Design method of ground crosswind starting fueling law for aero-engine

Abstract

The application belongs to the field of aero-engine starting oil supply, and is a design method for a ground backwind aero-engine starting oil supply law. Whether the current aero-engine is in a backwind state is first judged, if yes, whether the engine ignition is successful is judged again, if yes, the speed rise rate under the backwind state is corrected. The state of the ground starting ignition success or failure is judged in real time, so that when the engine is in the backwind state for ignition, if the starting fails, the starting is terminated in time, so that abnormal phenomena such as engine surge and deflagration caused by too much oil in the main combustion chamber are avoided, and engine structure damage is avoided. If it is judged that the engine ignition succeeds under the backwind condition, the engine starting acceleration oil supply flow is automatically corrected according to the backwind size, the surge margin in the engine starting process is ensured, and the starting success rate under the backwind environment is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engine starting fuel supply, and particularly relates to a design method of an aero-engine ground backwind starting fuel supply law. BACKGROUND

[0002] There are many and complex factors affecting the ground starting characteristics of an aero-gas turbine engine, and the wind environment is one of the important factors. The current ignition fuel supply design of the engine ground starting process does not consider the influence of the wind environment. The starting ignition logic of the engine is as follows: after the engine is pressed for a period of time, the engine starts to ignite (ignition needs to last for a period of time), and then when the speed or time reaches a certain specified value, the engine starts to supply fuel. After the fuel supply, the fuel supply amount is gradually increased at a certain fuel supply increase rate until the ignition succeeds to meet the condition of entering the closed loop for the speed rise rate closed loop control.

[0003] When the engine starts in the ground backwind environment, for example, Figure 1 wherein ① is the side wind, and ② is the backwind. When the backwind speed reaches a certain value, due to the wind pressure, the gas in the engine cannot flow normally, and even the phenomenon of reverse flow occurs, which may cause the main combustion chamber to fail to establish effective combustion conditions. Under the condition of continuous fuel supply, the fuel cannot be fully burned and is accumulated in the main combustion chamber or even the entire engine. In the extreme case, a large amount of accumulated fuel in the engine may be suddenly ignited by the main ignition device or the unburned flame existing in the main combustion chamber, and the phenomenon of deflagration may occur, which may cause damage to the structure of the engine. In addition, when the engine works in the backwind, the environmental wind direction is opposite to the engine airflow speed, which will hinder the outflow of the engine wake flow, increase the air flow back pressure, and reduce the engine surge margin. During the engine starting process, the airflow flow is small, and the core engine power is weak, so the influence of the backwind is more sensitive. When the wind force increases to a certain degree, the engine may stall and flame out.

[0004] Therefore, how to improve the starting success rate of the aero-engine under the backwind condition and prevent abnormal phenomena such as surge and deflagration is a problem to be solved. SUMMARY

[0005] The purpose of the present application is to provide a design method of an aero-engine ground backwind starting fuel supply law, so as to solve the problems of low starting success rate of the existing aero-engine under the backwind condition and easy occurrence of abnormal phenomena such as surge and deflagration.

[0006] The technical scheme of the present application is: a design method of an aero-engine ground backwind starting fuel supply law, comprising:

[0007] The external environment parameters and ignition fuel supply parameters of the aero-engine in a starting state are acquired, and it is determined whether the aero-engine is in a backside wind state, if yes, the starting process of the engine is monitored and the engine starting parameters are acquired;

[0008] It is determined whether the engine ignition is successful according to the starting parameters of the engine, if yes, the speed rise rate in the backside wind state is corrected according to the speed rise rate in the normal starting state without encountering the backside wind, if not, the engine is controlled to return to a parking state;

[0009] The method for judging the engine ignition failure is:

[0010] The starting start moment P H ≥75kPa, T6-T 6_供油初始时刻 ≤30℃ (the value can be adjusted in the range of 10-80℃), and lasts for 5 seconds;

[0011] The starting start moment P H ≤75kPa, T6-T 6_供油初始时刻 ≤30℃ (the value can be adjusted in the range of 10-80℃), and lasts for 5 seconds;

[0012] In the formula, T6 is the exhaust temperature after the low-pressure turbine, T 6_供油初始时刻 is the exhaust temperature at the initial moment of the low-pressure turbine fuel supply, P H is the engine cabin pressure, and when any of the above conditions is met, it is determined that the engine ignition fails.

