A design method for engine starting fuel supply law based on core engine

Abstract

This application belongs to the field of engine fuel supply design, and is a design method for the engine starting fuel supply law based on the core engine. By using the mature core engine starting fuel supply law, the relationship between the starting fuel supply and the compressor outlet pressure ratio and the converted high-pressure rotor speed n' is found. R The relationship with the low-pressure converted speed is obtained through steady-state calculation of the compressor inlet temperature of the engine. Then, the design criterion for the engine starting fuel supply law is obtained through the core engine starting fuel supply law, and the relationship with the converted compressor inlet speed is established. Subsequently, the relationship between the converted high-pressure rotor speed and the converted compressor inlet speed is found through engine testing, so as to find the relationship between the engine starting fuel supply law and the core engine starting fuel supply law, and establish the engine starting fuel supply law; reducing the test risk, improving the test efficiency, and reducing the test cost.

Description

Technical Field

[0001] The present application belongs to the field of engine fuel supply design, and in particular relates to a method for designing a fuel supply law for engine starting based on a core engine. Background Art

[0002] The core engine is the most important part of the engine, including the components and systems with the highest temperature, maximum pressure and highest speed in the engine system. Therefore, the development of the core engine is also the most important link in the engine development process; during the development process, the engine test work is generally carried out after completing sufficient core engine test verification.

[0003] Starting is the first stage in the core engine or engine test process. At present, the accuracy of transient state simulation calculation is limited and cannot meet engineering applications. Therefore, the core engine or engine starting process is generally repeated through debugging to meet the test requirements, without drawing on the starting fuel supply experience accumulated in the core engine test.

[0004] The existing technical solution is to conduct core engine and engine start-up and debugging tests separately, and meet the test requirements through repeated debugging. There are many problems with this method, and the main problems are as follows: First, the test risk is high. The engine starting process is very complicated. If the starting oil volume is too low, cold suspension will occur, resulting in starting failure. If the starting oil volume is too high, overheating will occur, resulting in turbine ablation failure. These failures are often unrecoverable, which greatly increases the test risk. Second, the test efficiency is low. To achieve a satisfactory starting process, it takes a lot of time to conduct starting and debugging tests, and it affects the progress of other test projects, reducing the test efficiency. Second, the test cost is high. Spending a lot of time on starting and debugging tests will inevitably increase energy consumption costs and personnel costs, and increase test costs.

[0005] Therefore, how to improve engine test efficiency and reduce test risks is a problem that needs to be solved. Summary of the invention

[0006] The purpose of this application is to provide a method for designing an engine starting fuel supply law based on a core engine, so as to solve the problems of high test risk, low test efficiency and high test cost when performing starting tests on existing engines in the prior art.

[0007] The technical solution of the present application is: a method for designing the starting fuel supply law of an engine based on a core engine, comprising: conducting a core engine starting and debugging test, obtaining the starting fuel supply power of the core engine, and establishing the starting fuel supply W′ fac Ratio of compressor outlet pressure P′3 and high pressure rotor conversion speed n′ R The relationship f1(n′ R );Get the engine compressor inlet temperature T 25 Conversion speed n with low pressure1R The relationship f2(n 1R ); Determine the engine starting fuel supply law design criteria according to the core engine starting fuel supply law, and obtain the engine starting fuel supply law W fac / P3 and high pressure rotor conversion speed n' R Converted speed n to compressor inlet speed 2R25 Relationship; Get the high-pressure rotor conversion speed n' R and the engine high pressure compressor rotor conversion speed n 2R The relationship f7(n 2R );According to the high pressure rotor speed n' R Converted speed n to the engine high pressure compressor rotor 2R The relationship between the engine starting fuel supply law W is obtained fac / P3 and core engine starting fuel supply law W′ fac / P′3; obtain the engine starting fuel supply law.

