A design method for aero-engine start-up speed change rate correction

Abstract

The application belongs to the field of aero-engine design and is a design method for a starting speed change rate correction of an aero-engine. A starting machine working speed change rate and a starting machine disengaging speed change rate correction amount are set. When the starting machine works, the speed change rate controlled by a control system is executed according to the speed change rate reference of the starting machine working state, and a first speed change rate n dot控制1 is obtained in this state. When the starting machine disengages, a starting machine disengaging speed change rate correction amount n dot修正 is obtained, the speed change rate controlled by the control system is corrected by the starting machine disengaging speed change rate correction amount n dot修正 to the first speed change rate, and a second speed change rate n dot控制2 is obtained. By associating the starting speed change rate with the starting machine disengaging, the starting machine speed change rate is corrected when the starting machine disengages, effectively solving the problem of engine starting surge caused by the starting machine disengaging time being earlier than the disengaging speed.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engine design, and particularly relates to a design method for a starting speed change rate correction of an aero-engine. BACKGROUND

[0002] The process of accelerating the engine from a static state to a slow-speed working state is called the ground starting process of the engine. As an indispensable link of engine operation, its performance is directly related to the use characteristics of the engine.

[0003] The ground starting process of the aero-engine is generally divided into the following three stages.

[0004] Stage I: The engine rotor is accelerated to the ignition fuel supply speed n by the starter. In this stage, the output power of the starter overcomes the resistance torque of the engine and drives the engine rotor to accelerate.

[0005] Stage II: When the engine reaches the ignition fuel supply speed n, the fuel is supplied to the combustion chamber and ignited, and the turbine starts to generate power and drive the engine together with the starter to accelerate until the starter is disconnected at the disconnection speed n.

[0006] Stage III: From the moment the engine reaches the disconnection speed n, the engine is accelerated to the stable slow-speed speed by the remaining power of the turbine, and the starting process ends.

[0007] According to the working principle of the engine starting process, the aero-engine starting technology design mainly includes the selection of the combustion ignition state, the determination of the ability and working range of the auxiliary power, the design of the combustion chamber fuel supply law, the design of the engine geometric adjustable area control law, etc. Among them, the design of the combustion chamber fuel supply law is particularly important. The commonly used starting fuel supply law mainly includes:

[0008] 1) Calculate the fuel supply amount W according to the starting time, W f =f(t) control law;

[0009] 2) Calculate the fuel supply amount W according to the combustion chamber pressure, W f =f(P3) control law;

[0010] 3) Calculate the fuel supply amount W according to the combustion chamber oil-gas ratio, W f / P3=f(n) control law;

[0011] 4) Calculate the fuel supply amount W according to the speed change rate, W f =f(n dot ) control law.

[0012] The rotational speed change rate is used to calculate the oil supply during the starting process, which is a common control scheme for the starting of an aero-engine. The application is a rotational speed change rate correction method after the starter is disengaged, based on the rotational speed change rate for calculating the oil supply.

[0013] When the engine starts, the starter drives the rotor component of the engine to rotate, and when the oil supply rotational speed (n 供油 ) is reached, the oil supply to the combustion chamber is started, and the rotor component is driven by the engine turbine and the starter, and when the starter rotational speed (n 脱开 ) or the disengagement time (t 脱开 ) is reached (generally designed to reach the rotational speed first), the starter is disengaged from the engine rotor, and the rotor is driven by the engine turbine to the idle speed. The oil supply is controlled according to the predetermined rotational speed change rate during the starting process.

[0014] The rotational speed change rate is related to the engine rotational speed. After the starter is disengaged, the rotational speed change rate of the engine rotor decreases suddenly due to the sudden decrease in external power input. Therefore, when the rotational speed change rate is determined, the rotational speed change rate corresponding to the disengagement rotational speed changes suddenly, as shown in Figure 1 .

