A method for judging surge during turbine engine start-up

Abstract

This disclosure provides a method for judging surge during the starting process of a turbocharged engine, including the following steps: when the engine speed is greater than a set speed, acquiring the change in the total intake air temperature over a certain period of time; if the change in the total intake air temperature is less than a specified value, it is determined that there is no surge during the engine starting process; if the change in the total intake air temperature is greater than a specified value, it is determined that there is surge during the engine starting process. Unlike conventional methods that judge surge by the rate of change of pressure pulsation after the compressor, this disclosure judges whether the engine is surging by sensing the change in the total intake air temperature during engine starting. It has the advantages of simple system composition and timely surge detection and resolution.

Description

Technical Field

[0001] This disclosure relates to the field of turbine engine technology, and in particular to a method for judging surge during the start-up process of a turbine engine. Background Technology

[0002] Small turbine engines used for missile launch are highly susceptible to surge during high-altitude, low-Mach windmill ignition and acceleration. This typically manifests as oscillations in the pressure signal after the compressor and an increase in the total intake air temperature. Furthermore, because the engine speed command is a converted speed, the actual converted speed decreases as the total intake air temperature rises, leading to a larger speed deviation. This causes the fuel supply regulator to increase the fuel supply, resulting in either fuel-rich engine shutdown or surge damage, ultimately causing mission failure.

[0003] Current conventional technology determines engine surge by observing the pulsation changes in the pressure signal after the compressor. This requires adding a pressure pulsation sensor after the compressor to the control system hardware and clearly identifying the mathematical model of engine surge in the software in order to develop the control program, which increases both hardware costs and the complexity of the control program.

[0004] Public content

[0005] The main objective of this disclosure is to provide a method for judging surge during the start-up process of a turbine engine, which aims to solve at least some of the aforementioned problems.

[0006] To achieve the above objectives, this disclosure provides a method for judging surge during the start-up process of a turbine engine, comprising the following steps:

[0007] When the engine speed is greater than the set speed, the change in the total intake air temperature of the engine over a certain period of time is obtained.

[0008] If the change in total intake air temperature is less than a specified value, it is determined that there is no surge during the engine start-up process;

[0009] If the change in total intake air temperature is greater than a specified value, it is determined that there is surge during engine start-up.

[0010] Optionally, before the step of obtaining the change in total intake air temperature over a certain period of time when the engine speed is greater than the set speed, the method further includes:

[0011] The engine's real-time speed is obtained, and timing begins when the engine's real-time speed is greater than the set speed;

[0012] The duration during which the real-time rotational speed is greater than the set rotational speed is collected;

[0013] If the duration exceeds two control cycles, the engine speed is determined to be greater than the set speed.

[0014] Optionally, when the engine speed is greater than a set speed, the step of obtaining the change in the total intake air temperature of the engine over a certain period of time includes:

[0015] Obtain the highest value of the engine intake air total temperature within a certain period of time;

[0016] Obtain the lowest value of the engine intake air total temperature within a certain period of time;

[0017] The difference between the highest value of the intake total temperature and the highest value of the intake total temperature is taken as the change in the intake total temperature.

[0018] Optionally, the method for judging surge during turbine engine startup further includes the following steps:

[0019] If it is determined that there is no surge during engine start-up, then adjust the fuel supply normally and accelerate to the set speed.

[0020] If it is determined that there is surging during engine start-up, reduce the fuel supply within a specified time, then adjust the fuel supply normally and accelerate to the set speed.

[0021] Optionally, the steps for reducing fuel consumption within a specified time period include the following:

[0022] Within N control cycles, the fuel supply in each control cycle is reduced by 2L / h compared to the fuel supply in the previous control cycle.

[0023] After N reductions in fuel quantity, maintain the fuel supply constant for M control cycles, and then adjust the fuel supply normally.

