT 6X3 +ΔT 6X4 .

[0018] Preferably, the relationship curve between the engine exhaust temperature limit value and the intake temperature is obtained by superimposing the relationship curve between the engine theoretical design exhaust temperature and the intake temperature on the exhaust temperature margin value in the takeoff state.

[0019] The present invention fully considers the factors of aircraft engine takeoff exhaust temperature margin determination, comprehensively considering aircraft bleed air and power extraction, intake distortion, usage procedures (engine operating status and time before takeoff), performance degradation, etc., and obtains the engine exhaust temperature rise caused by different installation and usage factors through theoretical calculation, experimental verification and statistical methods, thereby obtaining the exhaust temperature margin required for takeoff during the engine's life cycle, ensuring that the engine's takeoff thrust meets the aircraft's usage requirements during its service life, providing a basis for the engine's strength life design and reliability design, thereby ensuring the smooth development of model development and reducing model development costs. The method is simple to implement, easy to improve, and has wide adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0021] Figure 1 Schematic diagram of the method for determining the exhaust temperature margin of an aircraft engine in takeoff state according to the present application.

[0022] Figure 2 The theoretical design exhaust temperature T6 and intake temperature T of the engine in one embodiment of the present application are 2的 Schematic diagram of the relationship curve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0024] This application proposes a method for determining the exhaust temperature margin of an aircraft engine during takeoff, based on aircraft requirements and taking into account factors such as aircraft bleed air and power extraction, intake distortion, operating status (engine operating status and time before takeoff), and performance degradation. The method comprises the following steps:

[0025] S10, obtaining engine thrust requirements under different intake air temperature conditions in a takeoff state, determining corresponding engine speed control laws based on the engine thrust requirements under different intake air temperature conditions in the takeoff state, and constructing engine exhaust temperatures at different intake air temperature points in the takeoff state based on the speed control laws.

[0026] In this application, the engine design data or coordination with the user can be used to obtain the different intake air temperature conditions (T 2X1 、T 2X2 ,...,T 2XN ) of the engine thrust requirement (F X1 、F X2 ,...,F XN ).

[0027] Typically, typical takeoff engine thrust requirements for intake air temperatures include standard weather (T2 = 15°C), hot weather (T2 ≥ 30°C), and extremely hot weather (T2 ≥ 45°C). This ensures the engine can provide sufficient takeoff thrust under these various intake air temperatures, especially during hot weather, to ensure safe takeoff.

[0028] Based on the engine thrust requirements under different intake air temperature conditions in the takeoff state, the speed control rules corresponding to different intake air temperature conditions in the takeoff state are constructed, including:

[0029] 1) Determine the intake air temperature threshold. To fully utilize the engine performance, when the intake air temperature is less than or equal to the intake air temperature threshold, the engine is controlled at the same converted speed;

[0030] In some embodiments of the present application, the intake air temperature threshold may be set to 0-20° C. For example, the intake air temperature threshold is the same as the standard day temperature, which is set to 15° C.

[0031] 2) When the intake air temperature is greater than the intake air temperature threshold, the speed control law is to meet the intake air temperature conditions specified by the index requirements (T 2X1 、T 2X2 ...T 2XN ) of the engine thrust requirements, and the speed corresponding to the other intake air temperatures under different intake air temperature conditions (T 2X1 、T 2X2 ...T 2XN ) corresponding to the speed of linear transition.

[0032] According to the speed control law corresponding to different intake air temperature conditions in the takeoff state constructed by the above process, the theoretical design exhaust temperature T of the engine is obtained under sea level conditions, no aircraft bleed air and power extraction conditions. 6设计 The relationship curve with the engine intake temperature T2 can be obtained through theoretical calculation or ground steady-state performance test of the whole machine.

[0033] S20 , determining the installed use factors and their impact amounts that affect the exhaust temperature in the takeoff state, and determining the exhaust temperature margin in the takeoff state based on the installed use factors and their impact amounts.

[0034] In this application, the factors affecting the exhaust temperature at takeoff include: air intake conditions (distortion of the aircraft inlet outlet after installation), aircraft bleed air and power extraction, engine operating status and time before takeoff, performance degradation, etc. Among them, the influence of air intake conditions (distortion) on engine exhaust temperature ΔT 6X1 The effect of aircraft bleed air and power extraction on engine exhaust temperature (ΔT 6X2 ) can be obtained through the aircraft bleed air and power extraction commissioning test of the whole aircraft; the influence of the engine operating state and time before takeoff on the engine exhaust temperature (ΔT 6X3 ) can be obtained through special ground tests (takeoff simulation tests with different warm-up speeds and times); the effect of engine performance degradation on engine exhaust temperature (ΔT 6X4 ) can be obtained through endurance test or statistical results of engines of similar models.

[0035] Based on the above-mentioned installation and use factors and their influencing quantities, the engine exhaust temperature margin at takeoff is obtained, that is, ΔT 6YD =ΔT 6X1 +ΔT 6X2 +ΔT 6X3 +ΔT 6X4 .

[0036] S30, exhaust temperature T is designed according to engine theory 6设计 The relationship curve between the engine exhaust temperature limit value and the intake air temperature is obtained from the relationship curve of the engine intake air temperature T2 and the engine exhaust temperature margin in the takeoff state, thereby determining the exhaust temperature limit value under different intake air temperature conditions in the takeoff state.