[0015] In actual use, due to individual differences of the engine, atmospheric environment and other factors, there may be a situation where the disengagement rotational speed is not reached when the disengagement time is reached, and at this time the rotational speed change rate is still relatively large. Due to the lack of external power input from the starter, if the current rotational speed change rate is to be reached, the fuel supply to the combustion chamber needs to be increased, which is likely to cause engine starting surge. SUMMARY

[0016] The application provides a design method for correcting the rotational speed change rate during the starting of an aero-engine, to solve the problem of large rotational speed change rate and difficult control during the starting of an aero-engine in the prior art.

[0017] The technical scheme of the application is a design method for correcting the rotational speed change rate during the starting of an aero-engine, comprising:

[0018] The rotational speed change rate during the operation of the starter and the rotational speed change rate correction amount after the starter is disengaged are set; during the operation of the starter, the rotational speed change rate controlled by the control system is executed according to the rotational speed change rate reference during the operation of the starter, and a first rotational speed change rate n dot控制1 is obtained under this state;

[0019] When the starter is disengaged, the rotational speed change rate correction amount n dot修正 after the starter is disengaged is obtained, and the control system controls the rotational speed change rate by correcting the first rotational speed change rate by the rotational speed change rate correction amount n dot修正 after the starter is disengaged, to obtain a second rotational speed change rate n dot控制2 .

[0020] Preferably, the starter disengagement post-rotation speed change rate correction amount is:

[0021]

[0022] In the formula, M CT is the starter output power, M K is the compressor consumption power, η m is the mechanical efficiency, and J Z is the rotor rotational inertia moment.

[0023] Preferably, the first rotation speed change rate n dot控制1 is:

[0024] n dot控制1 = n dot基准 = f1(n)

[0025] In the formula, n dot基准 is the rotation speed change rate when the starter is working.

[0026] Preferably, the second rotation speed change rate n dot控制2 is:

[0027] n dot控制 = n dot基准 -n dot修正 = f1(n)-f2(n).

[0028] Preferably, the rotation speed change rate n dot基准 when the starter is working is obtained by collecting the rotation speed when the starter is working or existing starter working data.

[0029] Preferably, the starter disengagement post-rotation speed change rate correction amount n dot修正 gradually decreases over time.

[0030] The design method for the aero-engine starting rotation speed change rate correction of the application sets the rotation speed change rate when the starter is working and the starter disengagement post-rotation speed change rate correction amount; when the starter is working, the rotation speed change rate controlled by the control system is executed according to the rotation speed change rate reference of the starter working time, and the first rotation speed change rate n dot控制1 in this state is obtained; when the starter is disengaged, the starter disengagement post-rotation speed change rate correction amount n dot修正 is obtained, the control system controls the rotation speed change rate to correct the first rotation speed change rate by the starter disengagement post-rotation speed change rate correction amount n dot修正 , and the second rotation speed change rate n dot控制2 is obtained. By associating the starting rotation speed change rate with the starter disengagement, the starter rotation speed change rate is corrected when the starter is disengaged, effectively solving the problem of engine starting surge caused by the starter disengagement time being earlier than the disengagement rotation speed. Attached Figure Description

[0031] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0032] Figure 1 This is a schematic diagram of the speed change rate during the starting process in the background art.

[0033] Figure 2 This is a schematic diagram of the overall process of this application;

[0034] Figure 3 This is a schematic diagram of the total speed change rate during the starting process of this application. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] A design method for correcting the rate of change of starting speed of aero-engines, such as Figure 2 As shown, it includes the following steps:

[0037] Step S100: Set the speed change rate when the starter is working and the speed change rate correction amount after the starter is disengaged; when the starter is working, the speed change rate controlled by the control system is executed according to the speed change rate benchmark when the starter is working, and the first speed change rate n in this state is obtained. dot控制1 According to the first speed change rate n dot控制1 Calculate the starter oil supply under the current conditions.