[0008] Preferably, the engine compressor inlet temperature T 25 Conversion speed n with low pressure 1R The calculation method is:

[0009] Convert the speed n according to the low-pressure rotor 1R The engine throttling characteristics are calculated every 5% step; based on the engine throttling characteristics calculation results, the engine compressor inlet temperature T is obtained. 25 Conversion speed n with low pressure 1R Relationship, specifically:

[0010] T 25 / T1=f2(n 1R )

[0011] Where T1 is the engine inlet temperature; after calculating the engine throttling characteristics, we get:

[0012]

[0013] Preferably, the high-pressure rotor conversion speed n' R Converted speed n to compressor inlet speed 2R25 The relationship is:

[0014]

[0015] Among them, T 25DesignPoint is the design point compressor inlet temperature; the engine starting fuel supply law is:

[0016] W′ fac / W′3=f6(n′ R )==W fac / W3=f6(n 2R25 )

[0017] Preferably, the high-pressure rotor conversion speed n' R and the engine high pressure compressor rotor conversion speed n 2R The relationship is:

[0018]

[0019] Where T1 is the engine inlet temperature.

[0020] Preferably, the engine starting fuel supply rule W fac / P3 and core engine starting fuel supply law W′ fac The corresponding relationship of / P3′ is: Where T1 is the engine inlet temperature.

[0021] Preferably, the starting fuel supply rule of the engine is:

[0022] When the engine is in the low speed state during starting:

[0023] W fac / P3=f1(f7(n 2R ))

[0024] When the engine is in the high speed state during starting:

[0025] W fac / P3=f1(f7(n 2R ))×(f2(n 1R )) 0.5

[0026] The present invention discloses a method for designing the starting fuel supply law of an engine based on a core engine. By utilizing the mature starting fuel supply law of the core engine, the starting fuel supply and the compressor outlet pressure ratio and the high-pressure rotor conversion speed n′ are found. R The relationship between the compressor inlet temperature and the low-pressure converted speed is obtained through steady-state calculation, and then the engine starting fuel supply law design criteria are obtained through the core engine starting fuel supply law, and the relationship with the compressor inlet converted speed is established. Then, the relationship between the high-pressure rotor converted speed and the compressor inlet converted speed is found through engine test, so as to find the relationship between the engine starting fuel supply law and the core engine starting fuel supply law, and establish the engine starting fuel supply law; reduce test risks, improve test efficiency, and reduce test costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0028] Figure 1 This is a schematic diagram of the overall process of this application;

[0029] Figure 2 This is a schematic diagram of the fuel supply rule for the core engine starting of this application;

[0030] Figure 3 This is a schematic diagram of the relationship between the compressor inlet temperature and the low-pressure converted speed of the engine of this application. DETAILED DESCRIPTION

[0031] 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.

[0032] A method for designing a starting fuel supply law for an engine based on a core engine determines the starting fuel supply law for an engine based on the core engine by considering the aerodynamic matching relationship between the engine and the core engine after adding low-pressure components on the basis of the mature starting fuel supply law for the core engine.

[0033] In actual engineering applications, the starting modes of core engines or engines are divided into open-loop starting mode and closed-loop starting mode. For newly developed engines, in order to ensure test safety, the open-loop starting mode is generally selected; therefore, this method mainly designs the fuel supply law for the open-loop starting mode, and the relevant parameter definitions are shown in Table 1.

[0034] Table 1 Parameter definition

[0035]

[0036]

[0037] like Figure 1 As shown, the specific steps include:

[0038] Step S100, perform core engine startup debugging test, obtain core engine startup fuel supply power, establish startup fuel supply W′ fac Ratio to compressor outlet pressure P3′ and high pressure rotor conversion speed n′ R The relationship f1(n′ R );

[0039] like Figure 2 As shown in the figure, the core engine is usually started at normal temperature and pressure. The core engine start-up oil supply law is expressed as the start-up oil supply W' fac Ratio to compressor outlet pressure P3′ and high pressure rotor conversion speed n′ R The relationship between , see formula (1).

[0040] W′ fac / P′3=f1(n′R ) (1)

[0041] See the schematic diagram of the starting fuel supply law for standard atmospheric conditions (temperature) at sea level. Figure 1 .

[0042] Step S200, obtaining the compressor inlet temperature T of the engine 25 Conversion speed n with low pressure 1R The relationship f2(n 1R );

[0043] like Figure 3 As shown, through the steady-state calculation program, under standard atmospheric conditions at sea level, the low-pressure rotor conversion speed n 1R The engine throttling characteristics are calculated every 5% step. According to the calculation results of the engine throttling characteristics, the relationship between the engine compressor inlet temperature and the low-pressure conversion speed is obtained, which is:

[0044] T 25 / T1=f2(n 1R ) (2)

[0045] After calculating the engine throttling characteristics, we get:

[0046]

