A method for designing a ground starting fueling for an aircraft gas turbine engine

Abstract

The application belongs to the field of aero-engine design and relates to a design method for ground starting and ignition fuel supply of an aero gas turbine engine. The method comprises the following steps: setting an atmospheric temperature low threshold and an atmospheric temperature high threshold, obtaining a current atmospheric temperature value in real time, calculating a difference between a high-pressure physical rotating speed of the engine and a converted rotating speed when it is judged that the current atmospheric temperature value is less than or equal to the atmospheric temperature low threshold or the current atmospheric temperature value is greater than or equal to the atmospheric temperature high threshold, and correcting an initial ignition fuel quantity according to the difference to form a new initial fuel quantity ignition formula; and gradually increasing the fuel supply quantity according to different ignition rates in different temperature intervals until the engine is successfully ignited when ignition is performed. The method can prevent initial ignition failure of the engine, quickly establish normal combustion conditions of a main combustion chamber of the engine, improve the success rate of ground starting of the engine, and is convenient to implement, has a short cycle and obvious effects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aero-engine design, and particularly relates to a ground starting ignition fuel supply design method for an aero-gas turbine engine. BACKGROUND

[0002] The primary condition for successful starting of an aero-engine is rapid and reliable ignition of the combustion chamber. The engine starting ignition characteristics are closely related to the combustion chamber characteristics, the core engine low speed characteristics and the engine ignition fuel supply law, and under the condition that the hardware technical state of any type of engine is determined, the optimized starting ignition fuel supply law can better realize the ignition of the combustion chamber, thereby improving the starting success rate of the engine. The current ignition fuel supply logic of the ground starting process of a certain type of engine is that, in order to avoid ignition stall, a soft ignition mode is adopted, the initial ignition fuel quantity under the same atmospheric pressure is a fixed value, as shown in formula 1, and after the fuel supply, the fuel quantity is gradually increased at a certain fuel supply increase rate until the ignition is successful to meet the condition of entering the closed loop for the rotation speed increase rate closed loop control.

[0003] W f =f(P H ) (1)

[0004] As can be seen from formula (1), the current initial ignition fuel quantity is mainly determined according to the atmospheric pressure, and under the same atmospheric pressure, the initial ignition fuel quantity is a fixed value. If the atmospheric temperature decreases, the engine conversion speed increases, and the intake flow increases, the same initial ignition fuel quantity is adopted, which causes lean ignition, and the low temperature fuel atomization effect is not good, which may cause the engine ground starting ignition failure. On the contrary, the atmospheric temperature rises, which causes rich ignition, and may also cause the engine ground starting ignition failure, and in the extreme case (a large amount of fuel is accumulated in the main combustion chamber or even the entire engine), the starting ignition explosion may occur.

[0005] Therefore, how to prevent the engine starting abnormality when the atmospheric temperature rises or decreases is a problem to be solved. SUMMARY

[0006] The purpose of the present application is to provide a ground starting ignition fuel supply design method for an aero-gas turbine engine, so as to solve the problem that the atmospheric temperature rise or decrease may cause the engine starting abnormality in the prior art.

[0007] The technical scheme of the present application is: a ground starting ignition fuel supply design method for an aero-gas turbine engine, comprising:

[0008] setting an atmospheric temperature low temperature threshold value and an atmospheric temperature high temperature threshold value, acquiring a current atmospheric temperature value in real time, and comparing the numerical value of the current atmospheric temperature value with the atmospheric temperature low temperature threshold value or the atmospheric temperature high temperature threshold value;

[0009] If the current atmospheric temperature is less than or equal to the low atmospheric temperature threshold or greater than or equal to the high atmospheric temperature threshold, then obtain the current engine high-pressure physical speed N. g and converted speed N r Calculate the engine's high-pressure physical speed N g and converted speed N r The difference between them is ΔN = N r -N g The initial ignition fuel quantity is then corrected based on the difference ΔN to form a new initial fuel quantity ignition formula.

[0010] When it is determined that the atmospheric temperature is less than or equal to the low atmospheric temperature threshold, the new initial fuel quantity ignition formula gradually increases the fuel supply at a first rate; when it is determined that the atmospheric temperature is greater than or equal to the high atmospheric temperature threshold, the new initial fuel quantity ignition formula gradually increases the fuel supply at a second rate; when it is determined that the atmospheric temperature is between the low atmospheric temperature threshold and the high atmospheric temperature threshold, the fuel supply is gradually increased at a third rate, and the first rate is greater than or equal to the third rate, and the third rate is greater than or equal to the second rate.

[0011] Determine if ignition was successful. If ignition was successful, the ignition and fuel supply process for starting the engine on the ground ends.