[0038] The first speed change rate n dot控制1 for:

[0039] n dot控制1 =n dot基准 =f1(n) (1)

[0040] In the formula, n dot基准 The rate of change of starter speed during operation is obtained by collecting starter speed data or using existing starter operating data.

[0041] Step S200, in the starting process, when reaching the disengagement time or disengagement speed, the control system sends a starter disengagement instruction, and at the same time, the starting speed change rate is corrected, and the fuel supply amount control is performed according to the corrected speed change rate in the subsequent starting process. Specifically, when the starter is disengaged, the starter disengagement after speed change rate correction amount n dot修正 , the control system controls the speed change rate through the starter disengagement after speed change rate correction amount n dot修正 The first speed change rate is corrected to obtain the second speed change rate n dot控制2 .

[0042] Wherein, the starter disengagement after speed change rate correction amount n dot修正 is:

[0043] n dot修正 =f2(n) (2)

[0044] The second speed change rate n dot控制2 is:

[0045] n dot控制 =n dot基准 -n dot修正 =f1(n)-f2(n) (3)

[0046] The starter disengagement after speed change rate correction amount n dot修正 As shown in Figure 3 , wherein the solid line is the first speed change rate n dot控制1 ; the dotted line is the second speed change rate n dot控制2 . It can be seen that it gradually decreases with time, thereby being able to reduce the problem of step change of the speed change rate corresponding to the disengagement speed.

[0047] The symbols used in the present application are as follows:

[0048] Symbol table

[0049]

[0050] The present application sets the speed change rate when the starter works and the starter disengagement after speed change rate correction amount; when the starter works, the speed change rate controlled by the control system is executed according to the speed change rate reference when the starter works, and the first speed change rate n dot控制1 in this state is obtained; when the starter is disengaged, the starter disengagement after speed change rate correction amount n dot修正 is obtained, and the control system controls the speed change rate through the starter disengagement after speed change rate correction amount n dot修正 The first speed change rate is corrected to obtain the second speed change rate n dot控制2By associating the starting speed change rate with the starter disengagement, the starter speed change rate is corrected when the starter disengages, effectively solving the problem of engine starting surge caused by the starter disengaging time being earlier than the disengaging speed.

[0051] Finally, it should be noted that the present application discloses an embodiment of the drawings, only involves the structure involved in the present application, other structures can refer to the usual design, in the case of no conflict, the same embodiment and different embodiments of the present application can be combined with each other;

[0052] Finally: the above only for the preferred embodiments of the present application, and not for limiting the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. A design method for turbofan engine start rate of rotation variation correction, characterized in that, Comprising: setting a change rate of rotational speed when the starter is operating and a correction amount of change rate of rotational speed after the starter is disengaged; In the starter operation, the control system controls the rate of change of the rotation speed in accordance with the rate of change of the rotation speed reference in the starter operation, and acquires the first rate of change of the rotation speed n dot控制1 ; At the time of starter disengagement, the starter disengagement after rotation speed change rate correction amount n is acquired dot修正 The control system controls the rotation speed change rate through the starter disengagement after rotation speed change rate correction amount n dot修正 The first rotation speed change rate is corrected to obtain the second rotation speed change rate n dot控制2 ; the correction amount of change rate of rotational speed after the starter is disengaged is: ； ； where M CT is the starter output power, M K is the compressor consumption power, η m is the mechanical efficiency, J Z is the rotor moment of inertia; The first rotational speed change rate n dot控制1 is: ； wherein n dot基准 is the rate of change of rotational speed when the starter is operating; The second rotational speed change rate n dot控制2 is: ； The correction amount n for the rate of change of speed after the starter is disengaged dot修正 It gradually decreases over time.

2. The design method for a change rate of start-up rotational speed of an aero-engine according to claim 1, characterized in that: The rate of change of the rotational speed n of the starter when it is in operation dot基准 The rate of change of the rotational speed n of the starter when it is in operation

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