[0047] Step S300, determining the engine starting fuel supply law design criteria according to the core engine starting fuel supply law, and obtaining the engine starting fuel supply law W fac / P3 and high pressure rotor conversion speed n′ R Converted speed n to compressor inlet speed 2R25 The relationship between

[0048] On the basis of the mature core engine starting fuel supply law, the design method of the engine starting fuel supply law is to ensure that the common working point, main combustion chamber oil-gas ratio and other parameters are consistent with the core engine during the starting process at the same conversion speed, so as to obtain the engine starting fuel supply law W fac / P3 and high pressure rotor conversion speed n′ R Converted speed n to compressor inlet speed 2R25 The relationship is as follows:

[0049]

[0050] W′ 2R25 =f3(n′ R )==W 2R25 =f3(n 2R25 ) (5)

[0051] π′ c =f4(n′ R)==π c =f4(n 2R25 ) (6)

[0052] W′ 2R25 =f5(n′ R )×π′ c = =W 2R25 =f5(n 2R25 )×π c (7)

[0053] The fuel supply rule for engine starting is:

[0054] W′ fac / W3=f6(n′ R )==W fac / W3=f6(n 2R25 ) (8)

[0055] Step S400, obtaining the high-pressure rotor conversion speed n' R and the engine high pressure compressor rotor conversion speed n 2R The relationship f7(n 2R );

[0056] Since the compressor inlet total temperature T 25 There is a response constant. During the engine test, the high-pressure compressor rotor conversion speed n is generally selected. 2R Replace the compressor inlet conversion speed n 2R25 As control parameters, specifically:

[0057] n′ R =n 2R25 =f7(n 2R ) (9)

[0058]

[0059] Step S500, converting the speed n' of the high-pressure rotor R Converted speed n to the engine high pressure compressor rotor 2R The relationship between the engine starting fuel supply law W is obtained fac / P3 and core engine starting fuel supply law W′ fac / P3′ relation;

[0060] The design method of the engine starting fuel supply law is to ensure that the fuel-air ratio of the main combustion chamber is consistent with that of the core engine under the same conversion speed during the starting process. For details, see formula (8). Under the condition of the same bleed air ratio, it can be converted to the physical mass flow rate of the compressed air inlet. The calculation method of the relationship between the engine and the core engine starting fuel supply law is:

[0061] W fac / (W25 × bleed )=W′ fac / (W′ 25 ×x′ bleed ) (11)

[0062] Convert the compressor inlet physical mass flow rate to the compressor inlet conversion flow rate to obtain:

[0063]

[0064] Substituting into formula (7), it is converted to:

[0065]

[0066] Extract the oil supply law parameter W fac / P3, the relationship between the engine starting fuel supply law and the core engine starting fuel supply law is obtained as follows:

[0067]

[0068]

[0069] Step S600, obtaining the engine starting fuel supply rule.

[0070] When the engine is in the low speed state during starting (n 2R ≤35%), compressor inlet temperature T 25 It is basically consistent with the engine inlet temperature T1. Formulas (1), (9) and (15) are combined to obtain the starting fuel supply law. For details, see formula (16):

[0071] W fac / P3=f1(f7(n 2R )) (16)

[0072] When the engine is in the high speed state during the starting process (n 2R >35%), compressor inlet temperature T 25 The relationship between the temperature and the engine inlet temperature T1 cannot be ignored. Formulas (1), (2), (9) and (15) are combined to obtain the starting fuel supply law. For details, see formula (17):

[0073] W fac / P3=f1(f7(n 2R ))×(f2(n lR )) 0.5 (17)

[0074] When designing the starting fuel supply law of an aircraft engine, by using the mature core engine starting fuel supply law, we can find the starting fuel supply and compressor outlet pressure ratio and high pressure rotor conversion speed n' R The relationship between the compressor inlet temperature and the low-pressure converted speed is obtained through steady-state calculation, and then the engine starting fuel supply law design criteria are obtained through the core engine starting fuel supply law, and the relationship with the compressor inlet converted speed is established. Then, the relationship between the high-pressure rotor converted speed and the compressor inlet converted speed is found through engine test runs, so as to find the relationship between the engine starting fuel supply law and the core engine starting fuel supply law, and establish the engine starting fuel supply law.