[0024] The turbocharged engine start-up surge detection method disclosed herein determines whether the engine is surging by sensing changes in the total intake air temperature during engine start-up. It has the advantages of simple system composition and timely surge detection and resolution. Furthermore, it includes the following beneficial effects: it adds anti-surge fault-tolerant functions to the control software without increasing the hardware resources of the control system; it broadens the engine ignition and start-up envelope. Without this function, the engine frequently surges and stalls during start-up in low-temperature environments of (6km, 0.5Ma) and -45℃. Adding this function completely solves the engine's low-temperature start-up problem at (6km, 0.5Ma) and -45℃, and also enables normal start-up in low-temperature environments of (7km, 0.5Ma) and -45℃. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 A schematic flowchart of an embodiment of the turbine engine start-up surge judgment method provided in this disclosure;

[0027] Figure 2 for Figure 1 The flowchart of the surge judgment method for the turbine engine start-up process provided in the document is shown.

[0028] The realization of the purpose, functional features and advantages of this disclosure will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0030] It should be noted that if the embodiments of this disclosure involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0031] Furthermore, if the embodiments of this disclosure involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this disclosure.

[0032] In the field of aero-engines, the operating conditions are extremely harsh, often involving high temperatures, high pressures, and high-speed rotation. Therefore, to improve the performance, reliability, and service life of aero-engines, it is essential to fully understand their operating conditions. Surge is one of the most common operating conditions. If surge occurs during aero-engine operation and is not diagnosed and eliminated in a timely manner, it can lead to engine shutdown, component damage, and in severe cases, even engine failure. Current conventional technology judges engine surge by detecting changes in the pressure signal pulsation after the compressor. This requires adding a pressure pulsation sensor after the compressor to the control system hardware and clearly identifying the mathematical model of engine surge in the software before the control program can be written, increasing hardware costs and control program complexity. Therefore, this disclosure determines engine surge by sensing changes in the total intake air temperature during engine startup. Based on existing engine control system technology, it does not add new hardware resources, has a simple system composition, and has been experimentally verified to be effective.

[0033] See Figure 1 The engine's real-time speed is collected by a magnetoelectric speed sensor installed on the engine. When the real-time engine speed is greater than 65% of the engine's closed-loop speed, this moment is taken as the timing start point or timing zero point, and the change in the total intake air temperature at the engine inlet is calculated over a certain period of time. If the change in the total intake air temperature is greater than a specified value, it is considered that surge has occurred during the engine start-up process; otherwise, surge has not occurred. The specific specified value is obtained through statistical analysis of engine high-altitude test and flight test data.

[0034] See Figure 2 In this embodiment, to eliminate sudden changes caused by signal interference, the time for determining that the engine speed is greater than the set speed cannot be too short, nor too long, generally within 2-3 control cycles. A control cycle is the time it takes for the engine control software to complete one calculation output; in this embodiment, it is 10ms. Specifically, the real-time engine speed is acquired, and timing begins when the real-time engine speed exceeds the set speed; the duration for which the real-time engine speed is greater than the set speed is collected; when the duration exceeds two control cycles, the engine speed is determined to be greater than the set speed.

[0035] In this embodiment, to obtain the change in the engine's total intake temperature, the highest and lowest values ​​of the total intake temperature within a certain time period are obtained, and the change in total intake temperature is obtained by subtracting the lowest value from the highest value. It should be noted that in this embodiment, the highest and lowest values ​​of the total intake temperature within a certain time period specifically refer to the highest and lowest values ​​within 4 seconds. Statistical analysis of high-altitude ignition acceleration tests and flight tests of this type of turbine engine shows that the time from engine ignition speed entering the closed loop to surge-rich fuel-rich shutdown is generally within 8 to 10 seconds. Therefore, based on the statistical results of engine test data, a time of 4 seconds was specified. Furthermore, in this embodiment, the specified change value for the total intake temperature refers to 4°C; that is, if the change exceeds 4°C, surge is determined to occur during engine startup; otherwise, it is not. Based on statistical data from engine flight tests and high-altitude test ignition and acceleration tests, the increase in intake air temperature within 4 seconds after engine surge is 6–8°C. Statistical analysis of normal engine start-up and flight test data from the high-altitude test, considering the change in total intake air temperature caused by the missile's descent within 4 seconds, shows a change in total intake air temperature of 1–2°C within 4 seconds. Therefore, based on the statistical results from the high-altitude test and flight tests, taking a total intake air temperature change of 4°C within 4 seconds will not cause a false surge assessment, nor will it cause an undetected surge assessment.