[0037] like Figure 2 The solid line curve is the relationship curve between the theoretical design exhaust temperature T6 of the engine and the intake temperature T2 obtained in step S20. The engine exhaust temperature margin ΔT in the takeoff state is superimposed (i.e., shifted upward) on this relationship curve. 6YD Get the engine exhaust temperature limit value T 6max The relationship curve with the intake air temperature T2, that is, T6max =T 6设计 +ΔT 6YD , thus obtaining the exhaust temperature limit value T of the engine at takeoff 6max =f(T2).

[0038] S40, calculating the exhaust temperature limit value T of the engine under different intake air temperature conditions 6max Corresponding engine overall parameters, based on which strength life analysis is performed to determine whether the strength life meets the requirements; if not, the engine thrust requirements are coordinated with the user or the exhaust temperature margin ΔT is adjusted (usually reduced) 6YD , until the strength and life design requirements are met.

[0039] The present invention fully considers the factors of aircraft engine takeoff exhaust temperature margin determination, comprehensively considering aircraft bleed air and power extraction, intake distortion, usage procedures (engine operating status and time before takeoff), performance degradation, etc., and obtains the engine exhaust temperature rise caused by different installation and usage factors through theoretical calculation, experimental verification and statistical methods, thereby obtaining the exhaust temperature margin required for takeoff during the engine's life cycle, ensuring that the engine's takeoff thrust meets the aircraft's usage requirements during its service life, providing a basis for the engine's strength life design and reliability design, thereby ensuring the smooth development of model development and reducing model development costs. The method is simple to implement, easy to improve, and has wide adaptability.

[0040] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for determining the exhaust gas temperature margin of an aircraft engine at takeoff, characterized in that: include: Obtaining engine thrust requirements under different intake air temperature conditions in a takeoff state, determining speed control laws corresponding to different intake air temperature conditions based on the engine thrust requirements, and constructing a relationship curve between the theoretical design exhaust temperature and the intake air temperature of the engine under the speed control law; determining an installed use factor and its influence amount that affects the exhaust temperature in a takeoff state, and determining a takeoff exhaust temperature margin based on the installed use factor and its influence amount; Obtaining a curve of relationship between the exhaust temperature limit value and the intake temperature of the engine based on the theoretical design curve of the exhaust temperature and the intake temperature and the exhaust temperature margin in the takeoff state; Calculate the overall parameters corresponding to the engine exhaust temperature limit values ​​under different intake temperature conditions, perform engine strength and life analysis based on the overall parameters, and determine whether the engine strength and life meet the requirements. If not, adjust the takeoff engine thrust demand or exhaust temperature margin until the engine strength and life meet the requirements.

2. The method for determining the exhaust gas temperature margin of an aircraft engine in takeoff state according to claim 1, wherein: The different intake air temperature conditions include a standard day temperature of T2=15°C, a hot day temperature of T2≥30°C, and an extremely hot day temperature of T2≥45°C, wherein T2 is the intake air temperature.

3. The method for determining the exhaust gas temperature margin of an aircraft engine in takeoff state according to claim 2, wherein: The process of determining the speed control law corresponding to different intake air temperature conditions based on the engine thrust demand includes: An intake temperature threshold is determined. When the engine intake temperature is less than or equal to the intake temperature threshold, the engine is controlled according to the equal-conversion speed. When the engine intake temperature is greater than the intake temperature threshold, the speed is controlled to meet the engine thrust demand under the intake temperature condition, and the speed corresponding to the non-intake temperature condition transitions linearly between the speeds corresponding to different intake temperature conditions.

4. The method for determining the exhaust gas temperature margin of an aircraft engine in takeoff state according to claim 3, wherein: The intake air temperature threshold is 0-20°C.

5. The method for determining the exhaust gas temperature margin of an aircraft engine in takeoff state according to claim 3, wherein: The installed operating factors affecting the exhaust gas temperature in the takeoff state include: air intake conditions, aircraft bleed air and power extraction, engine operating state and time before takeoff, and engine performance degradation; Among them, the influence of intake conditions on the exhaust temperature of the engine at takeoff state ΔT 6X1 Obtained through distortion test; the effect of aircraft bleed air and power extraction on the exhaust temperature of the engine at takeoff state ΔT 6X2 Obtained through the aircraft bleed air and power extraction commissioning test of the whole aircraft; the influence of the engine operating state and time before takeoff on the engine takeoff exhaust temperature ΔT 6X3 Obtained through ground takeoff simulation tests with different warm-up speeds and times; the effect of engine performance degradation on the exhaust temperature of the engine at takeoff state ΔT 6X4 Obtained through endurance test or statistical results of engines of similar models.

6. The method for determining the exhaust gas temperature margin of an aircraft engine in takeoff state according to claim 5, wherein: The takeoff exhaust temperature margin ΔT 6YD satisfy: ΔT 6YD =ΔT 6X1 +ΔT 6X2 +ΔT 6X3 +ΔT 6X4 。 7. The method for determining the exhaust gas temperature margin of an aircraft engine in takeoff state according to claim 6, wherein: The relationship curve between the engine exhaust temperature limit value and the intake air temperature is obtained by superimposing the relationship curve between the engine theoretical design exhaust temperature and the intake air temperature and the exhaust temperature margin value in the takeoff state.

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