[0075] It has the following advantages:

[0076] 1) Reduce test risk. This method determines the engine starting fuel supply law based on the core engine test starting fuel supply law, ensuring that during the starting process, the engine compressor and main combustion chamber components have similar working conditions to the core engine, reducing the risk of the engine starting test;

[0077] 2) Improve test efficiency. Compared with the original test method, since repeated debugging is not required, it can be completed only once according to the steps, which can reduce the number of start-up debugging and improve test efficiency;

[0078] 3) Reduce test costs. This method reduces the number of startup and debugging times, reduces labor costs and energy consumption costs, and greatly reduces test costs.

[0079] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for designing the fuel supply law of engine starting based on a core engine, characterized in that: include: Conduct core engine start-up and debugging tests, obtain the core engine start-up fuel supply power, and establish the start-up fuel supply volume W f ' ac and compressor outlet pressure P3 ' Ratio and high pressure rotor conversion speed n' R The relationship f1(n' R ); Get the engine compressor inlet temperature T 25 Conversion speed n with low pressure rotor 1R The relationship f2(n 1R ); According to the core engine starting fuel supply law, the design criteria for the engine starting fuel supply law are determined, and the engine starting fuel supply law W is obtained. fac / P3 and high pressure rotor conversion speed n' R Converted speed n to compressor inlet speed 2R25 The relationship between Get the high pressure rotor conversion speed n' R and the engine high pressure compressor rotor conversion speed n 2R The relationship f7(n 2R ); Calculate the speed n' according to the high pressure rotor R Converted speed n to the engine high pressure compressor rotor 2R The relationship between the engine starting fuel supply law W is obtained fac / P3 and core engine starting fuel supply law W f ' ac / P3 ' The relationship between Obtaining the fuel supply law for engine starting; The engine compressor inlet temperature T 25 Conversion speed n with low pressure rotor 1R The calculation method is: Convert the speed n according to the low-pressure rotor 1R The engine throttling characteristics are calculated every 5% step; based on the engine throttling characteristics calculation results, the engine compressor inlet temperature T is obtained. 25 Conversion speed n with low pressure rotor 1R Relationship, specifically: T 25 / T1=f2(n 1R ) Where T1 is the engine inlet temperature; after calculating the engine throttling characteristics, we get: The high pressure rotor conversion speed n' R Converted speed n to compressor inlet speed 2R25 The relationship is: Among them, T 25DesignPoint is the design point compressor inlet temperature; the engine starting fuel supply law is: <h2 style=";text-align:left;direction:ltr">W′<h2 style=";text-align:left;direction:ltr"> fac <h2 style=";text-align:left;direction:ltr"> / W′3=f6(n′<h2 style=";text-align:left;direction:ltr"> R <h2 style=";text-align:left;direction:ltr"> )==W<h2 style=";text-align:left;direction:ltr"> fac <h2 style=";text-align:left;direction:ltr"> / W3=f6(n<h2 style=";text-align:left;direction:ltr"> 2R25 <h2 style=";text-align:left;direction:ltr"> ); The high pressure rotor conversion speed n' R and the engine high pressure compressor rotor conversion speed n 2R The relationship is: Wherein, T1 is the engine inlet temperature; The engine starting fuel supply law W fac / P3 and core engine starting fuel supply law W f ' ac / P3 ' The corresponding relationship is: Wherein, T1 is the engine inlet temperature; the starting fuel supply rule of the engine is: When the engine is in the low speed state during starting: W fac / P3=f1(f7(n 2R )) When the engine is in the high speed state during starting: <h2 style=";text-align:left;direction:ltr">W<h2 style=";text-align:left;direction:ltr"> fac <h2 style=";text-align:left;direction:ltr"> / P3=f1(f7(n<h2 style=";text-align:left;direction:ltr"> 2R <h2 style=";text-align:left;direction:ltr"> ))×(f2(n<h2 style=";text-align:left;direction:ltr"> 1R <h2 style=";text-align:left;direction:ltr"> ))<h2 style=";text-align:left;direction:ltr"> 0.5 Where n is the physical speed of the high-pressure rotor of the engine, n′ is the physical speed of the high-pressure rotor of the core machine, P3 is the outlet pressure of the engine compressor, P′3 is the outlet pressure of the core machine compressor, and W fac is the fuel supply for engine starting, W′ fac is the starting fuel supply of the core engine; W3 is the outlet flow of the engine compressor, and W′3 is the outlet flow of the core engine compressor.

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