[0036] Furthermore, if no surge occurs during engine startup, the fuel supply is regulated normally, and the engine accelerates to the set speed. If surge occurs during engine startup, the fuel supply is rapidly reduced within a limited time, and then normal regulation and acceleration to the set speed are resumed. In this embodiment, the fuel supply is reduced by 40 L / h within 200 ms, maintained for 300 ms, and then normal regulation is resumed. The control system's operation cycle is 10 ms. In this embodiment, one control cycle reduces the fuel supply by 2 L / h, for 20 cycles, then the fuel supply is maintained constant for 30 cycles before normal regulation is resumed.

[0037] In summary, the beneficial effects of this invention include: without increasing the hardware resources of the control system, it adds anti-surge fault-tolerant functionality to the control software; it broadens the engine ignition and starting envelope, as the engine frequently surges and stalls when starting in low-temperature environments of (6km, 0.5Ma) and -45℃ without this function, while adding this function completely solves the engine starting problem in low-temperature environments of (6km, 0.5Ma) and -45℃, and also enables normal starting in low-temperature environments of (7km, 0.5Ma) and -45℃. Furthermore, high-altitude bench tests were conducted to verify the false surge detection; that is, the fuel reduction function was intentionally triggered during normal engine starting, and the test results showed that the engine accelerated normally, reaching the set state.

[0038] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method for judging surge during the start-up process of a turbine engine, characterized in that, Includes the following steps: Step S10: When the engine speed is greater than the set speed, obtain the change in the total intake air temperature of the engine over a certain period of time; Step S20: If the change in total intake air temperature is less than a specified value, it is determined that there is no surge during the engine start-up process; Step S30: If the change in total intake air temperature is greater than a specified value, it is determined that there is surge during the engine start-up process; The steps preceding step S10 also include: Step S01: Obtain the real-time speed of the engine, and start timing when the real-time speed of the engine is greater than the set speed; Step S02: Collect the duration during which the real-time rotational speed is greater than the set rotational speed; Step S03: When the duration is more than two control cycles, it is determined that the engine speed is greater than the set speed.

2. The method for judging surge during turbine engine start-up as described in claim 1, characterized in that, When the engine speed is greater than the set speed, the steps for obtaining the change in the total intake air temperature of the engine over a certain period of time include: Step S101: Obtain the highest value of the engine intake air total temperature within a certain period of time; Step S102: Obtain the lowest value of the engine intake air total temperature within a certain period of time; Step S103: The difference between the highest value and the lowest value of the total intake temperature is taken as the change in the total intake temperature.

3. The method for judging surge during turbine engine start-up as described in claim 1, characterized in that, The method for judging surge during turbine engine startup also includes the following steps: Step S40: If it is determined that there is no surge during the engine starting process, adjust the fuel supply normally and accelerate to the set speed. Step S50: If it is determined that there is surging during the engine start-up process, reduce the fuel supply within a specified time, then adjust the fuel supply normally and accelerate to the set speed.

4. The method for judging surge during turbine engine start-up as described in claim 3, characterized in that, The steps for reducing fuel consumption within a specified time include the following: Step S501: Within N control cycles, the fuel supply in each control cycle is reduced by 2L / h compared to the fuel supply in the previous control cycle. Step S502: After reducing fuel N times, maintain the fuel supply unchanged for M control cycles, and then adjust the fuel supply normally.

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