A correction method for the speed rise rate of aircraft engine ground start

Abstract

The present application relates to the field of aircraft engine design and is a method for correcting the ground start speed rate of an aircraft engine. The method comprises setting a speed rate correction term and a temperature correction term, and then setting an engine start temperature threshold. If the atmospheric temperature at engine start is less than or greater than the engine start temperature threshold, the method controls the engine according to different curves, resulting in a first correction curve and a second correction curve. The first correction curve and the second correction curve are written into a digital electronic controller. The digital electronic controller receives current engine start data in real time, reads the corresponding engine start temperature information, and, based on the temperature information, retrieves the corresponding data of the first correction curve or the second correction curve to correct the ground start speed rate of the engine, thereby controlling the fuel supply pattern. This method can avoid abnormal phenomena such as overheating and surge during the start process, thereby improving engine starting performance and start success rate.

Description

Technical Field

[0001] The present application relates to the field of aircraft engine design, and in particular to a method for correcting the ground starting speed increase rate of an aircraft engine. Background Art

[0002] The ground starting fuel supply law of a certain type of engine adopts a design method based on closed-loop control of the speed increase rate. When designing the speed increase rate control law, the starting time requirements, starter output torque, turbine torque, engine resistance torque, accessory load, moment of inertia and other conditions are comprehensively considered. The design results are corrected by the results of ground and air starting tests to obtain the speed increase rate under sea level and standard atmospheric conditions. In actual use, the design law is corrected as necessary considering non-standard conditions such as atmospheric pressure (P1) and atmospheric temperature (T1). As a given requirement of the engine control system, the specific correction formula is:

[0003]

[0004] N in the formula doths is the speed increase rate directly calculated by the control system, N dot is the corrected speed increase rate.

[0005] As can be seen from Formula 1, the current method for correcting the speed rise rate is mainly to perform atmospheric temperature and pressure corrections. If the influence of atmospheric pressure is not considered (when the atmospheric pressure is the same), as the atmospheric temperature decreases, the speed rise rate gradually increases and the starting time is shortened.

[0006] According to GJB 241A-2010 "General Specifications for Aviation Turbojet and Turbofan Engines" Section 3.7.9.2 "Starting Requirements", "In the absence of ram pressure, the total time for starting from sea level to an altitude of 4.35 km should be Figure 1 It can be seen that there is a certain temperature point where the engine starting time is the shortest. Based on this point, the engine starting time is extended regardless of whether the atmospheric temperature increases or decreases, rather than shortening as the temperature decreases.

[0007] In addition, according to actual test results and reference to relevant literature, under low temperature conditions, the engine starting time is significantly prolonged. This is because as the temperature decreases, the viscosity of the lubricating oil increases, resulting in poor lubrication of the rotor bearings and a gradual increase in the starting resistance torque, which in turn causes insufficient starter power, rotor jamming, longer rotation time, and extended starting time.

[0008] Under low temperature conditions, if the existing correction method is used, the speed increase rate will increase, causing the engine to exceed the stable operating range during starting, resulting in abnormal phenomena such as overheating and surge, thereby affecting the engine starting performance and starting success rate.

[0009] Therefore, how to prevent the engine from exceeding the stable operating range during the starting process under low temperature conditions is a problem that needs to be solved. Summary of the Invention

[0010] The purpose of this application is to provide a method for correcting the speed increase rate of an aircraft engine during ground starting, so as to solve the problem in the prior art that the engine easily exceeds the stable operating range during the starting process.

[0011] The technical solution of the present application is: a method for correcting the rate of increase of the ground starting speed of an aircraft engine, comprising:

[0012] Set the engine starting temperature judgment threshold;

[0013] Set the speed rise rate correction term k1, and the engine ground start speed rise rate correction formula is:

[0014]

[0015] Setting the temperature correction term k2, the above formula can be written as:

[0016]

[0017] When the atmospheric temperature is lower than the set temperature threshold, a first correction curve is set for the speed increase rate correction term k1 and the temperature correction term k2 to change with temperature; when the atmospheric temperature is greater than or equal to the normal temperature threshold, a second correction curve is set for the speed increase rate correction term k1 and the temperature correction term k2 to change with temperature;

[0018] The first correction curve and the second correction curve are written into a digital electronic controller. The digital electronic controller receives the current engine starting data in real time, reads the corresponding engine starting temperature T1 information, and calls out the corresponding data of the first correction curve or the second correction curve according to the temperature change to correct the engine ground starting speed increase rate, thereby controlling the fuel supply pattern.

[0019] Preferably, the speed increase rate correction term and the temperature correction term are combined to form a parameter k. The digital electronic controller controls the engine ground start fuel supply rule according to the parameter k, and the speed increase rate is obtained as follows:

[0020] When the engine starting temperature T1 does not reach the normal engine starting temperature threshold, the value of the parameter k increases linearly with the temperature; when the engine starting temperature exceeds the normal engine starting temperature threshold, the value of the parameter k decreases linearly with the temperature.