[0013] Preferably, a "backside wind state" identifier and a "backside wind ignition failure state" identifier are respectively arranged in the aero-engine; when the "backside wind state" identifier is 1, the aero-engine is in the backside wind state and the control system records the highest value of the low-pressure physical speed within 15s after the starting button is pressed as n 1fz , when the "backside wind state" identifier is 0, the aero-engine is in the non-backside wind state and starts according to the original ignition fuel supply logic; when the "backside wind ignition failure state" identifier is 1, the aero-engine is in the backside wind ignition failure state, and when the "backside wind ignition failure state" identifier is not 1, i.e. 0, the aero-engine is in the backside wind ignition success state; after the ground starting is finished, the "backside wind ignition failure state" is set to 0.

[0014] Preferably, the formula for correcting the speed rise rate in the backside wind state is:

[0015]

[0016] In the formula, n 2dotbcfzt is the corrected speed rise rate in the backside wind state, n 2dot is the speed rise rate in the normal starting state without encountering the backside wind.

[0017] Preferably, P H Directly set P H = 80 kPa.

[0018] The application discloses a design method of an aero-engine ground backwind starting oil supply rule, which comprises the following steps: firstly judging whether the current aero-engine is in a backwind state, and if yes, secondly judging whether engine ignition is successful, and if yes, correcting the rotating speed rising rate in the backwind state; judging the state of the ground starting ignition success or failure in real time, so that when the engine is in the backwind state and ignition, if the starting fails, the starting is terminated in time, so that the abnormal phenomena such as engine surge and deflagration caused by too much oil in the main combustion chamber are avoided, and the engine structure damage is avoided; if the engine ignition in the backwind condition is successful, the engine starting acceleration oil supply flow is automatically corrected according to the backwind size, the surge margin in the engine starting process is ensured, and the starting success rate in the backwind environment is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] 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.

[0020] Figure 1 It is a schematic diagram of the backwind direction in the background art;

[0021] Figure 2 It is a schematic diagram of the whole process of the application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0023] A design method of an aero-engine ground backwind starting oil supply rule, as shown in Figure 2 The method comprises the following steps:

[0024] In step S100, the external environment parameters and the ignition oil supply parameters of the aero-engine in the starting state are acquired, and it is judged whether the current aero-engine is in a backwind state, specifically, the engine tail flow pressure, air flow back pressure and other parameters are used for judgment, if yes, the starting process of the engine is monitored and the engine starting parameters are acquired.

[0025] Preferably, a "backside wind state" identifier is set in the aero-engine; when the "backside wind state" identifier is 1, the aero-engine is in the backside wind state and the control system records the highest value of the low-pressure physical rotation speed within 15s after the starting button is pressed as n 1fz When the "backside wind state" identifier is 0, the aero-engine is in the non-backside wind state and starts according to the original ignition fuel supply logic.

[0026] In this way, the engine state can be directly obtained through the identifier data by observing the "backside wind state" identifier, which is relatively convenient.

[0027] In step S200, whether the engine ignition is successful is judged according to the starting parameters of the engine, which is judged through the starting time, engine temperature and rotation speed and the like, if successful, the rotation speed rising rate in the backside wind state is corrected according to the rotation speed rising rate in the normal starting state without encountering the backside wind; if not successful, the engine is controlled to return to the parking state.

[0028] The judgment method of the engine ignition failure is as follows:

[0029] Starting time P H ≥75kPa, T6-T 6_供油初始时刻 ≤30℃ (the value can be adjusted in the range of 10-80℃) and lasts for 5s;

[0030] Starting time P H ≤75kPa, T6-T 6_供油初始时刻 ≤30℃ (the value can be adjusted in the range of 10-80℃) and lasts for 5s;

[0031] In the formula, T6 is the exhaust temperature after the low-pressure turbine, T 6_供油初始时刻 is the exhaust temperature at the initial time of the low-pressure turbine fuel supply, P H is the engine cabin pressure, when any of the above conditions is met, the engine ignition failure can be determined. P H When the signal fails, P H =80kPa is directly set.