[0012] Preferably, the new initial fuel quantity ignition formula is:

[0013]

[0014] In the formula, A is a constant, and m and n are coefficients.

[0015] Preferably, the numerical range of the difference ΔN is: -4≤ΔN≤3.

[0016] Preferably, the specific method for gradually increasing the engine fuel supply is as follows: a first rate, a second rate, and a third rate are set respectively, and a rate increase time interval is set; three tables showing the change of ignition fuel quantity over time are set in the digital electronic controller, and each table sets several numerical nodes showing the change of engine ignition fuel quantity over time. When the engine is started and ignited on the ground, the corresponding rate is selected to gradually increase the ignition fuel supply according to different states, and the ignition fuel quantity is increased to the next numerical node when each rate increase time interval is reached, until ignition is successful.

[0017] The application discloses a ground starting and ignition fuel supply design method of an aero gas turbine engine. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions provided by the application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the application.

[0019] Figure 1 The figure is a schematic diagram of the whole process of the application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the application clearer, the following will combine the drawings in the embodiments of the application to make the technical solutions in the embodiments of the application more detailed.

[0021] A ground starting and ignition fuel supply design method of an aero gas turbine engine, as shown in Figure 1 includes the following steps:

[0022] Step S100, judging whether there is temperature abnormality

[0023] The atmospheric temperature low temperature threshold value and the atmospheric temperature high temperature threshold value are set, the current atmospheric temperature value is obtained in real time, and the numerical value of the current atmospheric temperature value is compared with the atmospheric temperature low temperature threshold value or the atmospheric temperature high temperature threshold value.

[0024] According to the original scheme, the standard day (T1=15℃, P1=101.3kPa) is determined, the high-pressure rotor physical rotation speed reaches N g Start fuel supply (fuel supply physical rotation speed), the ground starting initial ignition fuel quantity is A, the atmospheric pressure decreases, and the ground starting initial ignition fuel quantity also decreases, and details are shown in Table 1.

[0025] P H (kPa)]]> ≥101.3 90 80 70 60 ≤54.0 W f (kg / h) A A-10 A-20 A-30 A-40 A-45

[0026] In the embodiment, the atmospheric temperature low temperature threshold value is preferably set as 0℃, and the atmospheric temperature high temperature threshold value is preferably set as 30℃. Therefore, the temperature range between 0℃ and 30℃ is the normal working state of the engine.

[0027] Step S200: Perform initial oil quantity correction when the temperature is abnormal.

[0028] If the current atmospheric temperature is less than or equal to the low atmospheric temperature threshold or greater than or equal to the high atmospheric temperature threshold, then obtain the current engine high-pressure physical speed N. g and converted speed N r Calculate the engine's high-pressure physical speed N g and converted speed N r The difference between them is ΔN = N r -N g The initial ignition fuel quantity is then corrected based on the difference ΔN to form a new initial fuel quantity ignition formula.

[0029] Preferably, the new initial fuel quantity ignition formula is:

[0030]

[0031] In the formula, A is a constant, and m and n are coefficients.

[0032] 15℃ is the standard temperature under standard temperature. Generally, m is greater than n.

[0033] Preferably, the numerical range of the difference ΔN is: -4≤ΔN≤3.

[0034] High pressure physical speed N g and converted speed N r The value of ΔN changes continuously under different engine conditions, resulting in different values ​​under different conditions. For example, the ΔN under a typical condition point may be different from the ΔN under an atypical condition point. Therefore, when fuel is supplied after the engine starts on the ground, the values ​​of ΔN under different time points are recorded from front to back according to the time points, and a correction curve is formed. The correction curve is sent to the digital electronic controller, so that different correction amounts can be generated according to different time points.

[0035] This design ensures that the initial ignition fuel quantity is corrected under different atmospheric temperatures, preventing ignition failure.

[0036] Step S300: Gradually increase the fuel supply to the engine for ignition.

[0037] When it is judged that the atmospheric temperature is less than or equal to the atmospheric temperature low temperature threshold, i.e. T1≤0℃, the new initial oil quantity ignition formula gradually increases the fuel supply quantity at a first rate X% / s; when it is judged that the atmospheric temperature is greater than or equal to the atmospheric temperature high temperature threshold, i.e. T1≥30℃, the new initial oil quantity ignition formula gradually increases the fuel supply quantity at a second rate Y% / s; when it is judged that the atmospheric temperature is between the atmospheric temperature low temperature threshold and the atmospheric temperature high temperature threshold, the fuel supply quantity is gradually increased at a third rate Z%, and the first rate is greater than or equal to the third rate, and the third rate is greater than or equal to the second rate, i.e. X≥Z≥Y.