[0021] Preferably, the adjustment range of the parameter k is 0.5-2.

[0022] Preferably, the method for the digital electronic controller to call the first correction curve and the second correction curve is: setting a table showing the changes of the first correction curve and the second correction curve with temperature, and setting a number of numerical nodes of the engine starting temperature T1 and the parameter k in the table; when an engine starting temperature T1 is obtained, if the engine starting temperature T1 corresponds to a numerical node in the table, directly obtaining the corresponding parameter k to control the engine ground starting fuel supply law; if the engine starting temperature T1 is between two adjacent numerical nodes, interpolating and calculating the k value, and then using the k value to correct the engine ground starting speed increase rate.

[0023] Preferably, the specific values ​​of the speed rise rate correction term k1 and the temperature correction term k2 that change with the engine starting temperature are obtained by collecting data related to the speed rise rate change under current low temperature conditions and data related to the standard speed rise rate change, and calculating the corresponding differences.

[0024] The present invention discloses a method for correcting the speed rise rate during ground starting of an aircraft engine. The method includes setting a speed rise rate correction term and a temperature correction term, and then setting a normal engine start temperature threshold. When the speed rise rate correction term and the temperature correction term are less than or greater than the normal engine start temperature threshold, control is performed according to different curves, respectively, to obtain a first correction curve and a second correction curve. The first correction curve and the second correction curve are written into a digital electronic controller. The digital electronic controller receives current engine start data in real time, reads corresponding engine start temperature information, and, based on the temperature change, retrieves the corresponding data of the first correction curve or the second correction curve to control the engine ground start fuel supply pattern. Under low temperature conditions, the corrected (given) speed rise rate is reduced, and the actual engine start fuel supply is relatively reduced, thereby avoiding abnormal phenomena such as overheating and surge during the start process, thereby improving engine starting performance and start success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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.

[0026] Figure 1 A graph showing the relationship between the engine ground starting time (stationary, no ramjet, sea level to 4.35 km) and the ambient air temperature in the background art;

[0027] Figure 2 This is a schematic diagram of the overall process of this application. DETAILED DESCRIPTION

[0028] 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.

[0029] A method for correcting the speed increase rate of an aircraft engine during ground start-up, such as Figure 2 As shown, the following steps are included:

[0030] Step S100, set correction items

[0031] The engine starting temperature judgment threshold is set. In this embodiment, the judgment threshold is set to 15°C. The speed rise rate correction term k1 is set. The speed rise rate is calculated based on the speed rise rate correction term k1 to achieve T1 < 15°C. As the temperature decreases, the speed rise rate gradually decreases and the starting time is extended. For details, see formula (2); when T1 ≥ 15°C, the speed rise rate correction result is the same as formula (1):

[0032]

[0033] Set the temperature correction term k2, and calculate the speed increase rate based on the temperature correction term k2 as formula (3):

[0034]

[0035] The specific values ​​of the speed rise rate correction term k1 and the temperature correction term k2 that change with the engine starting temperature are obtained by collecting the speed rise rate change-related data under the current low temperature conditions and the standard speed rise rate change-related data, and calculating the corresponding differences to ensure the accuracy of the speed rise rate correction and temperature correction.

[0036] Step S200: Establishing a correction curve

[0037] When the atmospheric temperature is lower than the set temperature threshold, a first correction curve is set for the speed increase rate correction term k1 and the temperature correction term k2 to change with temperature; when the atmospheric temperature is higher than or equal to the set temperature threshold, a second correction curve is set for the speed increase rate correction term k1 and the temperature correction term k2 to change with temperature;

[0038] Preferably, the speed increase rate correction term k1 and the temperature correction term k2 are combined to form a parameter k. The digital electronic controller controls the engine ground start fuel supply law according to the parameter k, and the speed increase rate is obtained as formula (4):

[0039]

[0040] When the engine starting temperature does not reach the engine starting temperature threshold, parameter k increases linearly with temperature, representing the first correction curve. When the engine starting temperature exceeds the engine starting temperature threshold, parameter k decreases linearly with temperature, representing the second correction curve. The adjustment range of parameter k is 0.5 to 2.

[0041] In one example, the engine starting temperature judgment threshold is set to 15°, and the change of parameter k with the engine starting temperature is shown in Table 1:

[0042] Table 1 k value under various temperature conditions

[0043] <![CDATA[T1(K)]]> k <![CDATA[T1(K)]]> k <![CDATA[T1(K)]]> k 213 0.9206 268 0.9875 308 0.9670 223 0.9300 273 0.9925 313 0.9593 233 0.9406 278 0.9963 323 0.9443 243 0.9525 283 0.9900 333 0.9300 248 0.9594 288 1 353 0.9032 253 0.9663 293 0.9914 373 0.8787 258 0.9738 298 0.9831 - - 263 0.9813 303 0.9749 - -

[0044] By combining the speed rise rate correction term k1 and the temperature correction term k2, the amount of calculation required for the ground start fuel supply rule of the engine is reduced, and subsequent storage and retrieval are facilitated.