[0032] Preferably, a "backside wind ignition failure state" identifier is set in the aero-engine; when the "backside wind ignition failure state" identifier is established as 1, the aero-engine is in the backside wind ignition failure state, when the "backside wind ignition failure state" identifier is not established, it is 0, then the aero-engine is in the backside wind ignition success state; after the ground starting is finished, the "backside wind ignition failure state" is set to 0.

[0033] By judging the state of ground starting ignition success or failure in real time, when the engine is in the back wind state for ignition, if the starting fails, the starting is terminated in time, abnormal phenomena such as engine surge, deflagration and the like caused by too much oil accumulation in the main combustion chamber are ensured not to occur, and engine structure damage is avoided; if it is judged that the engine ignition succeeds under the back wind condition, the engine starting acceleration oil supply flow is automatically corrected according to the back wind size, the engine surge margin in the starting process is ensured, and the starting success rate under the back wind environment is improved.

[0034] Preferably, the formula for correcting the speed rising rate under the back wind state is:

[0035]

[0036] In the formula, n 2dotbcfzt is the speed rising rate under the back wind state, n 2dot is the speed rising rate under the normal starting without encountering the back wind. When encountering the back wind, the engine starting success rate is improved by reducing the speed rising rate.

[0037] Finally, it should be pointed out that: first, in the description of the present application, it should be pointed out that unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, which can be mechanical connection or electrical connection, or the communication between two elements, or direct connection, "up", "down", "left", "right" and the like are only used to indicate the relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may change;

[0038] Secondly: the present application discloses the structure involved in the embodiment of the present application, other structures can refer to the usual design, under the condition of no conflict, the same embodiment and different embodiments of the present application can be combined with each other;

[0039] Finally: the above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A design method for the fuel supply pattern of an aero-engine starting under ground-based back wind, characterized in that, The method comprises the following steps: acquiring external environment parameters and ignition fuel supply parameters of the aero-engine in a starting state, and judging whether the aero-engine is in a backside wind state, if yes, monitoring the starting process of the engine and acquiring engine starting parameters; judging whether the engine ignition is successful according to the engine starting parameters, if yes, correcting the speed rise rate in the backside wind state according to the speed rise rate in the normal starting state without encountering the backside wind, if not, controlling the engine to return to a parking state; the judging method of the engine ignition failure is: Condition 1: Start-up start time P H > 75 kPa, T6-T 6_供油初始时刻 ≤ 30°C for 5 seconds; Condition 2: Start-up start time P H ≤ 75 kPa, T6-T 6_供油初始时刻 ≤ 30°C for 5 seconds; In the formula, T6 is the exhaust temperature after the low-pressure turbine, and T... 6_供油初始时刻 P represents the exhaust temperature at the initial moment of low-pressure turbine oil supply. H Engine compartment pressure; if any of the above conditions are met, the engine ignition can be determined to have failed. The "backside wind state" mark and "backside wind ignition failure state" mark are arranged in the aero-engine respectively; when the "backside wind state" mark is 1, the aero-engine is in the backside wind state and the control system records the highest value of the low-pressure physical rotating speed within 15s after the starting button is pressed as n 1fz When the "backside wind state" mark is 0, the aero-engine is in the non-backside wind state and the starting is performed according to the original ignition fuel supply logic. the formula for correcting the speed rise rate in the backside wind state is: ； wherein the corrected rate of speed increase in the case of a backwind, the rate of speed increase in the case of a normal start without backwind.

2. The method of designing a ground crosswind starting fuel schedule for an aeroengine as recited in claim 1, wherein: when the "backside wind ignition failure state" identification is established as 1, the aero-engine is in the backside wind ignition failure state, and when the "backside wind ignition failure state" identification is not established, that is, 0, the aero-engine is in the backside wind ignition success state.

3. The method of designing a ground crosswind starting fuel schedule for an aeroengine as recited in claim 1, wherein: after the ground starting is finished, the "backside wind ignition failure state" is set as 0.

4. The method of designing a ground crosswind starting fuel schedule for an aeroengine as recited in claim 1, wherein: P H In case of signal failure, directly set P H =80kPa.

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