[0038] Preferably, the specific method for gradually increasing the engine fuel supply quantity is that: the first rate, the second rate and the third rate are set respectively, and a rate increasing time interval is set; three tables of ignition oil quantity changing with time are set in the digital electronic controller, and a plurality of numerical nodes of ignition oil quantity changing with time of the engine are set in each table; when the engine is started on the ground, the ignition fuel supply quantity is gradually increased according to the corresponding rate selected according to different states, and the ignition fuel supply quantity is increased to the next numerical node when each rate increasing time interval is reached, until the ignition is successful.

[0039] By gradually increasing the ignition fuel supply quantity at different rates under different atmospheric temperatures, the fuel supply quantity is increased at a faster speed when the temperature is lower, and the fuel supply quantity is increased at a slower speed when the temperature is higher, so that the ignition stability is ensured and the ignition success rate is further improved.

[0040] Step S400: the engine ground starting process ignition fuel supply is ended

[0041] It is judged whether the ignition is successful, if not, the fuel supply quantity is gradually increased according to step S300 until the ignition is successful, and if the ignition is successful, the engine ground starting process ignition fuel supply is ended.

[0042] The present application sets the atmospheric temperature low temperature threshold and the atmospheric temperature high temperature threshold, and obtains the current atmospheric temperature value in real time, when it is judged that the current atmospheric temperature value is less than or equal to the atmospheric temperature low temperature threshold or the current atmospheric temperature value is greater than or equal to the atmospheric temperature high temperature threshold, the difference between the engine high pressure physical rotating speed and the converted rotating speed is calculated, and the initial ignition oil quantity is corrected according to the difference to form a new initial oil quantity ignition formula; at the same time, the fuel supply quantity is gradually increased according to different ignition rates according to different temperature intervals when ignition, until the engine ignition is successful. The engine initial ignition failure can be prevented, and the engine main combustion chamber normal combustion condition can be quickly established, the engine ground starting success rate is improved, and the implementation is convenient, the cycle is short, and the effect is obvious.

[0043] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An aircraft gas turbine engine ground starting ignition fueling design method, characterized by, The application relates to an engine ground starting process ignition oil supply method. The method comprises the following steps: If the current atmospheric temperature value is less than or equal to the atmospheric temperature low temperature threshold or the atmospheric temperature value is greater than or equal to the atmospheric temperature high temperature threshold, the current engine high pressure physical rotation speed N is obtained g and the converted rotation speed N r , the difference ΔN between the engine high pressure physical rotation speed N g and the converted rotation speed N r is calculated, ΔN=N r -N g , and the initial ignition oil quantity is corrected according to the difference ΔN to form a new initial oil quantity ignition formula; Setting an atmospheric temperature low temperature threshold and an atmospheric temperature high temperature threshold, acquiring a current atmospheric temperature value in real time, and comparing the current atmospheric temperature value with the atmospheric temperature low temperature threshold or the atmospheric temperature high temperature threshold; When it is judged that the atmospheric temperature is less than or equal to the atmospheric temperature low temperature threshold, the new initial oil quantity ignition formula gradually increases the oil supply at a first rate; When it is judged that the atmospheric temperature is greater than or equal to the atmospheric temperature high temperature threshold, the new initial oil quantity ignition formula gradually increases the oil supply at a second rate; when it is judged that the atmospheric temperature is between the atmospheric temperature low temperature threshold and the atmospheric temperature high temperature threshold, the oil supply is gradually increased at a third rate, and the first rate is greater than or equal to the third rate, and the third rate is greater than or equal to the second rate; 2. The aircraft gas turbine engine ground start ignition fueling design method of claim 1, wherein, Judging whether ignition is successful, and if the ignition is successful, the engine ground starting process ignition oil supply stage is ended. The new initial oil quantity ignition formula is as follows:

3. The aircraft gas turbine engine ground start ignition fueling design method of claim 1, wherein: In the formula, A is a constant, and m and n are coefficients.

4. The aircraft gas turbine engine ground start ignition fueling design method of claim 1, wherein, The value range of the difference value Delta N is -4<=Delta N<=3. The specific method for gradually increasing the engine oil supply is as follows: first, second and third rates are set, and a rate increasing time interval is set; second, three tables of ignition oil quantity change with time are set in a digital electronic controller, and a plurality of ignition oil quantity value nodes of the engine change with time are set in each table; third, when the engine is started on the ground, corresponding rates are selected according to different states to gradually increase the ignition oil supply, and the ignition oil supply is increased to the next value node when each rate increasing time interval is reached, until ignition is successful.

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