[0045] The obtained first correction curve and second correction curve are both linear curves, which can more conveniently and efficiently control the fuel supply law of the engine ground start.

[0046] Step S300: Control the engine ground start fuel supply rule according to the correction curve

[0047] The first correction curve and the second correction curve are written into a digital electronic controller. The digital electronic controller receives the current engine starting data in real time, reads the corresponding engine starting temperature T1 information, and calls out the first correction curve or the second correction curve according to the temperature information to correct the engine ground starting speed increase rate, thereby controlling the fuel supply pattern.

[0048] Preferably, the method for the digital electronic controller to call the first correction curve and the second correction curve is: setting a table showing the changes of the first correction curve and the second correction curve with temperature, and setting a number of numerical nodes of the engine starting temperature T1 and the parameter k in the table; when an engine starting temperature T1 is obtained, if the engine starting temperature T1 corresponds to a numerical node in the table, directly obtaining the corresponding parameter k to control the engine ground starting fuel supply law; if the engine starting temperature T1 is between two adjacent numerical nodes, interpolating and calculating the k value, and then using the k value to correct the engine ground starting speed increase rate.

[0049] This application sets an engine speed rise rate correction term, a temperature correction term, and a starting temperature judgment threshold. If the atmospheric temperature at the time of engine start is less than or greater than the engine temperature judgment threshold, control is performed according to different curves, respectively, to obtain a first correction curve and a second correction curve. The first correction curve and the second correction curve are written into a digital electronic controller. The digital electronic controller receives current engine start data in real time, reads the corresponding engine start temperature information, and calls out the corresponding data of the first correction curve or the second correction curve based on the temperature information to correct the engine ground start speed rise rate, thereby controlling the fuel supply pattern. Under low temperature conditions, the corrected (given) speed rise rate is reduced, and the actual engine starting fuel supply is relatively reduced, which can avoid abnormal phenomena such as overheating and surge during the start process, thereby improving the engine starting performance and start success rate.

[0050] Using this method, the engine's given speed rise rate is reduced under low-temperature conditions (T1 < 15°C). Evaluation and verification show that the maximum exhaust temperature during engine starting drops by approximately 30°C, and the start time is extended by approximately 2 to 4 seconds, both meeting engine starting performance requirements. Under high-temperature conditions (T1 ≥ 15°C), engine starting performance remains unchanged.

[0051] 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 correcting the rate of increase of the ground starting speed of an aircraft engine, characterized in that: include: Set the engine starting temperature judgment threshold; Set the speed rise rate correction term k1, and the engine ground start speed rise rate correction formula is: Setting the temperature correction term k2, the above formula can be written as: When the atmospheric temperature is lower than the set temperature threshold, a first correction curve is set for the speed increase rate correction term k1 and the temperature correction term k2 to change with temperature; When the atmospheric temperature is greater than or equal to the normal temperature threshold, a second correction curve is set for the speed increase rate correction term k1 and the temperature correction term k2 to change with temperature; The first correction curve and the second correction curve are written into a digital electronic controller. The digital electronic controller receives the current engine starting data in real time, reads the corresponding atmospheric temperature T1 information when the engine is started, and calls out the corresponding data of the first correction curve or the second correction curve according to the temperature change to correct the engine ground starting speed increase rate, thereby controlling the fuel supply pattern.

2. The method for correcting the aircraft engine ground start speed increase rate according to claim 1, wherein: The speed rise rate correction term k1 and the temperature correction term k2 are combined to form a parameter k. The digital electronic controller corrects the engine ground start speed rise rate according to the parameter k. The speed rise rate correction formula is: When the engine starting temperature T1 does not reach the engine starting set temperature threshold, the value of the parameter k increases linearly with the temperature; when the engine starting temperature exceeds the engine starting normal temperature threshold, the value of the parameter k decreases linearly with the temperature.

3. The method for correcting the aircraft engine ground start speed increase rate according to claim 2, wherein: The adjustment range of the parameter k is 0.5-2.

4. The method for correcting the aircraft engine ground start speed increase rate according to claim 2, wherein: The method for the digital electronic controller to call the first correction curve and the second correction curve is as follows: a table is set to show the changes of the first correction curve and the second correction curve with temperature, and a plurality of numerical nodes of the engine starting temperature T1 and the parameter k are set in the table; when an engine starting temperature T1 is obtained, if the engine starting temperature T1 corresponds to a numerical node in the table, the corresponding parameter k is directly obtained to correct the engine ground starting speed increase rate; if the engine starting temperature T1 is between two adjacent numerical nodes, the k value is interpolated and calculated, and then the k value is used to correct the engine ground starting speed increase rate.

5. The method for correcting the aircraft engine ground start speed increase rate according to claim 1, wherein: The specific values ​​of the speed increase rate correction term k1 and the temperature correction term k2 that change with the engine starting temperature are obtained by collecting data related to the speed increase rate change under current low temperature conditions and data related to the standard speed increase rate change, and calculating the corresponding differences.

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